Дисертації з теми "Photocatalytic membranes"

Photocatalytic membranes have been designed using two types of fine-scale alumina fibres, namely Nano Alumina Fibre (NAF) from Metallurg Engineering, Estonia and commercially available Saffil® Alumina Fibre (SAF) produced by Saffil Limited, UK. NAF fibres have an average diameter of about 15 nm and SAF about 4 μm. Membranes were produced in various ways. The fibre network architecture within the membranes, along with their porosity, specific surface area and mechanical properties, have been examined. These NAF-SAF membranes were impregnated with titania-based sol-gel coatings, to produce photocatalytic membranes. Their mechanical properties, specific surface area and flow properties were assessed and photocatalytic potential was measured by studying rates of degradation of aqueous dye solution. Membranes with photo-active top layers were designed by sedimentation of a fibrous layer of NAF-SAF, containing titania nanoparticles on a pre-sedimented support layer. Two types of photocatalyst were used, one a commercially available anatase nanopowder and the other silver-coated anatase. The latter was produced via modification of the first. Optimisation of the nanoparticle loadings was performed via assessing their photocatalytic efficiency. Specific permeability values were obtained experimentally and by prediction from the pore architecture. A novel form of photo-active membrane was designed by direct casting of milled SAF and titania-based sol-gel into circular moulds. Effects of fibre milling time and fibre to sol-gel ratio on their performance were studied, besides mechanical properties, porosity and specific surface area. Their flow properties and photocatalytic efficiency were also examined. Due to the availability of these fibres, especially the high production rates (kg/h range) and low cost of NAF, these membranes offer potential for large scale application.

De nos jours, les produits chimiques toxiques industriels ne sont pas toujours traités proprement, et leurs contaminants peuvent directement affecter la sécurité de l'eau potable. La photocatalyse, «une technologie verte» est une approche efficace et économique qui joue un rôle important dans la conversion de l'énergie solaire et la dégradation des polluants organiques. Ce manuscrit de thèse rapporte sur le développement des matériaux avancés (basés sur TiO2 et ZnO) susceptibles d'exploiter l'énergie solaire renouvelable pour résoudre les problèmes de pollution environnementale. Une partie de ce travail a été consacrée pour l’amélioration de l’activité photocatalytique du TiO2 sous lumière UV et visible. Par conséquent, les nanofibres composites de rGO/TiO2, BN/TiO2 et BN-Ag/TiO2 ont été élaborées en utilisant la technique d'électrofilage (electrospinning). La deuxième partie porte sur le ZnO, ainsi que les nanotubes multi co-centriques de ZnO/ZnAl2O4 et les nanotubes de ZnO dopés Al2O3 qui ont été synthétisés en combinant les deux techniques : dépôt de couche atomique (ALD) et electrospinning. Les propriétés morphologiques, structurelles et optiques de toutes les nanostructures synthétisées ont été étudiées par différentes techniques de caractérisations. Les résultats ont montré que les propriétés chimiques et physiques ont un effet très important sur les propriétés photocatalytiques des matériaux synthétisés. En outre, il a été constaté que l'effet de dopage conduit à une séparation de charge efficace dans le photocatalyseur, ce qui rend l’activité photocatalytique plus efficace. De plus, le méthyle orange et le bleu de méthylène ont été utilisés comme modèle de référence. Une amélioration significative et une stabilité à long terme de l’activité photocatalytique ont été observées avec les matériaux dopés comparés aux matériaux non-dopés sous lumière UV et visible. Des tests antibactériens contre Escherichia coli ont été également effectués; les résultats indiquent que BN-Ag/TiO2 présente à la fois des propriétés photocatalytiques intéressantes pour la dégradation des composés organiques et pour l'élimination des bactéries
Nowadays, industrial toxic chemicals are still not properly treated and these contaminants may directly impact the safety of drinking water. Photocatalysis “a green technology” is an effective and economical approach and plays an important role in solar energy conversion and degradation of organic pollutants. This thesis manuscript reports on developing advanced materials (based on TiO2 and ZnO) being capable of exploiting renewable solar energy for solving the environmental pollution problems. A part of this work was dedicated to improve the UV and visible light TiO2 photoresponse. Therefore, rGO/TiO2, BN/TiO2 and BN-Ag/TiO2 composties nanofibers were successfully elaborated using the electrospinning technique. The second part focused on ZnO. Novel structures of ZnO/ZnAl2O4 multi co-centric nanotubes and Al2O3 doped ZnO nanotubes were designed by combining the two techniques of atomic layer deposition (ALD) and electrospinning. The morphological, structural and optical properties of all synthesized nanostructures were investigated by several characterization techniques. The results show that the chemical and physical properties have a high impact on the photocatalytic properties of the synthesized materials. Moreover, it was found that the doping effect lead to a more efficient charge separation in the photocatalyst, which is an advantage for photocatalytic activities. In addition, methyl orange and methylene blue were used as model reference. A significant enhancement and a long-term stability in the photocatalytic activity were observed with the doped materials compared to the non-doped ones under both UV and visible light. Antibacterial tests against Escherichia coli have also been performed; the results indicate that BN-Ag/TiO2 present interesting photocatalytic properties for both organic compound degradation and bacterial removal

Thesis (MScEng)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: The purpose of this study was to develop modi ed tract-etched membranes using nanocomposite TiO2 for advanced water treatment processes. Photocatalytic oxidation and reduction reactions take place on TiO2 surfaces under UV light irradiation, therefore sunlight and even normal indoor lighting could be utilised to achieve this effect. In membrane ltration, caking is a major problem, by enhancing the anti-fouling properties of photocatalysts to mineralise organic compounds the membrane life and e ciency can be improved upon. In this study the rst approach in nanocomposite membrane development was to directly modify the surface of polyethylenetherephthalate (PET) track-etched membranes (TMs) with titanium dioxide (TiO2) using inverted cylindrical magnetron sputtering (ICMS) for TiO2 thin lm deposition. The second approach was rst to thermally evaporate silver (Ag) over the entire TM surface, followed by sputtering TiO2 over the silver-coated TM. As a result a noble metal-titania nanocomposite thin lm layer is produced on top of the TM surface with both self-cleaning and superhydrophilic properties. Reactive inverted cylindrical magnetron sputtering is a physical vapour deposition method, where material is separated from a target using high energy ions and then re-assimilated on a substrate to grow thin lms. Argon gas is introduced simultaneously into the deposition chamber along with O2 (the reactive gas) to form TiO2. The photocatalytic activity and other lm properties, such as crystallinity can be in uenced by changing the sputtering power, chamber pressure, target-to-substrate distance, substrate temperature, sputtering gas composition and ow rate. These characteristics make sputtering the perfect tool for the preparation of di erent kinds of TiO2 lms and nanostructures for photocatalysis. In this work, the utilisation of ICMS to prepare photocatalytic TiO2 thin lms deposited on track-etched membranes was studied in detail with emphasis on bandgap reduction and TM surface regeneration. Nanostructured TiO2 photocatalysts were prepared through template directed deposition on track-etched membrane substrates by exploiting the good qualities of ICMS. The TiO2-TM as well as Ag-TiO2-TM thin lms were thoroughly characterised. ICMS prepared TiO2 lms were shown to exhibit good photocatalytic activities. However, the nanocomposite Ag-TiO2 thin lms were identi ed to be a much better choice than TiO2 thin lms on their own. Finally a clear enhancement in the photocatalytic activity was achieved by forming the Ag-TiO2 nanocomposite TMs. This was evident from the band-gap improvement from 3.05 eV of the TiO2 thin lms to the 2.76 eV of the Ag-TiO2 thin lms as well as the superior surface regenerative properties of the Ag-TiO2-TMs.
AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om verbeterde baan-ge etste membrane (BMe) met behulp van nano-saamgestelde titaandioksied (TiO2) vir gevorderde water behandeling prosesse te ontwikkel. Fotokatalitiese oksidasie- en reduksie reaksies vind plaas op die TiO2 oppervlaktes onder UV-lig bestraling, en dus kan sonlig en selfs gewone binnenshuise beligting gebruik word om die gewenste uitwerking te verkry. In membraan ltrasie is die aanpaksel van onsuiwerhede 'n groot probleem, maar die verbetering van die self-reinigende eienskappe van fotokatalisators deur organiese verbindings te mineraliseer, kan die membraan se leeftyd en doeltre endheid verbeter word. In hierdie studie was die eerste benadering om nano-saamgestelde membraan ontwikkeling direk te verander deur die oppervlak van polyethylenetherephthalate (PET) BMe met 'n dun lagie TiO2 te bedek, met behulp van reaktiewe omgekeerde silindriese magnetron verstuiwing (OSMV).Die tweede benadering was eers om silwer (Ag) termies te verdamp oor die hele BM oppervlak, gevolg deur TiO2 verstuiwing bo-oor die silwer bedekte BM. As gevolg hiervan is 'n edelmetaal-titanium nano-saamgestelde dun lm laag gevorm bo-op die oppervlak van die BM, met beide self-reinigende en verhoogde hidro liese eienskappe. OSMV is 'n siese damp neerslag metode, waar materiaal van 'n teiken, met behulp van ho e-energie-ione, geskei word, en dan weer opgeneem word op 'n substraat om dun lms te vorm. Argon gas word gelyktydig in die neerslag kamer, saam met O2 (die reaktiewe gas), vrygestel om TiO2 te vorm. Die fotokatalitiese aktiwiteit en ander lm eienskappe, soos kristalliniteit, kan be nvloed word deur die verandering van byvoorbeeld die verstuiwingskrag, die druk in die reaksiekamer, teiken-tot-substraat afstand, substraattemperatuur, verstuiwing gassamestelling en vloeitempo. Hierdie eienskappe maak verstuiwing die ideale hulpmiddel vir die voorbereiding van die verskillende soorte TiO2 lms en nanostrukture vir fotokatalisasie. In hierdie tesis word OSMV gebruik ter voorbereiding van fotokatalitiese TiO2 dun lms, wat gedeponeer is op BMe. Hierdie lms word dan in diepte bestudeer, met die klem op bandgaping vermindering en BM oppervlak hergenerasie. Nanogestruktureerde TiO2 fotokataliste is voorberei deur middel van sjabloongerigte neerslag op BM substrate deur die ontginning van die goeie eienskappe van OSMV. Die TiO2-BM dun lms, sowel as Ag-TiO2-BM dun lms, is deeglik gekarakteriseer. OSMV voorbereide TiO2 dun lms toon goeie fotokatalitiese aktiwiteite. Nano-saamgestelde Ag-TiO2 dun lms is egter ge denti seer as 'n veel beter keuse as TiO2 dun lms. Ten slotte is 'n duidelike verbetering in die fotokatalitiese aktiwiteit bereik deur die vorming van die Ag-TiO2 nano-saamgestelde BMe. Dit was duidelik uit die bandgapingverbetering van 3,05 eV van TiO2 dun lms in vergelyking met die 2,76 eV van Ag-TiO2 dun lms. 'n Duidelike verbetering is behaal in die fotokatalitiese aktiwiteit deur die vorming van die Ag-TiO2 nano-saamgestelde TMs.

