Dissertations / Theses on the topic 'Competitive sorption and desorption'

Les substances per et poly-fluoroalkylées (PFAS) constituent un vaste groupe hétérogène de micropolluants émergents. Du fait de leur structure physico-chimique très stable, les PFAS sont persistantes et largement répandues dans l'environnement et posent de nombreux problèmes environnementaux. Ces dernières années, le devenir des PFAS a fait l'objet d'une attention croissante. Dans le cycle des PFAS, l'air, l'eau, le sol et les sédiments sont différents compartiments impliqués. À l'exutoire des grands bassins versants et à l’interface terre-mer, les estuaires sont considérés comme la principale voie d’entrée des PFAS vers le milieu océanique, puits ultime des PFAS. Les conditions estuariennes complexes affectent le comportement des PFAS dans les sédiments et déterminent le sort final des PFAS. Les estuaires jouent par ailleurs un rôle écologique majeur et sont soumis à une forte pression chimique, générant des risques environnementaux. Il est donc important d'étudier le devenir des PFAS dans les estuaires.Les sédiments estuariens constituent un réservoir important pour les PFAS, où la sorption et la désorption se produisent et contrôlent la distribution des PFAS. Les conditions géochimiques jouent un rôle essentiel dans ce processus. D'une part, les flux fluviaux apportent d'énormes quantités de particules en suspension qui absorbent les PFAS et se déposent finalement dans les sédiments estuariens. D'autre part, au cours des cycles de marée, les particules sont remises en suspension, transportées et remises en place, désorbant ou réabsorbant les PFAS. La distribution des PFAS entre les particules et l'eau est la clé de l'étude du devenir des PFAS dans les estuaires. Les conditions contrastées de salinité et de turbidité des estuaires peuvent influencer la distribution des PFAS entre les particules et l'eau en facilitant ou en entravant la sorption/désorption, ce qui complique l'interaction entre les sédiments et l'eau pour les PFAS. Il est donc très important de réaliser des études approfondies sur la distribution des PFAS entre les particules et l'eau dans les conditions estuariennes.Ces travaux sont divisés en deux parties : 1) détermination des cinétiques d'adsorption et de désorption des PFAS seuls ou mélange (compétition) sur un substrat modèle, la kaolinite et 2) étudier l'influence de la salinité et de la turbidité sur la distribution particules-eau des PFAS en conditions estuariennes. Ces travaux fournissent des éléments importants pour paramétrer les modèles de devenir des PFAS et estimer les bilans de masse à l'interface terre-mer<br>To understand the fate of legacy and emerging PFAS at the land-sea interface, this work focused on the interactions with estuarine sediments. More precisely, we mainly studied the influence of co-existing PFAS, salinity (S) and suspended particulate matter (SPM) on the sediment-water partitioning of PFAS. First, to investigate the effect of coexisting PFAS on their adsorption and desorption, competitive adsorption and desorption experiments were conducted using single and mixed PFAS solutions at low concentrations, using kaolinite as model sorbent. Selected PFAS include eight perfluoroalkyl carboxylates (PFCAs), two perfluoroalkyl sulfonic acids (PFSAs) and one zwitterionic PFAS (8:2 fluorotelomer sulfonamide alkylbetaine (8:2 FTAB)), which were studied in three single-solute solutions and two mixture solutions. A pseudo-second-order kinetic model was used to fit in the adsorption and desorption kinetics data correctly. Their sorption and desorption on kaolinite were quite fast, with equilibrium reached within 2h. Sorption processes appeared to be influenced by the PFAS molecular structure: sorption increased and desorption decreased with increasing fluoroalkyl chain length, characterized by the increase of log Kd. Besides, PFSAs (i.e, PFHxS and PFOS) had greater sorption and weaker desorption than PFCAs (i.e, PFHpA and PFNA) with similar fluoroalkyl chain. The zwitterionic 8:2 FTAB showed stronger sorption and smaller desorption than anions (i.e., PFOS or PFNA) with a similar fluoroalkyl chain. Sorption and desorption data obtained for single and multi-solute experiments indicated that there was no significant statistical difference between such conditions. Thus, the influence of competitive adsorption and desorption was negligible at low concentrations. To study the influence of salinity and SPM on the sorption of PFAS, we used a sediment sample collected in the fluvial sector of the Garonne-Gironde system. We performed sorption kinetics and sorption isotherms tests for the same PFAS, under 35 combination of salinity and turbidity. Based on response surface methodology (RSM) modelling approach, results indicated the sorption kinetics of PFAS onto sediment can be described by pseudo-second-order model and 24h is the equilibrium time for targeted PFAS. Besides, PFAS sorption can be well fitted by linear model and Freundlich model, the linear sorption range for PFAS studied was in the range of 0.12 to 1.31 nM (equilibrium concentration). Moreover, based on RSM modelling approach, we found that Kd varied between 0.62 and 55271 L/kg and that both S and SPM were significant factors, i.e. the Kd of PFAS was positively related to S due to salting-out effect while it was negatively related to SPM concentration. Moreover, SPM had a stronger effect than salinity (S) for PFHxA and PFHpA, whereas S was the more dominant factor for most other compounds. For PFUnDA and 8:2 FTAB, S and SPM displayed nearly equivalent weights as drivers of Kd. In addition, a negative interaction between both factors was observed, i.e. if SPM increases, the effect of S on Kd is weaker. Overall, this work provides original results to model the sorption of legacy and emerging PFAS on estuarine sediments based on RSM modelling approach. It provides a new perspective to investigate the fate of PFAS at the land-sea interface

