Добірка наукової літератури з теми "4004 Chemical engineering"

Abstract Nowadays, sustainable and eco-friendly products are gaining more attention in various engineering industries owing to their considerable strength-to-weight ratio, abundant availability, and recyclability. The properties of biofibers depend on the cultivation method, environmental conditions, and extraction method. Biofibers are hauled out by dew retting, water retting, and mechanical decortication methods. The properties of natural fiber–reinforced composites can be enhanced by proper physical and chemical treatments. The aim of this study is to propose a complete evaluation of the different extraction methods applied on natural fibers. Various physical and chemical treatment methods were used to ascertain the properties of optimized natural fiber-reinforced composites for various industrial applications. The key findings derived from various existing data and the chemical treatment results of the biofiber-reinforced composite are specifically highlighted with critical assessment. The properties and use of natural fiber-reinforced composites in the various fields of applications have made them candidates of choice over synthetic petroleum–based fibers.

Correction for ‘Rapid and sensitive leukemia-derived exosome quantification via nicking endonuclease-assisted target recycling’ by Mengyang Zhou et al., Anal. Methods, 2021, 13, 4001–4007, https://doi.org/10.1039/D1AY00854D.

BaTiO3 thin films were prepared on metallic foil substrates using chemical solution deposition. The impact of A to B site cation ratios on the phase assemblage and microstructural and dielectric properties was investigated by characterizing a sample set that includes stoichiometric BaTiO3 and 1, 2, 3, 4, and 5 mol% excess BaO. Each composition was subjected to a high-temperature anneal step with maximum dwell temperatures of 1000, 1100, and 1200 °C for 20 h. Excess barium concentrations greater than 3% lead to dramatic grain growth and average grain sizes exceeding 1 μm. Despite the large deviations from stoichiometry and the 20 h dwell time at temperature, x-ray diffraction, and high-resolution electron microscopy analysis were unable to detect secondary phases until films with 5% excess barium were annealed to 1200 °C. Thin films with 3% excess barium were prepared on copper substrates and annealed at 1060 °C, the practical limit for copper. This combination of BaO excess and annealing temperature produced an average lateral grain size of 0.8 μm and a room-temperature permittivity of 4000. This is in comparison to a permittivity of 1800 for stoichiometric material prepared using identical conditions. This work suggests metastable solubility of BaO in BaTiO3 that leads to enhanced grain growth and large permittivity values. This technique provides a new solid-state means of achieving grain growth in low thermal budget systems.

DNA microarrays are a potentially disruptive technology in the medical field, but their use in such settings is limited by poor reliability. Microarrays work on the principle of hybridization and can only be as reliable as this process is robust, yet little is known at the molecular level about how the surface affects the hybridization process. This work uses advanced molecular simulation techniques and an experimentally-parameterized coarse-grain model to determine the mechanism by which hybridization occurs on surfaces and to identify key factors that influence the accuracy of DNA microarrays. Comparing behavior in the bulk and on the surface showed, contrary to previous assumptions, that hybridization on surfaces is more energetically favorable than in the bulk. The results also show that hybridization proceeds through a mechanism where the untethered (target) strand often flips orientation. For evenly-lengthed strands, the surface stabilizes hybridization (compared to the bulk system) by reducing the barriers involved in the flipping event. Additional factors were also investigated, including the effects of stretching or compressing the probe strand as a model system to test the hypothesis that improving surface hybridization will improve microarray performance. The results in this regard indicate that selectivity can be increased by reducing overall sensitivity by a small degree. Another factor that was investigated was the effect of unevenly-lengthed strands. It was found that, when unevenly-lengthed strands were hybridized on a surface, the surface may destabilize hybridization compared to the bulk, but the degree of destabilization is dependent on the location of the matching sequence. Taken as a whole, the results offer an unprecedented view into the hybridization process on surfaces and provide some insights as to the poor reproducibility exhibited by microarrays. Namely, the prediction methods that are currently used to design microarrays based on duplex stability in the bulk do a poor job of estimating the stability of those duplexes in a microarray environment.