Le dépôt chimique en phase vapeur assisté par plasma est appliqué pour préparer des couches minces amorphes de TiO2 à basse température. Un recuit à 300 °C pendant un temps minimum de 4,5 h permet de former la phase cristalline anatase. Les principales caractéristiques de ces couches minces comme leur structure cristalline, leur microstructure, leur largeur de bande interdite et leur hydrophilie de surface, sont déterminées. Leurs performances fonctionnelles comme photocatalyseurs sont d'abord examinées selon le test breveté par Pilkington, consistant à éliminer sous irradiation UV de l'acide stéarique préalablement adsorbé sur les couches de TiO2 ici déposées sur des plaquettes de silicium. Des membranes M100 (couche continue de TiO2) et M800 (couche de TiO2 couvrant les grains de support) sont préparées sur les couches de surface macroporeuses de supports poreux en alumine, de tailles moyennes de pores respectives, 100 nm et 800 nm. Ces membranes sont testées en condition "statique", avec la diffusion d'un soluté organique dilué dans l'eau. Pour le bleu de méthylène, on montre que la quantité de composé détruit par unité de surface de membrane et par unité de temps est égale à 2 × 10-8 mol m-2 s-1 pour la membrane M100 et 1 × 10-8 mol m-2 s- 1 pour la membrane M800. Ces membranes sont également testées dans des conditions "dynamiques", à savoir en procédé baromembranaire, avec deux configurations différentes (couche photocatalytique du côté de l'alimentation ou du côté du perméat) et trois composés organiques différents (bleu de méthylène, acide orange 7 et phénol). La modélisation du procédé (adsorption et réaction photocatalytique) est finalement réalisée à partir des données expérimentales disponibles
Plasma-enhanced chemical vapor deposition is applied to prepare amorphous TiO2 thin films at low temperature. Post-annealing at 300 °C for minimal staying time 4.5 h is required to form crystalline anatase phase. Characteristics of the TiO2 thin films including crystalline structure, microstructure, band gap and surface hydrophilicity, are determined. Functional performance of these anatase thin films as photocatalysts is first examined with patented Pilkington assessment by removing, under UV irradiation, stearic acid initially adsorbed on TiO2 layers here deposited on silicon wafers. Membranes M100 (TiO2 continuous layer) and M800 (TiO2-skin on support grain) are prepared on the macroporous top layer of porous alumina supports with an average pore size of 100 nm and 800 nm, respectively. These membranes are tested in “static” condition under the effect of diffusion of an organic solute in water. For Methylene Blue it is shown that the quantity of destroyed compound per unit of membrane surface area and per unit of time is equal to 2×10−8 mol m-2 s-1 for M100 and 1×10−8 mol m-2 s-1 for M800. These membranes are also tested in “dynamic” conditions, i.e. pressure-driven membrane processes, with two different configurations (photocatalytic layer on the feed side or on the permeate side) and three different organics (Methylene Blue, Acid Orange 7 and phenol). Process modelling (adsorption and photocatalysis reaction) is finally carried out from the available experimental outputs

Cette thèse porte sur l’élaboration et l’étude des performances de membranes d’ultrafiltration PVDF-TiO2 possédant des propriétés anti-colmatantes et photo-induites. La membrane est obtenue par application de la méthode de séparation de phases induite par un non-solvant sur un collodion de polyfuorure de vinylidène au sein duquel ont été incorporées des nanoparticules de TiO2. Il est montré : i) que la presence des nanoparticules de TiO2 les propriétés membranaires, et notamment le flux de perméat, par rapport à la membrane PVDF ; ii) que l’augmentation de la température de préparation de la membrane permettait de modifier la structure membranaire, en passant d’une morphologie constituée principalement de macrovides (dite en “doigts de gants”) à des températures basses à une morphologie spongieuse, contenant des pores de plus petite taille, à température élevée. Au-delà de la structure membranaire, des propriétés telles que la perméabilité, la porosité, la résistance mécanique, la cristallinité et les propriétés thermiques sont également influences par les changements de température de formation. Lorsque les membranes PVDF-TiO2 sont mises en oeuvre en mode photo-filtration (c.-à-d. filtration avec irradiation ultraviolette (UV) continue sur la membrane), le flux à l’eau pure de la membrane PVDF-TiO2 est encore augmenté, du fait du phénomène d’hydrophilicité photo-induite des nanoparticules de TiO2. Des premières estimations suggèrent que la photo-filtration par les membranes PVDF-TiO2 serait une économiquement rentable, car le gain en termes de filtration et qualité d’eau l’emporterait sur le cout énergétique induit par l’irradiation UV. En outre, l’efficacité de la photo-filtration a été évaluée avec des solutions d’alimentation synthétiques contenant des composés inorganiques et organiques représentatifs des eaux de surface. Il a été montré que si la plupart des ions inorganiques communément rencontrés dans l’eau potable n’ont aucun effet sur l’efficacité de la photo-filtration, la coexistence de Cu2+ et HCO3- dans l’eau d’alimentation entraîne un colmatage inorganique sévère qui inhibe le phénomène hydrophilicité photoinduite. En outre, la membrane PVDF-TiO2 présente également des flux plus élevés et une activité photocatalytique lors de la photo-filtration de solutions contenant des matières colmatantes organiques comme les acides humiques ou l’alginate de sodium. En conclusion, la membrane composite PVDF-TiO2 a démontré des propriétés et des performances significativement améliorées par rapport à la membrane PVDF, a fortioti lorsqu’elle est mise en oeuvre dans un système de photo-filtration sous irradiation UV. Ainsi, ce sont des matériaux prometteurs pour des applications membranaires en traitement de l’eau
This thesis deals with the elaboration and performance of a specific type of ultrafiltration membrane with anti-fouling and photo-induced properties, the PVDF-TiO2 composite membrane. The membrane was fabricated via the nonsolvent-induced phase separation method by incorporating titanium dioxide (TiO2) nanoparticles into the polyvinylidene fluoride (PVDF) polymer matrix. The TiO2 nanoparticles played a significant role in facilitating the membrane formation process and improving the composite membrane properties compared to the neat PVDF membrane. It was demonstrated that, by changing the membrane preparation temperature, the membrane structure could be affected dramatically, notably the morphological dominance of finger-like macrovoids at lower temperatures and their diminution in both size and number when temperature increased. Other membrane properties also saw systematic transitions with changes in formation temperature, as characterized by permeability, porosity, mechanical strength, crystallinity, and thermal properties. In terms of performance, the PVDF-TiO2 membrane exhibited superior permeate flux compared to the neat PVDF membrane. More importantly, when being operated in photo-filtration mode (i.e. filtration with continuous ultraviolet (UV) irradiation on the membrane), the pure water flux of PVDF-TiO2 membrane could be further increased, thanks to the enhanced hydrophilicity of the membrane, which comes from the photo-induced hydrophilicity phenomenon of TiO2. Preliminary estimations suggest that photo-filtration is a cost-effective method, as the benefit from enhanced water output outweighs the extra energy demand for UV irradiation. Furthermore, the efficiency of photo-filtration was evaluated with synthetic feed solutions containing inorganic and organic contents representative in surface water. It was identified that, while most of the common inorganic ions in drinking water had no effects on photo-filtration efficiency, the coexistence of Cu2+ and HCO3- in the feed led to severe inorganic fouling and inhibited the photo-induced hydrophilicity phenomenon. Besides, the PVDF-TiO2 membrane also showed its stronger flux performance and photocatalytic activity during photo-filtration of solutions containing organic foulants like humic acids or sodium alginate. In conclusion, the PVDF-TiO2 composite membrane exhibited much improved properties and performance compared to the neat PVDF membrane, and even stronger performance when operated in photo-filtration mode. Thus, it is a promising candidate to be used in membrane-based applications for water treatment

The thesis constitutes an investigation into the production of floating photocatalytic particles (FPP) as a low cost, low carbon footprint and chemical-free wastewater treatment. It is anticipated that this approach would be particularly attractive for developing countries where it could reduce incidences of disease and pollution. The particles were manufactured from cocoa butter (CB), and contained either photocatalytic nanoparticle titanium dioxide TiO2 (P25) or silver-doped TiO2 (0.5% w/w). The photocatalytic activity of the particles was evaluated by means of the decolourisation of the dye indigo carmine (IC). Three arrangements were used; small scale treatment using Petri dishes, an 1800 ml batch-recirculation photoreactor and an 8 litre UV contactor. Membrane emulsification (ME) was the technique used here to generate particles of controlled size. The particles were in effect what are known as Pickering emulsions in which the solid fat core (CB) was stabilised by TiO2 nanoparticles, resulting in composite particles that float easily and can receive incident light to generate highly reactive free radical species. The FPPs were characterised by FEGSEM and EDs mapping analysis, and the images obtained displayed a spherical structure with a rough outer surface, and the EDs showed a good coverage of TiO2 on the surface of at a maximum loading of 10% w/w. Tests were conducted to assess the stability of the particles when used in repeated cycles. Reuse of the particles caused a significant drop of photodegradation activity after four cycles to 42% of that of freshly prepared particles. The correlation of photocatalytic activity with silver dosage was also investigated. The highest photocatalytic activity was achieved at 0.5 wt. % of silver doped TiO2 and was some 10% greater than for un- doped particles. The organic carbon release resulted from TOC analysis for the FPPs that were exposed to UV light for 8.5 hr in water was less than 1 wt. %. First order reaction kinetics were exhibited during decolourisation of IC dye with respect to the initial dye concentration, radiation intensity, percentage coverage of the liquid surface by the FPPs, and the catalytic loading. For a static system (i.e. no forced convection), the most effective surface coverage was identified as being in the range of 60 to 80%. A linear source spherical emission model (LSSE) was adopted to estimate the intensity of the incident radiation on the surface of the FPP layer in the photoreactor and validated. In addition, a preliminary kinetic model to describe of the effect of the photocatalytic active surface concentration of TiO2 as well as the efficient intensity flux in the kinetic model was developed for the FPP layer photoreactor.

La dépollution de l'eau est un des enjeux majeurs du XXIème siècle. Si différentes techniques de retraitement existent déjà, nous investiguons une nouvelle méthode associant les propriétés des membranes filtrantes à celles des matériaux photocatalytiques. Ainsi, nous avons étudié la croissance et l'activité photocatalytique de structures de type noyau/coquille de ZnO/SnO2 intégrées dans des membranes méso-poreuses (alumine poreuse) et macro-poreuses (fibres de verre). L'activité photocatalytique de ces matériaux a été évaluée sur des polluants modèles tels que le bleu de méthylène ou l'acide salicylique, mais aussi sur des polluants organiques identifiés dans les eaux de la rivière luxembourgeoise Alzette. L'impact environnemental des matériaux développés a été déterminé grâce a des analyses de cytotoxicité sur des cellules colorectales de type Caco-2, ainsi que sur des bactéries marines de type Vibrio Fischeri
Water treatment is one of the main challenge to overcome on the XXIst century. If many different techniques already exist, we investigate a new process associating the properties of porous membranes and photocatalytic materials. Thus, we studied the growth and photoactivity of core/shell structures of ZnO/SnO2 integrated into mesoporous (AAO) and macro-porous (glass fiber) membranes . The photocatalytic activity of these materials has been evaluated on organic pollutants like methylene blue or salicylic acid, but also on molecules found in the Luxembourgish Alzette river. The environmental impact of the synthesized structures has been determined with cytotoxic analyses on Caco-2 cells and Vibrio Fischeri bacteria

Perfluorosulfonate ionomers, such as Nafion® have been shown to demonstrate a profound affinity for large cationic complexes, and the study of polymer-bound cations may provide insight regarding Nafion® morphology by contrasting molecular size with existing models. The trimetallic complex, [{(bpy)2Ru(dpp)}2RhBr2] 5+, is readily absorbed by ion exchange into Na+ -form Nafion® membranes under ambient conditions. The dimensions of three different isomers of the trimetallic complex are estimated to be: 23.6 Å × 13.3 Å × 10.8 Å, 18.9 Å × 18.0 Å × 13.7 Å, and 23.1 Å × 12.0 Å × 11.4 Å, yielding an average molecular volume of 1.2×103 Å3 . At equilibrium, the partition coefficient for the ion-exchange of the trimetallic complex into Nafion® from a DMF solution is 5.7 × 103 . Furthermore, the total cationic charge of the exchanged trimetallic complexes counterbalances 86 ± 2% of the anionic SO3 − sites in Nafion®. The characteristic dimensions of morphological models for the ionic domains in Nafion® are comparable to the molecular dimensions of the large mixedmetal complexes. Surprisingly, SAXS analysis indicates that the complexes absorb into the ionic domains of Nafion® without significantly changing the ionomer morphology. Given the profound affinity for absorption of these large cationic molecules, a more open-channel model for the morphology of perfluorosulfonate ionomers is more reasonable, in agreement with recent experimental findings. In contrast to smaller monometallic complexes, the time- v dependent uptake of the large trimetallic cations is biexponential. This behavior is attributed to a fast initial ion-exchange process on the surface of the membrane, accompanied by a slower, transport-limited ion-exchange for sites in the interior of the ionomer matrix. The development of Nafion®/[{(bpy)2Ru(dpp)}2RhBr2] 5+ modified electrodes is also described for both FTO electrodes and materials made from electrospun carbon mats. The [{(bpy)2Ru(dpp)}2RhBr2] 5+ complexes behave as photocatalytic hydrogen production catalysts in the Nafion® membrane. Furthermore, a second bulk photoelectrolysis experiment with the Nafion®/[{(bpy)2Ru(dpp)}2RhBr2] 5+/FTO electrodes shows an enhancement of catalytic activity compared to the first photoelectrolysis experiment. This enhancement is attributed to halide loss following the first reduction process. Lastly, electrospun carbon nanofiber mats behave as electron donor materials for [{(bpy)2Ru(dpp)}2RhBr2] 5+/Nafion® membranes.
Ph. D.