Master of Science<br>Department of Agronomy<br>Nathan O. Nelson<br>Phosphorus (P) is an essential nutrient in crop production, but P inputs to surface waters have resulted in impairments such as eutrophication and algae blooms. Non-point sources such as agricultural fields are a main contributor of P. Kansas, being a high agricultural dependent state, has frequent fresh water body impairments. Multiple erosion and transport processes contribute to P loss. While P loss from sheet and rill erosion has been studied extensively, P loss from ephemeral gully erosion is largely unknown. The objective of this study is to understand the effects ephemeral gullies have on the transport and transformation of P. Three fields in McPherson County with well-defined ephemeral gullies were studied. Soil samples were taken in field locations that are effected by ephemeral gullies at the 0 to 2, 2 to 5, 5 to 15, and 15 to 30 cm depths. Samples were analyzed for total P, anion exchange phosphorus (AEP) (labile P), ammonium-oxalate extractable Fe, Al, and P (Fe[subscript]ox, Al[subscript]ox, P[subscript]ox), Mehlich 3 extractable Fe, Al, Ca, and P (Fe[subscript]M3, Al[subscript]M3, Ca[subscript]M3, P[subscript]M3), equilibrium phosphorus concentration at zero net sorption (EPC[subscript]0), 1:1 soil to water pH, and texture. Soil testing showed that P quantities tend to be much higher in surface soils eroded by sheet and rill erosion and lower in subsoil soil that is eroded by ephemeral gullies. The quantity of sorptive elements such as Fe and Al, were not significantly different throughout the tested area except in areas of changing soil texture. EPC[subscript]0 testing showed it was likely that P desorbs from the surface erosion of sheet and rill and is adsorbing onto the subsoil eroded from ephemeral gullies. Sediment eroded by ephemeral gullies has a P buffering capacity greater than the sediment eroded by sheet and rill, and a small quantity of ephemeral gully subsoil will have a large effect on the dissolved P concentration of runoff. Sediment, total P loss and expected dissolved P in runoff was surveyed and modeled for two of the fields. Ephemeral gullies contributed to a majority of sediment and total P loss. The addition of ephemeral gully sediment to the erosional mix of sheet and rill sediment caused the dissolved P concentration to decrease from 0.0204 to 0.0034 mg L[superscript]-1 in one field and from 0.0136 to 0.0126 mg L[superscript]-1 in another. The results of this study show that best management practices (BMPs) such as grass waterways could cause the losses of total P to decrease as much as 2 to 12 times in fields with ephemeral gullies. However, reducing ephemeral gully erosion will likely increase dissolved P concentrations up to 600% more in runoff. Therefore, BMPs need to be combined to fully control P loss from agricultural fields.