It is of great interest to develop and utilize a high surface area material with optimized hydrogen sorption properties. The need for a renewable energy source to replace automobile gasoline has become more critical in the past decade. Hydrogen is a viable fuel source for automobile usage; however, the question of how hydrogen will be safely and efficiently stored still remains. Critical factors for optimum hydrogen storage include ambient conditions and low activation temperature for adsorption and desorption phenomena. In order for optimum hydrogen adsorption to be achieved, the properties of (1) high surface area, (2) optimum hydrogen adsorption energy, and (3) Kubas interactions between metals and hydrogen molecules need to be considered. Fullerenes have recently become more popular with the discovery and mass production of graphene sheets derived from graphite. Graphene is a modified form of graphite that takes the form of sheets with less agglomeration than its respective graphitic form. This form has the potential for high surface area and storage capabilities. Storage of hydrogen at room temperature must be optimized by increasing the surface area and having an adsorption enthalpy between 15 - 20 KJ/mol. Graphene (G) sheets and graphene oxide (GO) sheets have been utilized as a matrix for hydrogen storage. These materials can also be cross-linked with organic spacers in order to form a porous framework of higher surface area. Metal decorating by calcium and platinum of the G/GO matrix has been used to enhance Kubas interactions, adsorption enthalpies, and spillover phenomenon. The use of a polymer matrix has also been implemented. Polyaniline is a novel superconducting polymer with unique electronic properties. Complexes of Polyaniline with graphene and graphene oxide have been investigated for hydrogen storage properties. Graphene and graphene oxide surface modification via metal decoration have been investigated in order to determine the most efficient synthesis and particle size on the G/GO matrix. Characterization by XRD, BET, adsorption enthalpy, PCT, TGA, FT-IR, and TEM/SEM (when applicable) were employed to optimize and compare the materials in the effort to develop a suitable storage material.

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.

The pulp and paper industry traditionally consumes high levels of water and energy and the reduction of fresh water use with emphasis on process water management and wastewater recycling are key factors for the growth of this industry. The use of fresh water has reduced significantly during the last decades. The main reasons for this include increased environmental legislations relating to effluent discharge, and hefty costs arising from either the supply of fresh water or treatment of wastewater thus effecting the marketing potentials. Although using recovered paper as raw material has an advantage of saving energy, water and landfill space, attention needs to be paid to treating the wastewater due to discharge regulations and standards. Wastewater sent to a treatment facility is regarded as waste. It is treated only with the purpose not to cause a negative impact to the environment. Although the level of impurities and toxic substances in treated wastewater satisfies the discharge standards, it often limits recycling potential because it adversely affects manufacturing processes and paper quality. Methods for removing these impurities and toxic substances include various physical and biological methods and the intended reuse of the water determines type and level of treatment required. This study aims to explore the possibility of introducing advanced technologies such as enhanced coagulation and flocculation, and membrane separation to improve wastewater recycling in a commercial paper mill. A commercial plant water circuit was first analysed and a water balance was proposed to reduce the water consumption from 10m3 to 6m3/tonne product. The quality of treated wastewaters and associated parameters from commercial individual processes were analysed to forecast the plant influent flows and predict pollutants concentrations in wastewater. Although organics in wastewater were mostly processed through biodegradation, non-biodegradable recalcitrant compounds limit its potential for reuse, thus a tertiary treatment is proposed. Enhanced coagulation and flocculation yielded very promising results, especially for colour removal. The treatment was able to achieve the target colour value. The desirable COD output values were also achieved by varying coagulation/flocculant ratio. For membrane separation, different units of operation and pollution parameters were examined. Results indicate that membrane technology produced higher colour removal efficiencies (96% for NF and 87% for UF) compared to enhanced coagulation and flocculation (61%). However, when it comes to removing COD, enhanced coagulation and flocculation was able to achieve a removal efficiency of 46% COD, compared to 43% for NF and 20% for UF. Amongst the three methods, UF, if used as a stand-alone method, failed to reduce the COD level to the target value. However, when feedwater was pre-treated with coagulant, UF was able to produce a similar COD removal rate to NF. Pre-treating feedwater also reduced fouling of membranes. Between the two membrane cleaning agents used, alkaline was shown to be more effective in reducing fouling. Backwashing was also investigated and found to be effective in prolonging membrane lifespan. However, despite the reduction in fouling, irreversible fouling still happened. Although membrane technology performed better in the removal of colour, retrofitting a membrane system into an existing plant can be difficult, requires the implementation of appropriate pre-treatment technology to control fouling resulting in higher capital and operating costs compared to enhanced coagulation and flocculation.