Le traitement des rejets textiles se fait habituellement via une filière physico-chimique couplée à un traitement biologique. La qualité de l’effluent obtenu obéit difficilement aux normes de recyclage ou de rejet dans le milieu naturel. Dans cet objectif, différentes combinaisons sont proposées: la coagulation floculation (CF) et/ou l’adsorption sur charbon actif (CAP) en poudre couplée aux techniques membranaires (microfiltration (MF) ou ultrafiltration (UF)), la photocatalyse couplée à un traitement aérobie biologique (système membranaire (BRM) ou réacteur discontinu séquentiel (RDS)) ou au traitement anaérobie par voie biologique ou chimique. Une comparaison générale a été réalisée pour optimiser le traitement adéquat. La combinaison CF-CAP-UF est un traitement efficace pour la réduction de la DCO, de la couleur et de la turbidité. La dégradation de deux colorants textiles (azoïque et phthalocyanine) a été étudiée par photocatalyse simple ou combinée à un BRM. Le traitement photocatalytique a été réalisé en présence de dioxyde de titane fixé sur un support en fibres de cellulose dans un réacteur à film tombant en présence d’irradiation UV. Pour les deux types de réacteurs biologiques, bien que la biomasse ait été influencée par la variation de la concentration en colorant et par le mode de fonctionnement continu pour le BRM, elle a pu résister. Après le pré-traitement nous avons obtenu une complète décoloration mais les sous produits photocatalytiques demeurent toxiques et peuvent empêcher l’abattement de la DCO. Dans une dernière partie, nous avons testé le couplage de la photocatalyse à un traitement chimique par hydrogénation catalytique ou biologique par boues granulaires. Cette dernière possibilité s’avère être efficace puisque des taux de décoloration supérieurs à 90% ont été atteints pour différents types de colorants et qu’aucune toxicité des produits obtenus lors du pré-traitement photocatalytique n’a été détectée
The treatment of textile wastewater is usually done by a set of physicochemical processes coupled with a biological treatment. The effluent quality abides with difficulty the norms for reuse or discharge in environment. Various treatment combinations have been tested such as coagulation-flocculation (CF) and adsorption on activated carbon (PAC) coupled with membrane technologies (microfiltration (MF) or ultrafiltration (UF)), photocatalysis coupled with a biological treatment (membrane bioreactor (MBR) or a sequential batch reactor (SBR) or a biological and chemical anaerobic treatment. A general comparison was made to optimise the appropriate treatment. The combination CF-PAC-UF is the most effective of non-biological systems in terms of COD, absorbance and turbidity removal. The degradation of an azoïc and a phthalocyanine textile dyes by simple photocatalysis or combined to a membrane bioreactor has been investigated. Photocatalysis was achieved in a falling film reactor containing titanium dioxide fixed on cellulose fibres under UV irradiation. For both biological systems, although biomass was influenced by the variation of dyes concentration and the continuous operating mode for the MBR, it could resist to the applied conditions. However, even after pre-treatment where full decolouration was achieved, photocatalytic by-products were toxic and could inhibit COD removal. Chemical and biological anaerobic treatment have been applied to textile dyes and combined with a photocatalytic process. Photocatalysis was able to remove more than 90% color from crude as well as autoxidized reduced dye solutions. The photocatalytic end-products were not toxic toward methanogenic bacteria

Ce travail de thèse est consacré à l'élaboration de membrane photocatalytique à partir de nanoparticules de TiO2 obtenues par voie sol-gel (système TTIP-eau). Les sols sont préparés dans un réacteur à micro-mélange rapide (turbulent). L'effet de l'hydrodynamique au sein de différents mélangeurs (T simple, T chicanes, T rétrécissement) sur la morphologie et l'activité photocatalytique de nanoparticules déposées sur des plaques d'α-alumine a été étudié. Les dépôts de TiO2 ont été réalisés durant la période d'induction de la réaction sol-gel. Le mélange des réactifs a été simulé en utilisant un logiciel de modélisation numérique (modèle k-ε), Les différences hydrodynamiques au sein du micro-mélange a seulement un impact significatif sur le temps de stabilité des nanoparticules (période d'induction). Des couches minces et des membranes photo-actives ont été réalisées en vue du couplage membrane et réaction photocatalytique. Ces membranes ont été caractérisées et testées en photocatalyse. Elles ont montrées de bonnes photo-activités. Des tests de couplage direct séparation/photodégradation ont été réalisés sur des solutions aqueuses d'acide orange 7. Ce dispositif expérimental a permis de mettre en évidence une augmentation de flux de perméation significative avec de l'eau et en présence de colorant en solution. L'effet de la concentration et du pH de la solution a été évalué sur les flux de perméat et sur la photodégradation
This PhD work is devoted to the elaboration of photocatalytic membranes using TiO2 nanoparticles synthetized by sol-gel process (titanium tetra-isopropoxyde precursor – water). Sols are prepared in sol-gel reactor with rapid turbulent micro-mixing. The effect of hydrodynamic using 3 T mixers (T simple, T with 3 baffles and T with narrow) during the mixing was studied with k-ε modeling Computational fluid Dynamics (CFD), as well as the morphology and the photo-activity of thin layers deposited on alumina support during induction period. Differences on hydrodynamic during micro-mixing have only impact on the time of nanoparticles stability (induction period). Photo-active thin layers and membranes are synthesized for coupling membrane separation and photocatalytic reaction. Photocatalytic activities of thin layers and membranes are performed with an aqueous solution of acid orange 7. Significant increases of permeate flux are observed during the filtration of water and solution containing dye. Effects of concentration and pH are evaluated on permeation flux and photodegradation

Dissertação de mestrado em Física (área de especialização em Física Aplicada)
With the extensive use of chemicals produced through the development of technology, organic pollutants in water represent a major concern, as they constitute a potential risk for the ecosystem and human health. Furthermore, these compounds are extremely resistant to biological degradation processes and wastewater and drinking water treatment plants, causing their accumulation in water effluents. In this scope, Advanced Oxidation Processes arise as a possible solution, in particular, heterogeneous semiconductor photocatalysis. The primary aim of this study was to evaluate the effectiveness of immobilized titanium dioxide photocatalyst for the removal of pollutants from wastewater. Membranes of poly(vinylidene difluoride−trifluoroethylene) with 8% wt. P25 TiO2 nanoparticles were produced by solvent casting, with and without the inclusion of zeolites (NaY) to improve wettability, characterized and applied in the photocatalytic degradation of four micropollutants: the cationic dyes Methylene Blue, the antibiotic Ciprofloxacin, the anti-inflammatory Ibuprofen and the plastic precursor Bisphenol A. All the produced membranes possess a highly porous structure, with interconnected pores and a degree of porosity around 70%, with pore sizes ranging between 30 and 80 μm. The composites present the characteristic absorption bands of β PVDF and show unchanged polymer structure in comparison to the pristine polymeric membrane, even after four uses. The membranes with TiO2 and zeolites are more hydrophilic than the pristine membrane. The presence of TiO2 nanoparticles modify the hydrophobic nature of the membranes after subjected to ultra violet, as does the inclusion of zeolites. In the first use, the membrane with zeolites degraded Methylene blue with higher efficiency, ≃ 98% after 300 min, and a degradation rate of ≃ 0.044 min-1. The membrane without zeolites performed better in the degradation of Ciprofloxacin, ≃ 93% after 300 minutes, with a degradation rate of ≃ 0.010 min-1. Bisphenol A was not degraded and Ibuprofen seemed to generate by-products during the reaction. In the first use, after 300 minutes, Ibuprofen degraded ≃ 18 and ≃ 48% and Bisphenol A degraded ≃ 7 and ≃ 3%, using membranes with and without zeolites, respectively. Overall, reutilization of the membranes showed little to no efficiency loss after fourth degradations of Methylene blue, and a slight increase in the degradation of Ciprofloxacin, ≃ 98% with a reaction rate of ≃ 0.015 min-1, and of Ibuprofen, ≃ 66% with a reaction rate of ≃ 0.003 min-1, for membranes without zeolites after 300 minutes. The conjugation of these factors make these membranes suitable for photocatalytic degradation of micropollutants.
Vários poluentes orgânicos surgem na água como consequência do excessivo uso de químicos gerados com o desenvolvimento tecnológico. Estes poluentes constituem um potencial risco para o ecossistema e saúde humana. Além disso, são extremamente resistentes a processos de degradação biológica e estações de tratamento de águas residuais e água potável, causando a sua acumulação no meio aquático. Neste sentido, os Processos de Oxidação Avançados surgem como uma possível solução, em particular, a fotocatálise heterogénea com semicondutores. O principal objetivo deste estudo foi avaliar a eficácia da fotocatálise com dióxido de titánio imobilizado para a remoção de poluentes de águas residuais. Assim, membranas de poli(fluoreto de divinilideno-trifluoretileno) com 8% wt. de nanopartículas de TiO2 P25 foram produzidas por solvent casting, com e sem a implementação de zeólitos (NaY) de modo a melhorar a molhabilidade, caracterizadas e aplicadas na degradação fotocatalítica de quatro micropoluentes: o corante catiónico Azul de metileno, o antíbiótico Ciprofloxacina, o antiinflamatório Ibuprofeno e o percursor plástico Bisfenol A. Todas as membranas produzidas possuem uma estrutura porosa, com poros interconectados e um grau de porosidade de cerca de 70%, com tamanho de poros entre os 30 e os 80 μm. Os compósitos apresentam as bandas de absorção características da fase β do PVDF e mostram uma estrutura polimérica intacta, mesmo depois de quatro utilizações. As membranas com TiO2 e zeólitos são mais hidrofílicas do que a membrana pura. A presença de nanopartículas de TiO2 modifica a natureza hidrofóbica das membranas após sujeitas a luz ultra-violeta, assim como a inclusão de zeólitos. Na primeira utilização, a membrana com zeólitos degradou Azul de metileno com maior eficiência, ≃ 98% em 300 minutos, com uma velocidade de degradação de ≃ 0.044 min-1. A membrana sem zeólitos degradou Ciprofloxacina com mais eficiência, 93% em 300 minutos, com uma velocidade de degradação de ≃ 0.010 min-1. O Bisfenol A não foi degradado e o Ibuprofeno pareceu gerar sub-produtos aquando da reação. Na primeira utilização, o ibuprofeno degradou ≃ 18 e ≃ 48% em 300 minutos e bisfenol A degradou ≃ 7 e ≃ 3% em 300 minutos, usando membranas com e sem zeólitos, respetivamente. De uma forma geral, a reutilização das membranas mostrou pouca ou nenhuma perda de eficiência após quatro degradações de Azul de metileno, e um ligeiro aumento na de Ciprofloxacina, ≃ 98% com uma velocidade de reação de ≃ 0.015 min-1, e de Ibuprofeno, ≃ 66% com uma velocidade de reação de ≃ 0.003 min-1, para membranas sem zeólitos após 300 minutos. A conjugação destes fatores faz destas membranas apropriadas para a degradação fotocatalítica de micropoluentes.

The work developed in this thesis focused on optimizing membrane processes and in the development of a novel hybrid photocatalytic membrane reactor to treat olive mil wastewaters. The traditional Mediterranean diet, known for being a rich and healthy diet, uses olive oil as its main source of fats. Therefore, in the Mediterranean region, there is an annual discharge of 30 million m3 of the wastewaters produced by this industry into the environment. Olive mill wastewaters are a highly polluted effluent produced in olive oil industries, representing an environmental hazard if not treated properly. These effluents present low pH and a high concentration of solids, oil and organic compounds such as organic acids, lipids and alcohols. The presence of phenolic compounds hinders the biological treatment of these wastewaters. Membrane separation processes stand out as promising treatment approaches and their application has expanded during recent decades for the treatment of wastewaters, as a result of increasingly stringent regulations in wastewater discharge and continuing improvements in membrane technology. However, wide acceptance of membrane processes by industries is limited by membrane fouling. Fouling is caused by the accumulation of rejected oil, suspended solids and other components of the wastewaters on the membrane surface and intrapore structure. Fouling results in flux decline and low membrane lifetime due to the need to perform frequent cleanings. When compared with polymeric membranes, ceramic membranes present several advantages such as higher thermal stability, mechanical resistance and chemical resistance, and thus can be applied in extreme aggressive environmental conditions. These properties allow for a better control of membrane fouling since higher pressures can be employed during backpulse and backwash procedures, and cleanings can be performed with stronger chemicals, without compromising the membrane lifetime. In the present work, the treatment of the olive mill wastewaters was mostly performed with ultrafiltration ceramic membranes made of silicon carbide. Different strategies to overcome the problem of fouling were studied: (a) the optimization of operating conditions, conducted under controlled pressure / controlled permeate flux, allowing for a sustainable performance, and the use of backpulse and backwash strategies at pilot scale and (b) the modification of the surface of the silicon carbide membranes to obtain a photocatalytic membrane with a lower molecular weight cut off and higher hydrophilicity. The new photocatalytic membranes developed were obtained using a sol-gel process combining titanium dioxide, silicon dioxide and silicon carbide. These membranes proved to have photocatalytic activity and were thus tested in a new hybrid reactor. The extremely efficient removals of the compounds analyzed and the lower fouling potential observed, showed that the developed photocatalytic membranes and the novel hybrid reactor are highly promising solutions to be used in the treatment of olive mill wastewaters, as well as in a variety of other wastewaters and water matrices.