A series of twelve laboratory column experiments were conducted to determine equilibrium partitioning coefficients (K ) and kinetic rate coefficients for sorption of four hydrophobic pollutants on a low organic carbon natural soil. K 's for trichloroethene (ICE), tetrachloroethene (PCE), 1,1,1-trichloroethane (TCA), and 1,1,2,2-tetrachloroethane (PCA), were 0.17, 0.44, 0.06, and 0.05, respectively; about as expected based on empirical carbon-based partitioning equations found in the literature. Tailing of the breakthrough curves could be accounted for with a two-site non-equilibrium solute transport model. Rates were fast compared to pore water velocities normally encountered in an alluvial aquifer, but kinetic effects were observed at pore water velocities likely to be encountered during pumping, such as for site cleanup. Desorption was faster than adsorption, with forward rates of about 10⁻⁴ to 10⁻⁵ s⁻¹ and reverse rates about 10⁻³ to 10⁻⁴ s⁻¹. The two-site model indicated that slower sites constituted roughly half the total number of sites.

In natural systems, the solution concentration and hence, potential bioavailability of trace metals is primarily controlled by adsorption-desorption reactions at the mineral-water interface. While many studies have been conducted to understand the adsorption of trace metals to soil minerals, less is known about long-term adsorption/desorption processes. In this study, we examined the influence of mixing and sorption period on the desorption of lead from goethite. Lead sorption was rapid and essentially complete in 1 h, with no change in the quantity of lead adsorbed over the 6 month sorption period. Desorption of lead was slower than the adsorption reaction and was best modeled by two first order equations. At all sorption densities, the desorption of lead followed the order Short-term (24 h) > Long-term non-stirred (6 months) > Long-term stirred (6 months). However, statistical analysis indicated that these differences were not statistically significant. Furthermore, the desorption rate coefficients were very similar for all the experiments indicating that there was no significant residence time effect in this study. However, a sample from a previous study that was allowed to age 5 years and then analyzed by the desorption procedure did have statistically significant differences between the long-term (5 years) and the short-term (5 months). These results suggest that longer adsorption periods, perhaps a number of years, may be necessary to determine if residence time effects are an artifact of the experimental conditions or truly the length of the adsorption period.<br>Master of Science

A series of bench-scale experiments was carried out to determine the rate and efficiency with which benzene and p-xylene, components of gasoline, could be removed from an unsaturated soil by air stripping. Glass columns, 30 cm in length, were packed with soil and wetted to volumetric moisture contents of 10 and 18 percent. Air saturated with one of the volatile organic compounds (VOCs) was used to load the column. Clean air was used to strip the contaminant from the soil. Benzene and p-xylene concentrations in the soil water and air were reduced four orders of magnitude after a few hours (2-8) of stripping. Benzene was removed faster than p-xylene. Air flow was the rate-limiting step early in the stripping, however slow desorption from the soil became rate-limiting as the stripping progressed. As moisture content increased the rate of removal of both contaminants decreased.

Phytoremediation is a green technology that uses plants to treat contaminated soil and groundwater. During the decades, phytoremediation has been successfully applied to remediate chlorinated solvents in a variety of environmental media. Plant sorption and uptake are key processes in the phytoremediation of chlorinated solvents. Most previous research assumed that sorption and uptake to plant roots is linear and noncompetitive, neglecting the competitive effect when co-contaminants are existed. Growing evidence, however, indicates that sorption and uptake by plants are nonlinear and competitive. This research focused on the competitive sorption and uptake of trichloroethylene (TCE) by plants in the presence of other chlorinated contaminants and their effects on phytomonitoring of organic contaminant mixtures in groundwater. The competitive sorption experiment was carried out using TCE and other homogeneous chlorinated ethenes and ethanes. Chlorinated ethenes were shown to exert significantly stronger competition on the sorption of TCE than chlorinated ethanes with molecular structures appeared to be the primary reason. Concentrations of both primary and competing compounds affect the extent of competition. Individual physiochemical properties of organic compounds could be related to the competitive capacity of chlorinated ethenes, but the roles appeared secondary. Hydroponic experiment was conducted to investigate the effect of tetrachloroethylene (PCE) and 1,1,2-trichloroethane (1,1,2-TCA) on the uptake of TCE by plants. Concentrations of VOCs in stems decreased along the height in both single and bio-solute systems, TCE/PCE ratio increased along height while TCE/1,1,2-TCA ratio was roughly constant. The results indicated that sampling point as well as the presence of co-contaminants are important considerations in phytomonitoring of organic contaminant mixtures.