Synthesis of copper nanoparticles by a colloidal recipe in a two-phase liquid-liquid mixture (toluene/water) was investigated. The synthesis recipe used in this work was originally applied for the fabrication of alkylamine-capped gold nanoparticles. This method involves transferring metal cations from the aqueous layer to the organic one by the phase transfer reagent, tetraoctylammonium bromide, followed by reduction with sodium borohydride in the presence of oleylamine, which was used as the stabilising ligand. Several modifications were made to the original recipe to produce copper nanoparticles with high degrees of purity and stability. These particles are potentially applicable in various industries and are considered as an alternative for expensive metal nanoparticles, such as gold, silver, and platinum. Due to the high tendency of copper for oxidation, all of the synthesis experiments were carried out in a glove box under the flow of an inert gas (N2 or Ar). The concentration of Cl− was initially increased to form anionic complexes of copper that could later react with the cationic phase transfer reagent. This modification was followed to enhance the efficiency of the transferring step; however, the presence of anion, Cl−, at the surface of the synthesized particles was reported to change their properties; thus, increasing chloride concentration was eventually ignored. The decanting of two phases prior to the reduction step was also investigated to examine whether the site of the reduction reaction could be limited to cores of reverse micelles. The aggregated nanoparticles, which were fabricated by reducing the decanted organic phase, were heated after the synthesis at 150°C for 30 minutes to obtain a light green solution of nanoparticles. However, further characterization was not possible due to the hydrocarbon impurities. Dodecane, which was employed as the solvent for post-synthesis heating procedure, is believed to result in these impurities. Further investigation is required to explain the mechanism by which post-synthesis heating facilitates nanoparticle stabilization. Duplication of the original recipe for copper in an inert atmosphere resulted in a mixture of assembled layers of separated copper nanocrystals with an average size of ~ 5 nm and aggregated clusters of cubic copper (I) oxide nanoparticles. The possible mechanism for this division is believed to be the presence of the phase transfer reagent capped to the surface of a portion of synthesized particles leading to their metastability.

High rate algal ponds (HRAPs) can be utilised as an efficient and economical wastewater treatment method while also producing algal biomass. This study focused on the use of HRAPs to assimilate nutrients from secondary lagoon effluent and investigated various methods in which to enhance the algal biomass productivity of the HRAPs. The natural operation, productive potential, biomass production, nutrient removal capacity and environmental conditions were observed. From these findings, three experiments were proposed to enhance biomass production and in turn, the nutrient removal of the HRAPs. The first experiment was the addition of three separate algal cultures to the HRAPs during winter. Two of the algal species enhanced biomass production, however, there was no significant difference in nutrient removal during any of these experiments. The second set of experiments controlled the pH of the HRAPs utilising an inorganic and organic acid to determine if it was solely the control of pH which enhanced biomass production or if the addition of carbon that played a significant role. It was found that under high algal productivity conditions utilising inorganic acid to control pH negatively impacted algal growth whereas utilising organic acid significantly enhanced algal growth. The third experiment compared secondary lagoon effluent and primary lagoon effluent as the media sources. Secondary lagoon effluent was found to have higher biomass productivity by 106mg/L. This was thought to be a result of the primary lagoon effluents high colloidal turbidity. The results from the biomass enhancement experiments alongside the natural operation of the HRAPs were utilised to develop a simple and accurate algal growth model which utilised readily available data. The model aims to determine the biomass production of HRAPs in the south-eastern Australian climate which operated under elevated pH levels. The model was validated against the use of both secondary and primary lagoon effluent in the HRAPs and returned an R-squared value 0.98, suggesting a high accuracy. Following this work, two algal harvesting methods were investigated; membrane filtration and fungal flocculation. Three different membrane filtration systems were trialled and compared; ceramic crossflow system, polytetrafluoroethylene (PTFE) submerged system and a metal crossflow system. The PTFE membrane was found to be the most effective of the membranes tested for harvesting algae due to its low fouling tendency, low cost and relatively constant flux. The flocculation capability of fungi to flocculate algae was examined. Aspergillus oryzae was found to be the most effective fungi species trialled for monoculture flocculation with over 95% removal for all algal species tested. The fungal flocculation of mixed algal communities in wastewater samples was also investigated and removal values of 70-100% were achieved. Overall, the work conducted provides valuable information on the operation and enhancement of HRAPs. Furthermore, the simple model developed can be utilised to help identify the potential of an area for algal biomass production and the feasibility of incorporating HRAP systems into an existing wastewater treatment facility. The two harvesting techniques trialled offer new and vital insight into the often-difficult process of algal harvesting.