碩士
國立臺北科技大學
有機高分子研究所
102
In this study, we firstly prepared polyacrylonitrile (PAN)-ZnO/Ag composite ES fiber membranes consisting of pineal-type, flower-type, and sea-urchin-type ZnO morphologies by using ES technique, hydrothermal synthesis, and Ag reduction. The effects of the various ZnO structures on the fiber morphologies, photocatalytic efficiency, UV protection, and mechanical properties as well as how the additive Ag enhanced antimicrobial activity. Our results indicated that the photocatalytic and UV-protection efficiency of PAN-ZnO/Ag ES fiber membranes can be altered by varying the morphology of ZnO. The various ZnO architectures exhibited differences in photocatalytic activity and UV-shielding efficiency, and were ranked as follows: sea-urchin > flower- > pineal-type. Sea-urchin-type ZnO features higher surface-to-volume ratio than other architectures do because of its distinctive structure, thus yielding higher performance. The present study demonstrated that self-standing PAN-ZnO/Ag composite fiber membranes, especially those with the sea-urchin-type ZnO structure, can be applied in multifunctional textiles such as water purification filters and antibacterial and UV-shielding clothes.

碩士
逢甲大學
環境工程與科學學系
107
Neonicotinoid is one of the most widely used insecticides in the world. It protects crops with insecticides, but it also affects the life of bees and leads to crop harvesting. It is mainly represented by midacloprid, Thiamethoxam, Acetamiprid and Clothianidin. Experiments were carried out with these four insecticides. Therefore, this study is divided into two parts. The first part is to prepare metal TiO2, doped with Ferric nitrate, Silver nitrate and simultaneously doped with iron and silver to degrade neonicotinoid insecticides. Photocatalyst analysis is performed by reflection spectroscopy, X-ray diffraction analysis, etc., and the second part is used for film preparation by using a recovery material of cellulose triacetate to separate photocatalysts after photodegradation, and to use a particle size analyzer and nano particles. Tracking the performance of the analyzer after separation, the photocatalyst analysis, photodegradation effect and separation effect are used to obtain the optimal conditions for photocatalytic degradation and separation.

Membrane filtration has revolutionised water treatment, enabling safer provision of drinking water due to its high efficiency to block human infectious pathogens commonly present in raw water sources. Accumulation of substances on membrane surfaces and pores during operation, referred to as fouling, is considered one of the biggest barriers to wider adoption of membrane technology in water treatment. Maintaining continuous low-pressure filtration requires significant amounts of chemicals to clean off the accumulated fouling substances. Chemical use comes with economic and environmental costs associated with acquisition, transportation, storage, usage and disposal of chemicals, especially in disadvantaged and remote communities. By conservative estimates, supply of household water to a remote community of 100 people using a membrane system would require continuous supply of at least 10 L of polyaluminium chloride coagulant and 4 L of sodium hypochlorite (in concentrated form) every month. The main aim of this thesis is to demonstrate a sustainable, innovative, low cost membrane solution harnessing conveniently available solar energy to offset these chemical demands. Coating membrane substrates with semiconductor photocatalysts such as titanium dioxide (TiO2) is an effective method for mitigating fouling in membranes through induced superhydrophilicity, enabling cleaning from the available water without chemicals. TiO2 also enables water contaminant degradation and pathogen inactivation through reactive oxygen species (ROS) facilitated advanced oxidation. Despite these well- known effects, a major challenge limiting practical adoption comes from light absorption and scattering by the turbid contaminants in the feed stream before reaching the TiO2. This thesis proposed a novel solution to this challenge by transmitting light to the TiO2 through cheap porous borosilicate glass substrates with between 10% and 80 % transmission in the 340-400 nm wavelength range relevant to activating commercial Degussa P25 TiO2 photocatalyst. The concept novel membrane was produced using commercial glass substrates modified by simply dip- coating and heat sintering Degussa P25. The formed asymmetric membrane’s mean pore size was measured at 0.5 μm, which classifies the membrane as a microfiltration (MF) membrane, which are utilised in the industry as a barrier to water-borne pathogens such as protozoa and bacteria, and partially to viruses. To demonstrate the membrane’s photocatalytic ability, photocatalytic reactions stimulated by a UV lamp (365 nm peak) facing the glass substrate side in an ex-situ setup led to a 52% degradation of methyl orange in aqueous solution, being only slightly lower than the 58% degradation when the TiO2 active layer faced the UV light source. The membrane was then operated in-situ using a custom module with a quartz window and UV LED installed on the permeate side, enabling simultaneous microfiltration of model fouling solutions. Results showed significant reductions in trans-membrane pressure (TMP) rise rates directly linked to UV light application. Specifically, UV light was responsible for up to 3.0-fold reduction in total filtration resistance and up to 4.2-fold reduction in irreversible fouling indices. Testing continued on simulated indirect solar light with a real non-potable water. The membrane itself showed up to 94% turbidity removal and up to 80% total organic carbon (TOC) rejection. The sunlight was directly responsible for an 8-fold reduction in the irreversible fouling index. The significant practical findings were followed by an investigation to confirm the fundamental basis for improvement. Analysis by scanning electron microscopy (SEM) coupled with fouling modelling showed the beneficial photocatalytic fouling reduction effects during microfiltration stemmed from reduced intrusion of organic fouling material inside the TiO2 membrane pores, as well as reduced cake layer resistance. Analysis of results and photocatalysis mechanisms from literature led to the conclusion this was due to both superhydrophilicity minimising organic attractions to the surface and photocatalytic oxidation of organics approaching the surface. The potential for advanced oxidation to participate in reacting with organic matter surfaces attracted to the membrane was confirmed from a measurable increase in the presence of hydroxyl radicals using para-chlorobenzoic acid (pCBA) probe experiments. The practical benefits for industry towards chemical consumption and energy reduction were also measured. For example, a 4.5-fold extension to the time needed for a clean-in-place (CIP) was realised when the membrane was operated in photocatalytic mode. A 50% reduction in filtration pump electricity demand was also calculated, which translates to a reduction in height of the feed water for a flux of 300 L/m2/h from 8.6 m to 3.7 m over a 5 hour run. Future work suggested includes using recycled glass to improve affordability and minimise glass manufacture environmental impact, as well as experimentally establishing the relationship hydroxyl radical concentration and TOC reduction. Optimisation of the glass material for enhancing light transmission efficiency and development of porous glass monoliths like current commercial ceramic membranes for full-scale use, as well as optimisation to increase contaminant degradation are also suggested.

Water quality from surface sources is fast deteriorating due to pollution from organic compounds. Among the organic compounds are chlorophenols, which are described as priority pollutants because of their detrimental effects. One way of removing them from water is by using membranes. However direct removal of chlorophenols using membranes is limited due to the inherent problem of membrane fouling. The thesis describes fabrication of thin film composite membranes modified with Ag-TiO2 and Ag-ZnO for enhancing filtration properties of the membranes for removal of 2-CP and 2,4-DCP and improving the antifouling properties of the modified membranes. Chlorophenols, 2- CP, 2,4-DCP and 2, 4, 6-TCP were determined from Vaal and Klip River using SPE- HLPC method. The SPE - HPLC method was validated by determining breakthrough volume, repeatability, reproducibility, linearity, MDL and LOQ. Nanoparticles (NPs), Ag, ZnO and TiO2 and nanocomposites (NCs), Ag-TiO2 and Ag-ZnO were synthesized using precipitation method and chemical reduction for Ag. The NPs and NCs were characterised using UV-Vis, FTIR, XRD, SEM and EDX. The synthesised NPs and NCS were evaluated for photocatalytic degradation of 2-CP and 2,4-DCP, antimicrobial activity against E.coli. and toxicity against Daphnia magna. Nanocomposites were then embedded into the PA thin film membrane surface using interfacial polymerisation and PES as a support material to produce the antifouling Ag-TiO2/PA-TFC and Ag-ZnO/PA-TFC membranes. The control PATFC membrane was prepared with no added NCs to the membrane. The membranes were characterised using ATR-FTIR, contact angle, SEM and AFM. The performance of the membranes was tested using permeation flux (using pure water and 2-CP / 2,4-DCP solutions as feed) against the neat PA-TFC membrane. Membranes were further tested for rejection of 2- CP and 2, 4 – DCP, antifouling properties and flux recoveries. The stability of the antifouling properties of the membrane was evaluated through silver release test. The performance of the membranes was tested using real water samples from Vaal and Klip Rivers. The SPE-HPLC method was repeatable, reproducible with % RSD less than 5%. Linearity range of (0.1-50 µg/ L) and recoveries of spiked water samples of more than 97% for 2-CP and 2,4-DCP but lower at 64 and 75% for 2.4.6-TCP were achieved. The Ag, TiO2 and ZnO NPs showed characteristic peaks of NPs with UV-Vis. The absorption peaks were all blue shifted due to quantum confinements. The crystalline structures were confirmed as face centred cubic, anatase and hexagonal wurzite for Ag, TiO2 and ZnO respectively. The morphology as observed from SEM showed spherically shaped nanoparticles with average sizes of 68.25 ± 4.7 and 50.92 ± 3.39 nm for Ag and TiO2 respectively. The ZnO NPs were rod -like shaped with average length = 603 nm ± 50.4 and a width = 82.92 ± 5. 40nm. Successful incorporation of silver into the TiO2 and ZnO structures was confirmed by elemental analysis, EDX. From SEM images, silver particles were distributed around TiO2 particles and ZnO rods. The presence of silver showed a remarkable improvement in photodegradation of 2-CP and 2,4-DCP from less than 40% to 86% with 2, 4- DCP. Silver modified TiO2 and ZnO showed antibacterial activity against E.coli. with minimum concentration of inhibition as low as 1.56 mg/L for both Ag-ZnO (5) and Ag-TiO2 (5). Silver was more toxic against Daphnia magna than Ag-ZnO (5) and AgTiO2 (5). The polyamide layer was confirmed by the presence of the amide I peak at 1650 cm1 and 1670 cm-1 in the Ag-TiO2/ PA-TFC and Ag-ZnO/ PA-TFC membranes. The appearance of NCs particles spread across the surface of the thin layer of the membranes as observed from surface SEM images confirming their incorporation into the PA layer. The presence of the NCs in the membranes improved water flux, water permeation, rejection of 2- CP, and 2,4-DCP, antifouling properties of the membranes and flux recoveries of more than 93 % was achieved. Silver release test revealed that Ag-ZnO/PA-TFC membrane performed better than AgTiO2/PA-TFC membrane because of the steady release of silver, which shows long lasting antifouling properties. When applied to real water samples from Vaal and Klip River, the prepared membranes showed better antifouling properties than the neat PA-TFC membrane

This research work discusses the removal of organic pollutants specifically diclofenac and acid blue-25 using chalcogenide semiconductors. Semiconductors are materials that absorb light of specific energy and potentially degrade these organic pollutants into smaller compounds that are not toxic such as carbon dioxide and water.
Civil and Chemical Engineering

碩士
國立臺灣科技大學
化學工程系
93
In this research, ceramic filter tubes were used as the supporting material for coating two types of titanium dioxide catalyst, Degussa P-25 and photocatalyst synthesized by thermal hydrolysis method. Solutions contained organic dyes were allowed to flow over the traditional photocatalytic film reactor or flow through this new photocatalytic membrane reactor. The reaction rates of the new photocatalytic membrane reactor are about three to five times faster than those of the traditional photocatalyic film reactor. This was caused by forced convection flow of organic dyes in the photocatalytic membrane reactor which would reduce the mass transfer resistance. The operational parameters studied included pH value, filtration pressure, light intensity, temperature and the initial dye concentration. A reaction kinetic model was established to describe the behavior of photocatalytic membrane process.

This work aims at modelling and evaluating a new type of photocatalytic reactors, named fixed-bed photocatalytic membrane reactor (FPMR). Such reactors are based on the deposition of a thin layer of photocatalysts on a permeable substrate by filtration. This layer serves as a photocatalytic membrane, named fixed-bed photocatalytic mem-brane (FPM), which is perpendicularly passed by the reactant solution and illuminated by a suitable light source. One advantage of FPMs is their renewability. The model, which was developed for this reactor, relates the overall reaction rate in the FPM with the intrinsic reaction kinetic at the catalyst surface and accounts for light intensity, structural and optical layer properties as well as the mass transfer in the pores. The concept of FPMR was realised by using a flat sheet membrane cell. It facilitated principal investigations into the reactor performance and the validity of the model. For this purpose, the photocatalytic degradation of organic compounds, such as meth-ylene blue and diclofenac sodium, was conducted at varying conditions. Pyrogenic ti-tania was used as a photocatalyst. The experimental data support the developed mod-el. They also indicate a significant impact of the flow conditions on the overall photo-catalytic activity, even though the Reynolds number in the FPM was very small; the to-tal mass transfer rate in the FPM amounted to more than 1.0 s−1. The experiments also showed a sufficient structural strength of the FPM and photocatalytic stability. In addi-tion, the renewal and regeneration of FPMs was successfully demonstrated. Furthermore, another FPMR was designed by means of submerged ceramic mem-branes. This reactor was mainly used to assess the effectiveness and efficiency of FPMRs at the example of the photocatalytic degradation of oxalic acid. The correspond-ing reactor was run closed loop and in continuous mode. The effectiveness of the reac-tor was evaluated based on common descriptors, such as apparent quantum yield, photocatalytic space-time yield and light energy consumption. The results showed that the FPMR based on submerged ceramic membrane had a higher efficiency than other reported photocatalytic reactors. The comparison of the different modes of operation revealed that the closed loop FPMR is most efficient with regard to light energy con-sumption. Finally, this work discusses the up-scaling of FPMRs for industrial applications and proposes a solution, which can e.g. be employed for wastewater treatment or CO2 conversion.:Abstract iii Kurzfassung v Acknowledgment vii Contents ix Nomenclature xiii 1 Introduction 1 1.1 Motivation 1 1.2 Aim and objectives of the work 3 1.3 Thesis outline 3 2 Heterogeneous photocatalytic reactors 5 2.1 Introduction to photocatalysis 5 2.2 Processes in heterogeneous photocatalysis 6 2.2.1 Optical phenomena 7 2.2.2 Mass transfer 8 2.2.3 Adsorption and desorption 9 2.2.4 Photocatalytic reactions 10 2.2.5 Factors affecting heterogeneous photocatalysis 12 2.3 Photocatalytic reactor systems towards water treatment 16 2.3.1 Introduction to photocatalytic reactors 16 2.3.2 Development of photocatalytic reactor designs 17 2.3.3 Quantitative criteria for evaluating photocatalytic reactor designs 21 2.4 Cake layer formation in membrane microfiltration 22 2.4.1 Suspension preparation 22 2.4.2 Cake layer formation 23 2.5 Fluid flow through a fixed bed of particles 25 2.5.1 Pressure drop through a fixed-bed 25 2.5.2 Liquid-solid mass transfer correlation in fixed-bed 25 3 Concept and mathematical modelling of FPMRs 29 3.1 Concept of fixed-bed photocatalytic membrane reactors 29 3.2 Modelling of fixed-bed photocatalytic membrane reactors 31 3.3 Model sensitivity analysis 37 3.4 Chapter summary 39 4 FPMR realised with flat sheet polymeric membrane 41 4.1 Introduction 41 4.2 Materials and set-up 41 4.2.1 Materials 41 4.2.2 Experimental set-up 43 4.3 Experiments and methods 48 4.3.1 Formation of fixed-bed photocatalytic membrane 48 4.3.2 Reactor performance 50 4.3.3 Parameters study and model verification 53 4.3.4 Catalyst layer characterisation 56 4.3.5 Measurement and evaluation of photocatalytic activity of FPM 59 4.4 Results and model verification 60 4.4.1 Reactor performance 60 4.4.2 Influence parameters 71 4.4.3 Model verification 79 5 FPMR realised with submerged ceramic membrane 92 5.1 Introduction 92 5.2 Materials and reactor set-up 93 5.2.1 Reactor set-up 93 5.2.2 Chemicals 97 5.3 Experiments and methods 97 5.3.1 Formation of fixed-bed photocatalytic membranes 97 5.3.2 Photocatalytic performance 97 5.3.3 Parameter study 98 5.3.4 Reactor model for calculating reaction rate constant of FPM 99 5.3.5 Comparison of different reactor schemes 102 5.4 Results and discussions 105 5.4.1 Reactor performance 105 5.4.2 Consistency of CPMR and LPMR data 107 5.4.3 Influence of catalyst loading 108 5.4.4 Influence of permeate flux and light intensity 109 5.4.5 Reactor efficiency 111 5.4.6 Comparison of different reactor schemes 113 5.5 Proposed up-scaled FPMR systems 113 5.6 Concluding remarks 116 6 Conclusion and outlook 118 6.1 Summary of thesis contributions 118 6.2 Discussion and outlook 120 References 122 List of Figures 134 List of Tables 138 Appendix A Calibration 139 A.1 Distribution of light intensity on the surface of catalyst layer 139 A.2 Concentration and absorbance of diclofenac 141 A.3 TOC concentration and electrical conductivity of oxalic acid 141 A.4 Concentration and absorbance of methylene blue 142 Appendix B Mathematical modelling 143 B.1 Influence of axial dispersion on the reaction rate 143 B.2 Special case 146 Appendix C Comparison the photocatalytic activity of TiO2 and ZnO 147 Appendix D Mathematical validation of model for LPMR and CPMR 148 D.1 Model for LPMR (cf. Eq. (5 12)):148 D.2 Model for CPMR (cf. Eq. (5 17)) 149 Appendix E Particle size distribution 151

Dissertação de Mestrado Integrado em Engenharia Química apresentada à Faculdade de Ciências e Tecnologia
AbstractIn recent decades, issues related to water quality and quantity have been identified as one of the major problems faced by humanity. This is all due to pollution of surface and underground water resources and excessive consumption. Thus, and given the importance for the subsistence of life on the planet, protecting and preserving water resources is essential. Wastewater recovery maybe seen as a viable source of water.Wastewater treatment plants have proven to be unable to remove emerging contaminants using conventional treatment methods, disrupting the natural balance of the ecosystems where these contaminants are released. Parabens are synthetic chemicals commonly used as antimicrobial and antifungal agents and as preservatives in various pharmaceutical and personal care products. On the other hand, microbiological contaminants can be pathogenic and harmful to both animals and humans. E. coli and S. aureus are, respectively, gram-negative and gram-positive bacteria that can cause serious poisoning and infection when in contact with animals and humans.Firstly, the removal of a mixture of three parabens, methylparaben, ethylparaben and propylparaben through photocatalytic oxidation was studied. This process consists on the production of hydroxyl radicals with the help of a photocatalyst, more precisely TiO2, immobilized on a polymeric surface under solar radiation. The aqueous solutions where the parabens were dissolved had submerged polymeric membranes of different natures, two polyurethanes (Desmopan 481 and 3330A) and a silicone (PDMS). In addition to studying the polymeric nature of the support, the effect of the immobilization technique applied was also studied, techniques such as plasma immobilization, photocatalyst entrapment and both techniques simultaneously applied on the same membrane. In order to study the adsorption capacity as well, and compare with the degradation results upon exposure to sunlight for one hour, the membranes were placed in the dark.Hence, was possible to observe that the PDMS membrane showed explicit results on the influence of both immobilization technique compared to a blank membrane, and the results to sunlight and dark. Since the best results were obtained by plasma photocatalyst immobilization and the technique that combines the other two techniques together, and since the latter obliges to an additional expense related with the photocatalyst, plasma immobilization was chosen for a later study.Taking into account the conclusion made by the first study, the PDMS membrane and plasma technique were selected to study the variation of experimental conditions. Conditions such as the exposure time to UV radiation for photocatalyst fixation (15, 30 and 60 minutes) and the concentration of aqueous solution (70mg/L, 140mg/L and 280 mg/L) where the membranes are submerged and placed in the radiation chamber.Thusly, by analyzing the results obtained for paraben degradation, it is possible to conclude that the conditions that had better results were both for a radiation time of 30 minutes and for aqueous solutions concentration of 70 mg/L and 140 mg/L. In this case, the solutions were exposed to sunlight for two hours.Lastly, membrane antibacterial activity, for E. coli and S. aureus, was also studied for blank PDMS membranes and for all types of photocatalyst immobilization. For the E. coli study, it was registered a decrease in bacterial viability for photocatalyst entrapment and photocatalyst entrapment in conjunction with the plasma technique. In the first case, the decrease as residual (less than 5%), but in the second case, was obtained a reduction of 40% for bacterial viability. For the S. aureus study was registered a decrease in bacterial viability for ohotocatalyst entrapment method of 10%.
Nas últimas décadas, as questões relacionadas com a qualidade e quantidade de água têm sido identificadas como um dos principais problemas enfrentados pela humanidade. Isto acontece devido à poluição de recursos hídricos, superficiais e subterrâneos, e ao consumo excessivo. Desta maneira, e tendo em conta a importância para a subsistência da vida no planeta, a protecção e preservação dos recursos hídricos é essencial. A recuperação das águas residuais é, desta maneira, vista como uma fonte de água viável.As estações de tratamento de águas residuais demonstraram-se incapazes de remover contaminantes de carácter emergente, através dos métodos de tratamento convencionais, resultando na perturbação do balanço natural dos ecossistemas onde estes contaminantes são inseridos. Os parabenos são químicos sintéticos comummente usados como agentes antimicrobianos e antifúngicos e também como conservantes em vários produtos farmacêuticos. Por outro lado, os contaminantes microbiológicos podem ser patogénicos e nocivos tanto para animais como para seres humanos. E. coli e a S. aureus são bactérias, gram-negativa e gram-positiva, respectivamente, que podem provocar intoxicações e infecções graves quando em contacto com animais e seres humanos.Inicialmente, foi estudada a remoção de uma mistura de três parabenos, metilparabeno, etilparabeno e propilparabeno através da oxidação fotocatalítica. Este processo consiste na produção de radicais hidroxilo com a ajuda de um fotocatalisador, neste caso o TiO2, imobilizado numa superfície polimérica, sob a radiação solar. As soluções aquosas onde os parabenos estavam dissolvidos, possuíam, submersas, membranas poliméricas de diferentes naturezas, duas poliuretanas (Desmopan 481 e 3330A) e um silicone (PDMS). Para além do estudo à natureza do suporte polimérico, foi também estudado o efeito da técnica de imobilização utilizada, técnicas essas que são a imobilização por plasma, o aprisionamento do fotocatalisador e as duas técnicas em simultâneo na mesma membrana. De maneira a estudar também a capacidade de adsorção, e comparar com os resultados da degradação aquando da exposição à luz solar durante uma hora, as membranas foram colocadas no escuro.Assim sendo, foi possível observar que o PDMS apresentava resultados explícitos da influência tanto da técnica de imobilização comparada à membrana em branco, como dos resultados à luz solar e no escuro. Uma vez que as técnicas que apresentavam melhores resultados, e semelhantes, eram a de imobilização de fotocatalisador por plasma e a técnica que consistia na junção das duas técnicas utilizadas e como esta última implica um gasto adicional de fotocatalisador, foi escolhida para um estudo posterior a imobilização por plasma.Tendo em conta o que foi concluído com o primeiro estudo foram então selecionadas a membrana PDMS e a técnica de plasma para efectuar um estudo à variação das condições experimentais. Condições estas que são o tempo de exposição à radiação UV para a fixação do fotocatalisador (15, 30 e 60 minutos) e à concentração da solução aquosa (70 mg/L, 140 mg/L e 280 mg/L) onde as membranas são submersas e posteriormente colocadas na câmara de radiação.Desta maneira, analisando os resultados obtidos para a degradação dos parabenos, é possível conclui que as condições que conferiram melhores resultados experimentais foram ambas para um tempo de radiação de 30 minutos e com concentração da solução aquosa de 70 e 140 mg/L, neste caso, durante duas horas de exposição solar.Por último, foi também estudada a actividade antibacteriana das membranas para o caso das membranas de PDMS em branco e para todos os tipos de imobilização de fotocatalisador, sendo as bactérias em causa foram a E. coli e a S. aureus. No estudo feito à E. coli, foi registado uma diminuição da viabilidade bacteriana para o aprisionamento de fotocatalisador e para o aprisionamento de fotocatalisador juntamento com a técnica de plasma, no primeiro caso, a diminuição foi residual (inferior a 5%), mas no segundo caso, foi obtida uma redução da viabilidade bacteriana de 40%. Já para o estudo realizado à S. aureus, foi registada uma diminuição mais acentuada da viabilidade bacteriana para o método de aprisionamento de fotocatalisador, de cerca de 10%.