Pervaporation (PV), a non-porous membrane separation process, is gaining considerable attention for solvent separation in a variety of industries ranging from chemical to food and pharmaceutical to petrochemicals. The most successful application has been the dehydration of organic liquids, for which hydrophilic membranes are used. However, during pervaporation, excessive affinity of water towards hydrophilic membranes leads to undesirable swelling (water absorption) of the membrane matrix. To control swelling, often hydrophilic membranes are crosslinked to modify physicochemical (surface and bulk) properties. Since the transport of species in pervaporation is governed by sorption (affected by surface and bulk properties) and diffusion (affected by bulk properties), it is essential to study the effect of crosslinking on the surface and bulk physicochemical properties and their effects on separation performance. This thesis focuses on the effect of crosslinking on the physicochemical properties (e.g., crystallinity, hydrophilicity, surface roughness) of hydrophilic polymeric membranes and their dehydration performance alcohol-water mixtures. Poly(vinyl alcohol), PVA was used as the base polymer to prepare membranes with various morphologies such as homogeneous, blended (with Chitosan, CS) and composite (with poly(sulfone), PSf) structures. Before applying the crosslinked membranes for the PV dehydration of alcohols, the physicochemical characterization were carried out using Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), tensile testing, contact angle and swelling experiments. The crosslinked membranes showed an increase in surface hydrophobicity from the contact angle measurements as compared to the uncrosslinked membranes. AFM surface topography showed that the membrane surfaces have nodular structures and are rough at the nanometer scale and affected by the crosslinking conditions such as concentration and reaction time. Surface hydrophobicity and roughness was found to increase with increasing degree of crosslinking. DSC measurements showed an increase in melting temperature of the polymer membranes after crosslinking. For the PV dehydration of ethanol, a decrease in flux and an increase in selectivity were observed with increase in the degree of crosslinking. Effects of membrane thickness (of PVA layer) for crosslinked PVA-PSf composite membranes were studied on PV dehydration of ethanol. Total flux and selectivity were statistically analyzed as a function of the membrane thickness. In general, the outcome agrees with the solution-diffusion (S-D) theory: the total flux was found to be significantly affected by the PVA layer thickness, while the selectivity remains nearly unaffected. Using the S-D theory, the mass transfer resistance of the selective layers was calculated and found to increase with thickness. The relatively small change observed for selectivity has been related to the crosslinking of the PVA layer that increases the surface hydrophobicity of the membrane. Chitosan-Poly(vinyl alcohol), or CS-PVA, blended membranes were prepared by varying the blending ratio to control membrane crystallinity and its effect on the PV dehydration of ethylene glycol. The blended membranes were crosslinked interfacially with trimesoyl chloride (TMC)/hexane. The crystallinity of the membrane was found to decrease with increasing CS wt% in the blend. Although the crosslinked CS-PVA blend membranes showed improved mechanical strength, they became less flexible as detected in tensile testing. The resulting crosslinked CS-PVA blended membranes showed high flux and selectivity simultaneously, for 70-80wt% CS in the blend. The effect of feed flow-rate was studied to find the presence of concentration polarization for 90wt% EG in feed mixture as well. The crosslinked blend membrane with 75wt% CS showed a highest total flux of 0.46 kg/m2/h and highest selectivity of 663 when operating at 70oC with 90wt% EG in the feed mixture. Effects of crosslinking concentration and reaction time of trimesoyl chloride (TMC) were studied on poly(vinyl alcohol)-poly(sulfone) or PVA-PSf composite membranes. Results showed a consistent trend of changes in the physicochemical properties: the degree of crosslinking, crystallinity, surface roughness, hydrophilicity and swelling degree all decrease with increasing crosslinking agent (TMC) concentration and reaction time. The crosslinked membrane performance was assessed with PV dehydration of ethylene glycol-water mixtures at a range of concentrations (30 to 90wt% EG). The total flux of permeation was found to decrease, while the selectivity to increase, with increasing TMC concentration and reaction time. The decrease in flux was most prominent at low EG concentrations in the feed mixtures. A central composite rotatable design (CCRD) of response surface methodology was used to analyze PV dehydration performance of crosslinked poly(vinyl alcohol) (PVA) membranes. Regression models were developed for the flux and selectivity as a function of operating conditions such as, temperature, feed alcohol concentration, and flow-rate. Dehydration experiments were performed on two different alcohol-water systems: isopropanol-water (IPA-water) and ethanol-water (Et-water) mixtures around the azeotrope concentrations. Judged by the lack-of-fit criterion, the analysis of variance (ANOVA) showed the regression model to be adequate. The predicted flux and selectivity from the regression models were presented in 3-D surface plots over the whole ranges of operating variables. For both alcohol-water systems, quadratic effect of temperature and feed alcohol concentration showed significant (p < 0.0001) influence on the flux and selectivity. A strong interaction effect of temperature and concentration was observed on the selectivity for the Et-water system. For the dehydration of azeotropic IPA-water mixture (87.5wt% IPA), the optimized dehydration variables were found to be 50.5oC and 93.7 L/hr for temperature and flow-rate, respectively. On the other hand for azeotropic Et-water mixture (95.5wt% Et), the optimized temperature and flow-rate were found to be 57oC and 89.2 L/hr, respectively. Compared with experiments performed at optimized temperature and feed flow-rate, the predicted flux and selectivity of the azeotropic mixtures showed errors to be within 3-6 %.