碩士
中原大學
生物環境工程研究所
103
Nowadays,treatment program of membrane is the choice for industrial, municipal water and wastewater treatment with wide using, Permanent flux decline, loss of product quality, affecting water quality, and reduce the life of film are the main problem because of membrane fouling accumulation with long operating time. Literature shows that nano-materials with photocatalyst coating and coat on membrane surface can enhance hydrophilicity and reduce effect of fouling. In this study, PVDF membrane was reformed by low-temperature plasma modification and coated with N-doped ZnO on PVDF membrane. Change characteristics of membrane surface and Minimize fouling effects and remove them. In experiment of adding dose, shows that photocatalytic degradation of efficiency tend to be slower after add more than 0.5g of N-doped ZnO; In experiments of different Reactive Black 5(RB5) initial concentrations shows that RB5 concentration of is higher, visible light transmittance is lower. After N-doped ZnO coating on the membrane, the efficiency of photocatalytic degradation RB5 obviously reduced, but still has capacity of photocatalysis. In the experiment of the simulation of pollutant membrane fouling that chooses amount of coating for 0.25g, 0.5g, 1g with N-doped ZnO membrane to operate. In alginic acid placing, unmodified PVDF films still in fouling state in the end, the highest recovery rate is coated 0.5g of N-doped ZnO membrane that can reach to 96% of water flux test. In bovine serum albumin placing, unmodified PVDF and coating with membrane of 0.25g of N-doped ZnO still in fouling state in the end, the highest recovery rate is coated 1G of N-doped ZnO membrane that can reach to 85% of water flux test. In the activated sludge test, recovery rate in Physical cleaning stage of all the N-doped ZnO flux are better than PVDF membrane and recover to the initial flux in illumination satge. It shows that N-doped ZnO has certain efficiency on different kinds of antifouling, the flux recovery of N-doped ZnO membrane in different pollutants accumulated can reach more than 80% after light for 60 minutes.

博士
國立臺灣科技大學
化學工程系
94
The purpose of this research was to study the effects of solution pH on the photoelectrochemical properties of TiO2 photoelectrode and the photocatalytic reactions of dyestuffs in aqueous solution using photocatalyst membranes. The open circuit voltage and the short circuit photocurrent of TiO2 photoelectrode increased as solution pH decreased and indicated more photoelectrons were generated in acidic solutions. The response times reaching half maximum photovoltage and photocurrent were determined to be faster in acidic solutions than those in alkaline solutions, indicating higher electron diffusion occurred in acidic solutions. The effect of electrolyte solution pH, fluid pressure and UV irradiation on the tangential streaming potential (TSP) and filtration streaming potential (FSP) of Degussa P-25 titanium dioxide membrane were examined. Both TSP and FSP measuring systems for TiO2 membrane were developed. Experimental results depicted TSP and FSP measurements were sensitive to solution pH, temperature, fluid pressure and UV irradiation. Zeta potentials of TiO2 membranes calculated with TSP data were different from those of TiO2 suspensions measured by electrophoretic light-scattering technique, but the isoelectric point (pHiep) was measured to be almost the same value of 6.8. The pH drifts (difference of initial and final pH) were observed during the TSP measurements of TiO2 membranes. A modified model was developed to calculate the change in Fermi energy of the electrolyte/TiO2 membranes system presented at different solution pH levels. A hysteresis phenomenon was found that two zeta potentials were observed at the same pH through different pH adjustment paths. Slight decreases of TSP (<15mV) were observed in acidic solutions under UV irradiation; however, more considerable decreases of FSP (20~60mV) were examined in both acidic and alkaline solutions. The FSP increased with increasing filtration pressures and exhibited an exponential decay with increasing light intensity. The ultraviolet light emitting diode (UV-LED) was used as the UV light source for the photocatalytic decomposition of Reactive Red 22 (RR 22). The temporal behavior of the photocatalytic decomposition of RR 22 in aqueous solution by the UV-LED/TiO2 with a rectangular planar fixed-m reactor operated in a recirculation mode was studied under various conditions including initial dye concentration, periodic illumination, light intensity, and arrangements of TiO2 coating. The decomposition of RR 22 in aqueous solution by TiO2 photocatalytic processes with the UV-LED was found to be technically feasible with a high TiO2 coated weight (1.135g) and low pH value (pH 2). A Langmuir-Hinshelwood type kinetic equation was adequate for modeling the photocatalytic decomposition of RR 22 by the UV-LED/TiO2 photocatalytic processes. The experimental results indicated that the photonic efficiency with periodic illumination was much higher than those with continuous illumination. The photonic efficiencies with the QLC (quartz-liquid-catalyst) arrangement were higher than those with the QCL (quartz-catalyst-liquid) arrangement for experiments conducted at lower applied light intensity; however the photonic efficiencies for these two arrangements were nearly identical for experiments conducted at higher light intensities. The coating of 0.5 gram of Nafion per gram of TiO2 was enough to reduce the zeta potential of Nf/TiO2 to less than -20mV in aqueous solution and exhibited a hydrophobic surface that might decrease the adsorption and photocatalytic decomposition of dye. Experimental results on the adsorption and photocatalytic decomposition of RR22 and BR2 indicating that the charges of TiO2 surface and reactant dye markedly influence the reaction rate. The photocatalytic decompositions of RR22 using TiO2 were favored to occur in acidic conditions and exhibited a minimum decomposition rate near the isoelectric point of TiO2. Nevertheless, no obvious RR22 decompositions were found in experiments conducted using Nf/TiO2. Decompositions of BR2 using both TiO2 and Nf/TiO2 were more favorable in alkaline conditions; however, decompositions of BR2 were found to be decreased in experiments conducted using Nf/TiO2.

碩士
中原大學
生物環境工程研究所
104
In this study, the waste fluorescence powder used acid leaching to rare earth metal leach out and doped with titanium dioxide (TiO2). This reduced the TiO2 energy gap, making the light source can be changed to visible light from ultraviolet light, which can effectively reduce energy problem. Membrane treatment procedure for the widespread use of the current technology. Literature indicated by photocatalyst coating material was applied on the membrane hydrophilic, it could effectively improve performance and reduced the impact of fouling materials. In this study, the modified PVDF membrane by low temperature plasma and preparation of lanthanum-doped titanium dioxide coated on it. The modified membrane surface properties and photocatalytic reaction which reduced the fouling material and eliminate it. The results showed that in acid leaching, use 5M nitric acid and solid-liquid ratio is 1: 5；1M HNO3 → 5M HNO3 → 5M HCl combination leaching 6 hours can obtained better lanthanum content. Photocatalytic reaction results showed that the amount of additive with 1wt% lanthanum had best additive amount of experiments. It showed lanthanum-doped titanium dioxide the amount exceeds 3wt%, the photocatalytic degradation efficiency tends to be slow. Experimental test different light sources the display blue light was best, and tested for their photocatalyst repeatability results show times can be repeated up to 11 times. One wt% La-TiO2 coated on the membrane, its photocatalytic degradation efficiency of the dye decreased, but still has the ability of photocatalytic. La-TiO2/PVDF membrane is hydrophilic but it lead to increased pressure through the mold.

博士
國立交通大學
環境工程系所
97
A suspended photocatalytic oxidation system offers lots of active sites for photocatalytic oxidation, simplifies UV light arrangement, and obviates the complexities of fixing a photocatalyst onto a substrate. However, effective and economic separation of photocatalyst from the slurry system is still a problem to be addressed. In this study, a novel photocatalytic membrane reactor (PMR) has been developed based on material selection, system development, and application study. The non-woven membrane (or called macroporous membrane) instead of microporous membranes, e.g. MF or UF, was proposed in a PMR to separate photocatalysts from slurry and to photodegrade model compounds such as methylene blue, 4-chlorophenol, and secondary effluent. Three major parts including material characteristics of non-woven membrane and their filtration behavior, the development of the hybrid system from batch and continuous tests and the application studies of the hybrid system are emphasized in this study. Three different pore sizes of non-woven membrane, 0.2, 2.0, and 20.0 µm, were applied to determine the most optimum filtration performance in terms of specific flux and residual turbidity in permeate. The results showed that when the pore size of the non-woven membrane was equal to or smaller than that of secondary particles of photocatalyst, a high specific flux and low turbidity in permeate were obtained simultaneously. Therefore, a 2.0 µm pore size of the non-woven membrane was selected for further study. The filtration resistance in non-woven membrane was determined by the operating conditions, e.g. concentration of photocatalyst, pH value, air intensity and applied flux. The filtration resistance was more and more significant when applied flux was 3.0 m3/m2/day or more. Because the pore size of the non-woven membrane was large (i.e. 2.0 µm) and the filtration resistance from membrane itself was minor, the filtration resistance was dominated by porous cake formation, about 80%, and the rest of 20% was shared equally by reversible and irreversible pore blocking or pore narrowing. Under the circumstances, the thickness of porous cake formation was controlled by optimum operating conditions to obtain stable applied flux and low TMP. The photodegradation characteristics of methlyene blue and filtration behavior using a 2.0 µm pore size of non-woven membrane were demonstrated in batch and continuous modes. The photodegradation of methlyene blue followed by pseudo-first-order reaction kinetics was proposed, because a low concentration of model compound was used. In continuous mode, the concentration of SS in hybrid system was decreased with increasing flow rate (or applied flux) resulting in the formation pf porous cake layer on the surface of non-woven membrane. Then, TMP was maintained around 3.5 kPa under optimum air intensity to induce a crossflow velocity after cake layer was formed. The inactivation of photocatalyst and the photodegradation performance of organic fouling materials were focused on the application study of this hybrid system, when 4-cholophenol and secondary effluent were used, respectively. The inactivation or toxicity of photocatalyst was no obvious when the chloride ion was formed after photodegradation of 4-chlorophenol, because the tremendous active sites onto the surface of the suspended photocatalyst could offer and suitable operating conditions, e.g. pH value and dissolved oxygen, were performed. Moreover, organic fouling materials, e.g. biopolymer and humic acids, in the secondary effluent were photodegraded using this hybrid system to improve the filtration ability of UF membrane by a batch stirred cell test. Therefore, the proposed hybrid system in which a non-woven membrane could replace microporous membrane in a PMR system was used to separate completely suspended photocatalysts and to photodegrade effectively model compounds. At the same time, low TMP and stable applied flux in this hybrid system was expected to reduce dramatically membrane fouling potential after the optimum pore size of non-woven membrane was selected and the porous cake layer was formed on the surface of non-woven membrane.

"Limited attention has been given to the presence of fungi in the aquatic environment when compared to other microorganisms such as bacteria and virus. Our previous research showed that fungi occur widely in drinking water sources and described many fungi species that have not been previously reported in the aquatic environment. Moreover, many filamentous fungi species present in water were found to be able to grow at high temperatures and have conidia measurements lower than 5 µm, being therefore considered as potential pathogenic species to humans and animals. (...)"

碩士
中原大學
化學工程研究所
106
Photocatalytic-Membrane Reactor (PMR) has been widely used in wastewater removal in recent years. Compared to batch photodegradation system, not only photocatalyst can be separated from liquid phase in PMR, but also the removal efficiency can be increased significantly. In this study, we design a PMR system to remove wastewater containing methyl blue, methyl orange, phenol, and mixed organic dyes. In this study, phosphorus-doped graphite-type carbon nitride (PCN) was prepared in an attempt to coat on the substrate. XRD patterns show the diffraction peaks of PCN are located at 13.1° and 27.1°, which can be confirm as the (100) and (002) crystal plane of graphite-type carbon nitride(C3N4). In PL analysis, the emission peak of PCN is lower than C3N4, which can be contributed to the phosphorus doping. In photodegradation reactions, 10 wt% of phosphorus-doped C3N4 (10PCN) showed the highest degradation activity under visible light irradiation among the samples. In the hollow fiber membrane system, an inorganic hollow fiber membrane was prepared by spinning using an alumina solution. SEM images revealed the pore diameter of the membrane was approximately 1.2 mm and the membrane thickness was around 200 μm. To fabricate a PMR system, PCN was integrated with PMR system for wastewater treatment under irradiation of metal halide lamp. The removal efficiency of the PMR system is 1.63 and 1.22 times higher than the batch photodegradation system and the membrane system, respectively. The PMR system show high stability and can effectively removal different kinds of organic wastewater. KEYWORDS: Photocatalytic-Membrane Reactor, phosphorus doping, graphite carbon nitride, methyl blue, visible light

碩士
朝陽科技大學
環境工程與管理系碩士班
99
In this study, anodic oxidation method was used to prepare titanium dioxide nanotube. A power supply was connected with two electrodes that immerged in fluoride solution. A titanium plate acts as anode and a platinum plate as cathode. The titanium dioxide layer grows on the titanium plate and sequentially corroded by fluoride to form nanotubes. Anodic growth of self-organized, high-aspect-ratio and highly ordered TiO2 nanotubes arrays membrane was prepared and nanotubes on the membrane were penetrated sequentially by electrochemical etching technique to remove the titanium barrier layer. The titanium plate finally forms a both-ends opened membrane. The membrane was then used as a photocatalyst for the degradation of methylene orange by photocatalytic and photoelectrocatalytic reaction. We used three methods to prepare the membranes including one-step with acid etching method, two-step with increasing voltage method, two-step with decreasing voltage method and three-step anodic oxidation method. The acid etching parameters are too critical to from a penetrated membrane. The membrane prepared by two-step methods was very brittle and can not peel off from titanium plate. The successfully penetrated membrane was prepared by three-step anodic oxidation method. The temporal varieties of degradation ratio were studied throughout two parameters including solution pH and UV light intensities. The results showed degradation ratios decrease as solution pH increase within the range from 2 to 10. The degradation ratios increase as UV light intensities increase within the range from 5 to 20mW/cm2. Furthermore, the reaction rate constant of photoelectrocatalysis is 2.25 times that of photocatalysis.

Dissertação de Mestrado Integrado em Engenharia Química apresentada à Faculdade de Ciências e Tecnologia
Os métodos convencionais utilizados nas estações de tratamento de água não são eficazes para remover contaminantes de carater emergentes, sendo que faz parte desses contaminantes um conjunto de compostos orgânicos, que são conhecidos por parabenos. Neste trabalho estudou-se um método de processos avançados de oxidação, a fotocatálise, para tratar 3 tipos mais comumente usado de parabenos que são: o metil, o etil e o propilparabeno. Nesta dissertação foi utilizado como catalisador o dióxido de titânio (TiO2) suportado em um material de base silicone o polidimetilsiloxano (PDMS). Para fixar o TiO2 na superfície polimérica utilizou-se a técnica de descarga de plasma a frio para tornar a superfície hidrofílica seguida de irradiação ultravioleta (UV) para fixar o catalisador nesta superfície. Foi primeiramente testado o efeito do tempo de exposição à radiação UV na fixação do catalisador, sendo analisados os tempos de 15, 30, 60, 90 e 120min tendo como melhor tempo os 60 min. Definida a técnica que seria usada para a fixação do catalisador, estudou-se o efeito da carga do catalisador no processo de fotodegradação, utilizando as concentrações de 70, 140, 280, 1000 e 10000mg/L. Analisando os resultados da percentagem de remoção dos parabenos através da fotocatálise com radiação solar chegou-se à conclusão de que a melhor concentração de catalisador era de 140 mg/L.Foram testados alguns fatores como a adsorção dos parabenos pela membrana, uma vez que isso poderia interferir nos resultados da fotocatálise, porém verificou-se que este processo não ocorre, tal como o processo da fotólise dos parabenos que é negligenciável. Também foi testado o dióxido de titânio não suportado de modo a analisar a eficiência do processo, tendo que o facto de imobilizar o catalisador melhora a sua aplicabilidade industrial, mas resulta numa perda de eficiência na fotodegradação. Outro parâmetro que influenciou na eficiência da fotocatálise foi o fluxo de fotões, verificando que nos dias em que esse valor era mais alto, o que ocorreu no final do Verão, a degradação foi mais eficaz, que no início do Outono. Também se utilizou uma lâmpada que emite radiação UVA que é a possivelmente a radiação mais responsável pelo processo de degradação. Os resultados obtidos com a radiação da luz solar foram melhores do que aqueles com a lâmpada uma vez que a potência UVA da lâmpada era inferior a potência que sol emite. Todos os resultados analisados na etapa da fotodegradação foram obtidos através da técnica de cromatografia líquida de alta-eficiência (HPLC). Caracterizou-se também a superfície da membrana e através das imagens do Microscópica eletrônica de varrimento (SEM) e espectroscopia de dispersão em energia (EDS), verificou-se a formação de aglomerados e também que a distribuição do catalisador na membrana não é uniforme. Ambos os fatores são prejudiciais ao processo da fotodegradação. Por último realizou-se uma análise do efeito da remoção dos parabenos no crescimento de uma bactéria Aliivibrio fischeri, de modo a analisar a toxicidade das amostras. Mostrou-se que a solução de parabenos é toxica ao longo do tempo e que o processo de degradação pode produzir produtos secundários que aumentam a taxa de inibição da bactéria.
The conventional methods used in wastewater treatment plants are not effective for removing contaminants of emerging concern, and part of these contaminants is a set of compounds, which are known as parabens. This work studied an advanced oxidation process, the photocatalysis, to treat the 3 most used types of parabens, which are: methyl, ethyl and propylparaben.In this dissertation, titanium dioxide (TiO2) supported on a silicone polydimethylsiloxane (PDMS) was used as catalyst. To fix TiO2 on the polymeric surface, the cold plasma discharge technique was used to make the surface hydrophilic followed by ultraviolet (UV) irradiation to fix the catalyst on this surface.It was firstly tested the effect of the exposure time to UV radiation for the catalyst supporting, analyzing the times of 15, 30, 60, 90 and 120 min which reveal that the best time was 60 min. Having defined the technique that would be used to fix the catalyst, the effect of the catalyst load on the photodegradation process was studied, using concentrations of 70, 140, 280, 1000 and 10000 mg/L. Analyzing the results of the percentage of removal of parabens, it was concluded that the best catalyst load was 140 mg/L.Some factors were tested, such as the adsorption of parabens on the membrane, since this could interfere with the photocatalysis results. However, it was found that this process does not occur, such as the process of photolysis of parabens that is negligible. Powdered titanium dioxide was also tested in order to analyze the efficiency of the process. In fact, catalyst immobilized improves its industrial applicability but results reveal a loss of efficiency in the photodegradation.Another parameter that influenced the efficiency of the photocatalysis is the photon flux, verifying that on the days when this value was higher, which occurred in the summer, the degradation was better, than the beginning of autumn. A lamp that emits UVA radiation was also used, which is the radiation responsible for the degradation process. The results obtained with sunlight radiation were better than those with the lamp, since the UVA power of the lamp was lower than the photon flux emitted by sunlight radiation. All the results analyzed in the photodegration stage were obtained using the high-performance liquid chromatography (HPLC) technique.The characterization of the membrane surface was made through scanning electron microscopic (SEM) and energy dispersion spectroscopy (EDS). Considering the results, the formation of agglomerates was verified and the distribution of the catalyst at the membrane is not uniform and these factors are harmful to the photodegradation process.Finally, an analysis of the effect of removing parabens on the luminescence inhibition of an Aliivibrio fischeri bacterium was carried out, to analyze the toxicity of the treated samples. It has been shown that the parabens solution is toxic over time and that the degradation process can produce side products that increase the rate of inhibition of the bacteria.

碩士
國立高雄第一科技大學
環境與安全衛生工程所
93
The main objective of this study is to develop a photocatalytic oxidation/membrane separation hybrid system to remove hydrophobic organic compounds from surfactant-containing solution. Both perchloroethylene (PCE) and benzene are selected as target compounds in the study. The investigated surfactants include anionic (Sodium dodecylbenzenesulfonate, SDBS), nonionic (Triton(R) X-100, TX-100) and cationic (Cetylpyridinium chloride, CPC) surfactants. P-25 anatase TiO2 is applied as the photocatalyst in the investigation. Several experimental parameters including solution pH levels, types and concentrations of surfactants, and illuminated time are examined for investigating their influences on photocatalytic degradation rates of PCE and benzene. In addition, influent water flux, solution pH, types and concentrations of surfactants, and different pore-size stainless steel membranes are the major experimental parameters of evaluating the performance of tested membrane for the removal of TiO2 colloids. In overview, interfered photocatalysis of benzene and PCE is observed in the presence of surfactants. The decomposition of benzene and PCE follows pseudo first order reactions. But the influence is depended on the relationships among hydrophobic organic compounds and surfactants. Different influences can be observed at different pH levels, too. In neutral condition, the influence on PCE photocatalysis by surfactants follows by the order of: anionic> nonionic> cationic surfactant. In contrast, the for benzene degradation is in order of: anionic> nonionic≧ cationic surfactant. For the operation of the investigated membrane, it is observed that higher flow rate has higher removal efficiency of TiO2 colloids. Better removal efficiency for TiO2 is detected by a finer-pore-size membrane (e.g, 0.5 μm pore size). Higher removal efficiency is also observed in neutral conditions due to lager particle size of TiO2 colloids. In acidic condition, TiO2 forms a larger particle size. The addition of SDBS deteriorates the removal of TiO2. Relatively higher removal efficiency for TiO2 is observed in acid environment for the addition of SDBS, in neutral conditions for the addition of TX-100, and in both acid and base conditions for the addition of CPC.

碩士
國立臺灣大學
化學工程學研究所
99
With the increasing demand for energy in the industrial society, using solar energy to produce hydrogen by water splitting is an alternative clean and pollution-free way to produce energy. Z-scheme system is the use of two different kinds of photocatalysts to do half-reaction of water splitting , respectively, and the use of different transmission medias to transmit electrons and holes, and finally completes the whole reaction. Previous studies in our laboratory point out that the use of pretreated Nafion membrane to separate the different reaction catalyst systems, not only to pass through ion transfer mediator by diffusion effect, but also to separate hydrogen and oxygen, and thus enhance the production. In this study, first we use sol-gel method to produce Pt/SrTiO3:Rh catalyst as hydrogen production, then put it in 10vol% methanol aqueous solution to do the test of hydrogen production activity in visible light , and hydrogen production can reach 10 µmol / gcat within 6 hours. We found that at pH 1.5 the catalytic activity is the best. Producing SrTiO3 by sol-gel method can get higher activity than using solid-state method and hydrothermal method. Secondly, we add BiVO4 as oxygen production into the twin membrane reactor, and Ce4+/Ce3+ as ion transfer mediators in the aqueous solution, and use Nafion cation exchange membrane to separate the two catalysts to do water decomposition in visible light. Besides , the membrane can separate hydrogen and oxygen. In our study we use 300W xenon lamp as the visible light source and Ce4+ pre-treated Nafion membrane to separate two sides of half-reaction. The result is that the hydrogen production can be achieved certain level, and that in line with H2/O2 = 2 stoichiometric decomposition of water. Pt/SrTiO3:Rh is prepared by Sol-gel method with light deposition method, and BiVO4 is produced by liquid phase synthesis. The use of double-membrane reactor can reduce the chance of reversing reaction of hydrogen and oxygen, therefore it enhance hydrogen production rate. Separating two sides of the catalysts can also solve the problem of competitive absorption of light. We expect to test the best reaction conditions in the presence of cerium ions in order to improve the hydrogen production performance.