The whole Tire Industry around the Globe is set on an important mission to create a greener environment wherein the used tires, scrap worn out tires & shop floor rejected tires are used back in to the system of new Tire manufacturing thereby create a Circular Economy in the Tire Industry via non-chemical Devulcanization process. The Tyromer TDP (Tyre Derived Polymer) production process uses an industrial proven extrusion technology in a patented Twin Screw Extruder and it is reliable. The process is energy efficient as it is continuous. That also gives fundamentally more consistent product quality compared to batch processes. In this extrusion process, what goes in must come out and hence the TDP production process creates no waste. The only catalyst used in the process is Super Critical Carbon dioxide. No chemical solvents or devulcanization chemicals are used and the process is Energy efficient (400 kWh/MT), Very Fast (2 minutes from crumb powder to TDP) and having High conversion rate (99+% crumb powder to TDP).

Additive manufacturing (AM) opens up the possibility of a direct build-up of components with sophisticated internal features or overhangs that are difficult to manufacture by a single conventional method. As a cost-efficient, tool-free, and digital approach to manufacturing components with complex geometries, AM of metals offers many critical benefits to various sectors such as aerospace, medical, automotive, and energy compared to conventional manufacturing processes. Direct laser fabrication (DLF) uses pre-alloyed powder mix or in-situ alloying of the elemental powders for metal additive manufacturing with excellent chemical homogeneity. It, therefore, shows great promise to enable the production of complex engineering components. This technique allows the highest build rates of the AM techniques with no restrictions on deposit size/shape and the fabrication of graded and hybrid materials by simultaneously feeding different filler materials. The advantages and disadvantages of DLF on the fabrication of compositionally complex metallic alloys are discussed in the chapter.

Monel 400 is a nickel based super alloy containing copper as the main alloying element. Its usage in the industries like marine, aerospace and chemical, makes it an attractive choice for research. It exhibits high strength and excellent corrosion resistance. It is also classified as hard to cut material because of its lower thermal conductivity, higher hardness value and ability to react with cutting tool at higher temperature. High speed micro-milling coupled with different tool coatings was used to analyze machinability of Monel. The surface finish as a result of this study contributes towards the use of this alloy in multiple applications. Key Process parameters including cutting speed, depth of cut, feed rate per tooth and multiple tool coatings were selected as input variables. Effect of these key process parameters on surface roughness was analyzed through statistical analysis of variance (ANOVA). Feed rate having confidence level of 95% was found to be most significant parameter with contribution ratio of 27.86%.

This outline is intended to provide you with a “thumb-nail” sketch of the overall elements of Process Safety Management Standards for Highly Hazardous Chemicals, 29 CFR 1910.119. This outline will introduce you to the various aspects of the standard. Paper published with permission.

Polymeric microcapsules can be fabricated by using kernel process called “micro chemical plant system”. The size of microcapsules is more uniform than those made in the conventional pathways. Spherical microcapsules are fabricated through the innovative conjunction of the well-defined amphiphilic block copolymer and stable microfluidic procedure. Crossed microchannel chemical plant are fabricated by using double deep reactive ion etch (DRIE) on 400 μm-thick silicon wafer. The width and depth of this are 100 μm, respectively. PS-b-PMMA copolymer is synthesized by atomic transfer radical polymerization (ATRP) and molecular weight and poly dispersity index (PDI) is 9837 g/mol and 1.08, respectively. With the introduction of two immiscible fluids into the microchannel, droplet flows are visualized by using a high speed CCD camera. The microcapsule was formed due to supramolecular self-assembly of copolymer in the droplet. The characteristics of the produced microcapsules were measured by SEM. A new microfilter was also introduced to separate microcapsule from the suspension fluid.

Abstract In abroad, the treatment method adopted for the wastes above is mechanical compression and storage [1–2]. In domestic, the wastes management methods could be summarized as follows according to the surface dose of the waste substance: (1) Waste filter cores with a surface dose rate greater than 2 mSv/h are fixed in a 400L steel drum with cement in the cement solidified line of nuclear auxiliary plant (NX), and one waste filter core is installed in a 400L drum [3–5]. After reconditioning, the waste volume is 0.4m3; By storing decay, the surface dose rate of some of the high dose rate level waste filter cores decreased to below 2 mSv/h, and then they were dried, super-compacted and cemented, which greatly reduced the amount of waste generated. (2) The waste filter elements with the surface dose rate below 2 mSv/h are packed into 200L steel drums and sent to the waste treatment auxiliary workshop (QS) for drying, super compaction and cement fixation. About 3∼4 waste filter elements are packed into a 400L drum. After preparation, the average waste volume of each filter core is 0.1m3. However, the treatment time of these methods is very long, the volume of waste after treatment is still relatively large, and the storage and isolation time is long. To sum up, this paper innovatively adopted high-temperature melting method to conduct glass solidification treatment on the simulated contaminated glass fiber, and by this method it forms a stable glass body with stable chemical properties. Moreover, it reduces the waste volume and directly forms a solidified body which is more convenient for treatment and disposal.

Corundo-baddeleyit material (CBM) – EUCOR – is a heat- and wear-resistant material even at extreme temperatures. This article introduces a numerical model of solidification and cooling of this material in a non-metallic mold. The model is capable of determining the total solidification time of the casting and also the place of the casting which solidifies last. Furthermore, it is possible to calculate the temperature gradient at any point and time, and also determine the local solidification time and the solidification interval of any point. The local solidification time is one of the input parameters for the cooperating model of chemical heterogeneity. This second model and its application on EUCOR samples prove that the applied method of measuring the chemical heterogeneity provides the detailed quantitative information on the material structure and makes it possible to analyze the solidification process. The analysis of this process entails statistical processing of the measurement results of the heterogeneity of the EUCOR components and performs the correlation of individual components during solidification. The verification of both numerical models was conducted on a real cast 350 × 200 × 400 mm block.

Abstract Titania (TiO2) coatings were produced using the high velocity oxy-fuel (HVOF) technique on Ti-6Al-4V substrates. The titania feedstock powder exhibited nanostructured morphology, formed by the agglomeration of individual nanostructured titania particles (spray-drying) smaller than 100 nm. The resulting coatings were dense (porosity &lt;1%) and exhibited rutile and anatase as phases with percentages of ~75% and ~25%, respectively. These coatings were heat-treated in a H2/N2 environment at 700oC for 8 h. During the heat-treatment, nanostructured titania fibers were formed on specific surface regions of the coatings. The nanofibers formed by this “chemical or reaction-based texturing” exhibited diameters of 50-400 nm and lengths in the order to 1-5 µm. It is thought that engineering these surfaces at nano and microscales may lead to interesting applications of titania coatings related to cell attachment/growth (for biomedical applications).