碩士
國立臺北科技大學
環境工程與管理研究所
98
This study was proposed for simultaneous oxidization of naphthalenesulfonate(NS) /reduction of chromium(VI) by electron- hole pair (e－-h+) using a novel technology of N-doped TiO2 with visible light photocatalysis. To extend the absorption range of TiO2 into the visible-light region, the simple procedure for preparing nitrogen doped titanium dioxide nanocrystal (TiOxNy) by calcinating the mixture of Degussa P-25 (DP-25) TiO2 and NH4Cl at temperatures of 400 °C under airtight condition. The highest nitrogen content in TiOxNy is 19.22 at. %, occurred in the sample of TiOxNy with TiO2: NH4Cl weight ratio 1:6. Furthermore, the application of cation-exchange membrane (CEM) combining electrolysis was used to enhance the efficiency for prevention of the recombination of the electrons with the electron-hole. Therefore, the objectives of this study were to investigate: (1) the effects of N-doped TiO2 dosage, pH, and NS initial concentration; (2) the photocatalytic kinetics and mechanism of the N-doped TiO2/ Cr(VI)/ NS reaction. There were three different parameters: N-doped TiO2 dosages (0.5 - 2.0 g/L), pH (3 - 10) and NS initial concentrations (0 - 400 mg/L). In the continuous photocatalytic system combining membrane electrolysis, the Cr(VI) removal efficiency increased with decreasing system pH from 20% on average for pH 10 system to about 99% for pH 3 system with N-doped TiO2 dosage of 1.0 g/L after 10 hours. Therefore, N-TiO2 photocatalysis successfully reduced Cr(VI) to Cr(III) from synthetic textile wastewaters at pH 3 under visible-light illumination. The degradation efficiency of Cr(VI) and NS increased with increasing the amounts up to 1.0 g/L, and the efficiency decreased slightly for dosage higher than 1.0 g/L. Addition of NS concentration facilitated Cr(VI) reduction in comparison with the same system. The Cr(VI) removal rates increased as NS concentration increased because the electron/hole recombination might be reduced by electrons transfer from carboxyl group to positive holes of the valence band of the N-TiO2. This synergy effect helped the reaction by hindering the electron-shuttle mechanism that occurred in NS and Cr(VI). The decomposition of NS accompanies with the diminish of TOCs and generation of sulfate. As the pH decreased, the NS removal efficiency increased. When the pH was controlled at 3 with N-doped TiO2 dosage of 1.0 g/L for 10 hours, about 95.3 % of NS removal was achieved. The yield of sulfate was formed from the degradation of NS of nearly 100%. Meanwhile, the yield of sulfate as S increased with increased in degradation of NS as S with concentration of NS from 0 to 400 mg/L. When N-doped TiO2 dosage was 1.0 g/L, both higher KCr and KNS were obtained in continuous photocatalysis combining cationic exchange membrane electrolysis. Moreover, the degradation efficiency of Cr(VI) and NS increased with increasing the amounts up to 1.0 g/L, and the efficiency decreased slightly for dosage higher than 1.0g/L. The mineralization reaction of NS can be stoichiometrically calculated. Meanwhile, the yield of sulfate as S is consistent with the increase of degradation of NS as S for the cases examined.

Dissertação de mestrado integrado em Engenharia Civil
Os efeitos dos produtos farmacêuticos no ambiente e consequentemente nos seres vivos têm vindo a causar uma inquietação crescente quer na comunidade científica, quer nas entidades gestoras de sistemas de tratamento de águas. Tendo em conta que os mesmos são usados no tratamento e prevenção de doenças, o seu consumo e disseminação nos meios hídricos tem aumentado de forma preocupante. São constantemente desenvolvidas novas substâncias cujo ciclo de vida e efeitos no ambiente são muitas vezes ainda desconhecidos, sendo, por esse motivo, considerados como poluentes emergentes. Entre outros, os antibióticos são um dos grupos de compostos mais usados no tratamento veterinário e humano. Embora utilizados numa extensão semelhante, os fármacos veterinários, como a oxitetraciclina (OTC), não têm sido tão estudados no que respeita aos efeitos da sua emissão e presença nos ecossistemas aquáticos. Assim, na base desta dissertação estiveram presentes duas vertentes de estudo. A primeira vertente incidiu na avaliação da eficiência de degradação da OTC através da fotocatálise heterogénea, com dióxido de titânio (TiO2) e óxido de zinco (ZnO), em diferentes matrizes aquosas (água destilada e de abastecimento público) e condições de ensaio (concentração inicial do catalisador, tempo de exposição e fonte de radiação UV). A segunda vertente recaiu sobre a avaliação da permeabilidade de membranas fabricadas em laboratório, bem como a sua utilização na retenção de OTC em soluções aquosas. Nestes ensaios foram utilizadas membranas com e sem TiO2 na sua constituição, permitindo assim avaliar o efeito da presença desse fotocatalisador nesse processo de separação. Nesta dissertação foi também avaliada a toxicidade da concentração inicial do fármaco, bem como dos subprodutos resultantes da sua oxidação. A determinação das concentrações de OTC foram efetuadas com recurso à técnica laboratorial de espectrometria UV-visível. A melhor eficiência de remoção de OTC foi de 92% obtida nos ensaios de fotocatálise sob radiação da lâmpada UV, com uma concentração de 31 mg.L-1 de ZnO e para um tempo de exposição de 120 minutos. Os resultados dos ensaios de toxicidade realizados indiciam que a aplicaçao da fotocatálise com TiO2 e ZnO suspensos não induz o aparecimento de subprodutos tóxicos na água. Os valores mais satisfatórios em termos de permeabilidade hidráulica e de retenção de OTC foram obtidos com uma membrana com TiO2 na sua composição e podem considerar-se promissores.
The effects of pharmaceuticals in the environment and consequently in living beings have been causing an uneasiness growing in the scientific community and in managing bodies of water treatment systems. Given that they are used in the treatment and prevention of diseases, their consumption and dissipation in water resources has alarmingly increased. Constantly are developed new substances whose life cycle and effects on the environment are often still unknown, and, therefore, considered as emerging pollutants. Among others, antibiotics are one of the groups of compounds commonly used in veterinary and human treatment. Although used to a similar extent, veterinary drugs, such as oxytetracycline (OTC), haven’t been as studied with regard on the effects of their issue and presence in the ecosystems. So, on the basis of this dissertation were present two study sections. The first part focused on the evaluation of the OTC degradation efficiency by heterogeneous photocatalysis, with titanium dioxide (TiO2) and zinc oxide (ZnO), in different aqueous matrices (distilled water and public supply) and test conditions (initial concentration of catalyst, exposure time and UV radiation source). The second part has fallen on the evaluation of membrane permeability manufactured in laboratory as well as their use in OTC retention in aqueous solutions. The membranes used in these tests were with and without TiO2 in its composition, allowing to evaluate the effect of the presence of the photocatalyst in the separation process. On this thesis was also evaluated the toxicity of the initial drug concentration and of the by-products resulting from the oxidation. The determination of OTC concentrations were performed using the laboratory techniques of UV-visible spectroscopy. The OTC better removal efficiency of 92% was obtained in the photocatalysis tests under irradiation of UV light, at a concentration of 31 mg L-1 of ZnO and a time of 120 minutes exposure. The results of the toxicity tests indicate that the application of photocatalysis with TiO2 and ZnO suspended doesn't induce the appearance of toxic by-products in the water. The most satisfactory values in terms of hydraulic permeability and OTC retention, were obtained with a membrane with TiO2 in their composition and that can be regarded as promising.

University of Technology, Sydney. Faculty of Engineering.
Arsenic is a toxic semi-metallic element that can be fatal to human health. It can have a significant adverse impact on the environment. Arsenic pollution in water has been found in many parts of the world, especially in developing countries such as Bangladesh, India, Nepal, and Vietnam. It is also detected in some areas of Australia. In rural area of Victoria, arsenic concentrations of up to 8 μg/L and 220 μg/L in groundwater and surface water have been reported. The arsenic contamination in water forced the water and health authorities to introduce stringent standards for arsenic levels in drinking water. World Health Organization (WHO) has recommended the arsenic level in drinking water to the stricter level to be 10 μg/L instead of 50 μg/L (since 1993). The U.S. Environmental Protection Agency (EPA) has lowered the maximum contaminant level (MCL) of arsenic from 50 μg/L to 10 μg/L. Rigorous criteria of arsenic level have been enforcing water authorities to identify and put into practice suitable and cost-effective arsenic removal technologies. The main objectives of the research described in this thesis were to develop and assess the potential and effectiveness of a new adsorbent medium namely iron oxide coated sponge (IOCSp) in removing arsenite [As(III)] and arsenate [As(V)J to an acceptable level in drinking water supplies. Arsenite [As(III)] and arsenate [As(V)] are the two predominant arsenic species found in groundwater. Regeneration of the exhausted IOCSp was also investigated. In addition, two other adsorbents: iron oxide coated sand 2 (IOCS-2), and surfactant modified zeolite - zero valent iron (SMZ/ZVI) were evaluated and their efficiency were compared with that of IOCSp. Effectiveness of membrane and photocatalysis hybrid systems in removing arsenic was studied. In this study, tap water (Sydney, Australia and Regina, Saskatchewan, Canada) spiked with predetermined amounts of As(III) and As(V) was used in the batch, tray and column studies. Raw water containing arsenic from Kelliher, Saskatchewan and Van Phuc Village, Hanoi, Vietnam were also investigated in the study. The research described below investigated optimised conditions for coating iron oxide on sponge by different coating conditions. Optimum conditions for coating the sponge with iron oxide were as follow: (i) pH value of coating condition of 4 (ii) time of contact between iron oxide and the sponge during coating of 10 hours; (iii) coating temperature of 110°C; and (iv) time of drying of sponge after the coating of 20 hours. The maximum adsorption capacities of IOCSp for As(III) and As(V) estimated by Langmuir, and Sips models were up to 4.18 and 4.6 mg/g of IOCSp, respectively. More than 92.4% of both As(III) and As(V) was removed after a contact period of 9 hours with the IOCSp (based on batch studies). The IOCSp adsorption equilibrium results with synthetic water fitted reasonably well with Freundlich, Langmuir, and Sips isotherms, indicating favourable adsorption. The performance of the IOCSp column was experimentally evaluated with synthetic water spiked with arsenic. The results showed that the IOCSp column could maintain high arsenic removal efficiency even after a long filtration time without any need for regeneration. For example, a filter packed even with very small amount of 25 g IOCSp maintained a consistent arsenic removal efficiency of 95% from synthetic water containing arsenic concentration of as high as 1,000 /μg/L. This produced a throughput volume of 153 and 178 L of water containing As(III) and As(V) respectively before any need for regeneration or disposal of IOCSp. A relatively small amount of IOCSp (8 g) could treat 42 - 63 L of arsenic contaminated groundwater (56 - 156 μg/L) in Kelliher (Canada) and in Hanoi (Vietnam) to a level of less than 20 μg/L. Studies showed that As(V) removal was better compared with As(III) removal. The results showed that the performance of IOCSp was superior to than that of iron oxide coated sand (IOCS-2) and surfactant modified zeolite - zero valent iron (SMZ/ZVI) in terms of weight of media. The IOCSp, once exhausted, can be regenerated with a small amount of sodium hydroxide 0.3M. The regenerated IOCSp did not have any significant decrease in removal effectiveness as compared to the fresh IOCSp. Photooxidation experimental results also showed that photooxidation of As(III) to As(V) with titanium dioxide (Ti0₂) as photocatalyst is possible within minutes. Further, Ti0₂ can also adsorb both As(III) and As(V) on its surface. Thus, the photocatalysis reaction with Ti0₂ can reduce about 98% of arsenite from water containing 500 μg/L of arsenite. By adding nanoscale zero valent iron (nZVI) of 0.05 g/L in the photo reactor, arsenic removal can be significantly enhanced to a value less than 10 μg/L. The amount of TiO2 used in this photocatalysis hybrid system was only 20% of normal photocatalysis operation. Removal of arsenic by a membrane is highly dependent on the species of arsenic and the properties of membranes. About 57% of As(III) and 81% of As(V) removal from 500 μg/L arsenic solution could be achieved by nanofiltration (NF) of 700 molecular weight cutoff. This removal efficiency could be increased to more than 95% by an inline addition of 0.2 g/L of nZVI. This method is suitable when high quality effluent is required. In summary, the study demonstrated conclusively that iron oxide coated sponge is an excellent media for reducing arsenic. IOCSp filter can be used as an effective and economical treatment system in removing arsenic from contaminated groundwater. The merits of the IOCSp filter process are the consistent removal efficiency, long life cycle, and simplicity in operation, regeneration and disposal.