Increased research into the chemistry, physics and material science of hydrogen cycling compounds has led to the rapid growth of solid-phase hydrogen-storage options. The operating conditions of these new options span a wide range: system temperature can be as low as 70K or over 600K, system pressure varies from less than 100kPa to 35MPa, and heat loads can be moderate or can be measured in megawatts. While the intense focus placed on storage materials has been appropriate, there is also a need for research in engineering, specifically in containment, heat transfer, and controls. The DOE’s recently proposed engineering center of expertise underscores the growing understanding that engineering research will play a role in the success of advanced hydrogen storage systems. Engineering a hydrogen system will minimally require containment of the storage media and control of the hydrogenation and dehydrogenation processes, but an elegant system design will compensate for the storage media’s weaker aspects and capitalize on its strengths. To achieve such a complete solution, the storage tank must be designed to work with the media, the vehicle packaging, the power-plant, and the power-plant’s control system. In some cases there are synergies available that increase the efficiency of both subsystems simultaneously. In addition, system designers will need to make the hard choices needed to convert a technically feasible concept into a commercially successful product. Materials cost, assembly cost, and end of life costs will all shape the final design of a viable hydrogen storage system. Once again there is a critical role for engineering research, in this case into lower cost and higher performance engineering materials. Each form of hydrogen storage has its own, unique, challenges and opportunities for the system designer. These differing requirements stem directly from the properties of the storage media. Aside from physical containment of compressed or liquefied hydrogen, most storage media can be assigned to one of four major categories, chemical storage, metal hydrides, complex hydrides, or physisorption. Specific needs of each technology are discussed below. Physisorption systems currently operate at 77K with very fast kinetics and good gravimetric capacity; and as such, special engineering challenges center on controlling heat transfer. Excellent MLVSI is available, its cost is high and it is not readily applied to complex shape in a mass manufacture setting. Additionally, while the heat of adsorption on most physisorbents is a relatively modest 6–10kJ/mol H2, this heat must be moved up a 200K gradient. Physisorpion systems are also challenged on density. Consequently, methods for reducing the cost of producing and assembling compact, high-quality insulation, tank design to minimize heat transfer while maintaining manufacturability, improved methods of heat transfer to and from the storage media, and controls to optimize filling are areas of profitable research. It may be noted that the first two areas would also contribute to improvement of liquid hydrogen tanks. Metal hydrides are currently nearest application in the form of high pressure metal hydride tanks because of their reduced volume relative to compressed gas tanks of the same capacity and pressure. These systems typically use simple pressure controls, and have enthalpies of roughly 20kJ/mol H2 and plateau pressures of at most a few MPa. During filling, temperatures must be high enough to ensure fast kinetics, but kept low enough that the thermodynamically set plateau pressure is well below the filling pressure. To accomplish this balance the heat transfer system must handle on the order of 300kW during the 5 minute fill of a 10kg tank. These systems are also challenged on mass and the cost of the media. High value areas for research include: heat transfer inside a 35MPa rated pressure vessel, light and strong tank construction materials with reduced cost, and metals or other materials that do not embrittle in the presence of high pressure hydrogen when operated below ∼400K. The latter two topics would also have a beneficial impact on compressed gas hydrogen storage systems, the current “system to beat”. Complex hydrides frequently have high hydrogen capacity but also an enthalpy of adsorption >30kJ/mol H2, a hydrogen release temperature >370K, and in many cases multiple steps of adsorption/desorption with slow kinetics in at least one of the steps. Most complex hydrides are thermal insulators in the hydrided form. From an engineering perspective, improved methods and designs for cost effective heat transfer to the storage media in a 5 to 10MPa vessel is of significant interest, as are materials that resist embrittlement at pressures below 10MPa and temperatures below 500K. Chemical hydrides produce heat when releasing hydrogen; in some systems this can be managed with air cooling of the reactor, but in other systems that may not be possible. In general, chemical hydrides must be removed from the vehicle and regenerated off-board. They are challenged on durability and recycling energy. Engineering research of interest in these systems centers around maintaining the spent fuel in a state suitable for rapid removal while minimizing system mass, and on developing highly efficient recycling plant designs that make the most of heat from exothermic steps. While the designs of each category of storage tank will differ with the material properties, two common engineering research thrusts stand out, heat transfer and structural materials. In addition, control strategies are important to all advanced storage systems, though they will vary significantly from system to system. Chemical systems need controls primarily to match hydrogen supply to power-plant demand, including shut down. High pressure metal hydride systems will need control during filling to maintain an appropriately low plateau pressure. Complex hydrides will need control for optimal filling and release of hydrogen from materials with multi-step reactions. Even the relatively simple compressed-gas tanks require control strategies during refill. Heat transfer systems will modulate performance and directly impact cost. While issues such as thermal conductivity may not be as great as anticipated, the heat transfer system still impacts gravimetric efficiency, volumetric efficiency and cost. These are three key factors to commercial viability, so any research that improves performance or reduces cost is important. Recent work in the DOE FreedomCAR program indicates that some 14% of the system mass may be attributed to heat transfer in complex hydride systems. If this system is made to withstand 100 bar at 450K the material cost will be a meaningful portion of the total tank cost. Improvements to the basic shell and tube structures that can reduce the total mass of heat transfer equipment while maintaining good global and local temperature control are needed. Reducing the mass and cost of the materials of construction would also benefit all systems. Much has been made of the need to reduce the cost of carbon fiber in compressed tanks and new processes are being investigated. Further progress is likely to benefit any composite tank, not just compressed gas tanks. In a like fashion, all tanks have metal parts. Today those parts are made from expensive alloys, such as A286. If other structural materials could be proven suitable for tank construction there would be a direct cost benefit to all tank systems. Finally there is a need to match the system to the storage material and the power-plant. Recent work has shown there are strong effects of material properties on system performance, not only because of the material, but also because the material properties drive the tank design to be more or less efficient. Filling of a hydride tank provides an excellent example. A five minute or less fill time is desirable. Hydrogen will be supplied as a gas, perhaps at a fixed pressure and temperature. The kinetics of the hydride will dictate how fast hydrogen can be absorbed, and the thermodynamics will determine if hydrogen can be absorbed at all; both properties are temperature dependent. The temperature will depend on how fast heat is generated by absorption and how fast heat can be added or removed by the system. If the design system and material properties are not both well suited to this filling scenario the actual amount of hydrogen stored could be significantly less than the capacity of the system. Controls may play an important role as well, by altering the coolant temperature and flow, and the gas temperature and pressure, a better fill is likely. Similar strategies have already been demonstrated for compressed gas systems. Matching system capabilities to power-plant needs is also important. Supplying the demanded fuel in transients and start up are obvious requirements that both the tank system and material must be design to meet. But there are opportunities too. If the power-plant heat can be used to release hydrogen, then the efficiency of vehicle increases greatly. This efficiency comes not only from preventing hydrogen losses from supplying heat to the media, but also from the power-plant cooling that occurs. To reap this benefit, it will be important to have elegant control strategies that avoid unwanted feedback between the power-plant and the fuel system. Hydrogen fueled vehicles are making tremendous strides, as can be seen by the number and increasing market readiness of vehicles in technology validation programs. Research that improves the effectiveness and reduces the costs of heat transfer systems, tank construction materials, and control systems will play a key role in preparing advanced hydrogen storage systems to be a part of this transportation revolution.

Corundo-baddeleyit material — EUCOR — is a heat- and wear-resistant material even at extreme temperatures. This article introduces a numerical model of solidification and cooling of this material in a non-metallic mould. The model is capable of determining the total solidification time of the casting and also the place of the casting which solidifies last. Furthermore, it is possible to calculate the temperature gradient in any point and time, and also determine the local solidification time and the solidification interval of any point. The local solidification time is one of the input parameters for the cooperating model of chemical heterogeneity. This second model and its application on samples of EUCOR prove that the applied method of measurement of chemical heterogeneity provides detailed quantitative information on the material structure and makes it possible to analyse the solidification process. The analysis of this process entails statistical processing of the results of the measurements of the heterogeneity of the components of EUCOR and performs correlation of individual components during solidification. The crystallisation process seems to be very complicated, where the macro- and microscopic segregations differ significantly. The verification of both numerical models was conducted on a real cast 350 × 200 × 400 mm block.

Chemical Spray Pyrolysis (CSP) of ZnO and SnO2 is of interest for gas sensor applications. The structural properties of the deposited film can be strongly influenced by deposition conditions. In this work, two solutions consisting of Tin Chloride and Zinc Chloride was sprayed on a heated substrate, where temperature was varied from 400° C to 450° C for ZnO, and from 350° C to 500° C for SnO2. X-ray diffraction and scanning electron microscopy, indicating a non-homogenous-structured film formed at low temperature for both oxides. At 450° C, a porous structure is observed for SnO2. This structure becomes homogenous at higher temperature. It was also found that at temperatures lower than 450° C, substrate temperature has significant impact on the composition of the synthesized films.

Flexible magnetic nanocomposite fibers were produced by electrospinning method using a polymeric solution containing poly(acrylonitrile) and magnetite nanoparticles. Magnetic nanoparticles (∼10 nm) were prepared by a chemical co-precipitation of ferric and ferrous chloride salts in the presence of an ammonium hydroxide solution. The effect of magnetic particle concentrations (e.g., 0%, 1%, 5%, 10%, 20% and 30%) on nanocomposite fibers, distribution and morphology were studied using scanning electron microscopy (SEM). The experimental study indicated that the average diameters of the magnetic nanocomposite fibers were between 400 nm and 1.08 μm. The magnetic responds were also found to increase linearly with increasing percent loading of the magnetic nanoparticles. It is concluded that this study provides promising results for various applications, such as filtration and separation of micron and nanosize organic and inorganic particles, HF antenna fabrication and biomedical.

Abstract A numerical study was conducted to determine the effects of combustion condition parameters, including inlet temperature and pressure, fuel spray characteristics on NOx emissions in gas turbine combustion using the KIVA-3V code. Log-normal spray distribution was assumed for the simulation of real fuel spray distributions at injection. A simplified mechanism with 17-species and 26-step was employed for chemical reactions of Jet A in a formula of C12H23. A sector model of a typical annular combustor was used in calculations. Flow fields and temperature distributions were analyzed. A wide range of operating condition was varied with the inlet pressure from 0.1 to 2.0 MPa, inlet temperature from 400 to 900 K, and overall fuel/air ratio from 0.012 to 0.08. The results reasonably agreed with those from experimental data and Chemkin modeling, which demonstrates the applicability of KIVA-3V and the chemical mechanism to the predictions of NOx emissions. With respect to the inlet temperature, NOx productions show a trend of monotone increasing. As the inlet pressure increases, NOx emissions increase at the beginning and then decrease. The droplet mean diameter as well as injection velocity and angle were independently varied to distinguish the separate effects of variables involved. It is found that the NOx emissions decrease with the Sauter mean diameter, but increase with the injection velocity and angle of fuel sprays. It appears that KIVA-3V code can be a valuable tool for the development of low emission combustors.