Master of Science<br>Department of Civil Engineering<br>Alok Bhandari<br>In the upper Midwest, subsurface tile drainage water is a major contributor of nitrate (NO[subscript]3–N) coming from fertilizers and animal manure. Movement of NO[subscript]3-N through tile drainage into streams is a major concern as it can cause eutrophication and hypoxia conditions, as in the Gulf of Mexico. Denitrifying bioreactors is one of the pollution control strategies to treat contaminated tile drainage water. These bioreactors require four conditions which are: 1) organic carbon source, 2) anaerobic conditions, 3) denitrifying bacteria and 4) influent NO[subscript]3-N. This research focuses on investigating fate of veterinary antibiotics in woodchips commonly used in in-situ reactors. Tylosin (TYL) and sulfamethazine (SMZ) are two veterinary antibiotics which are most commonly used in the United States and can be found in tile water after manure is land applied. Partition coefficients of TYL and SMZ on wood were determined by sorption experiments using fresh woodchips and woodchips from an in situ reactor. It was concluded that the woodchips were an effective means to sorb the veterinary antibiotics leached into the tile water after application of animal manure. Linear partition coefficients were calculated and phase distribution relationships were established for both the chemicals. The fresh woodchips gave inconclusive data but predictions could be made by the information determined in the experiments using woodchips from a ten year old woodchip bioreactor. Desorption was also studied and the likelihood of desorption was predicted using the Apparent Hysteresis Index. Overall, it was found that the old woodchips allowed for quick sorption of both antibiotics. It was also found that SMZ had reversible sorption on old woodchips. Thus, it was concluded that the woodchip bioreactor would not be effective for removal of veterinary antibiotics from tile drainage. More research is required for the fate of TYL and to confirm the conclusion.

Polyethylene pipes and epoxy or polyurethane linings are increasingly used in drinking water infrastructure. As a recent introduction to the water industry, there are still many unknowns about how polymers will behave in the distribution system specifically relating to sorption and desorption of chemical contaminants. This study is in response to a spill of 4-methylcyclohexane methanol (MCHM) that occurred in January 2014 contaminating the drinking water of nine counties in West Virginia. This study investigated sorption and desorption of the odorous chemical MCHM into polymer drinking water infrastructure and granular activated carbon (GAC). Experiments for sorption of non-polar toluene and polar 1-butanol were conducted as a comparison for MCHM sorption. Additionally, a brief odor analysis was done on the ability of activated carbon to remove odor from contaminated water and on leaching of MCHM from pipe material into clean water. The results show that MCHM diffusion and solubility in polyethylene pipe materials is low. Solubility in polyethylene ranged from 0.003-0.008 g/cm3 and was more similar to the polar contaminant n-butanol than the non-polar contaminant toluene. Desorption experiments indicated that MCHM sorbed to polyethylene diffused back into water at levels that produced odor. MCHM diffused very quickly into epoxy; its solubility was similar to polyethylene pipe. MCHM caused the polyurethane lining to swell and deform. Granular activated carbon effectively sorbed MCHM to below its odor threshold. The sorption properties of MCHM indicate the potential for contamination of infrastructure and the desorption indicates subsequent recontamination of drinking water.<br>Master of Science

Táto práca sa zameriava problematiku interakcie ibuprofénu s pôdnym systémom. Popísané sú jeho základné vlastnosti, správanie a faktory ovplyvňujúce toto správanie. Vo všeobecnosti najvplyvnejšími faktormi je prítomnosť pôdnej organickej hmoty v pôde a pH. Ibuprofén patrí do skupiny nesteroidných protizápalových liečiv. Patrí medzi ľahko dostupné a vysoko konzumované liečivá. Toto prispieva k jeho narastajúcemu transportu a kontaminácii životného prostredia. Jeho prítomnosť v životnom prostredí môže pôsobiť negatívne na živé organizmy. V experimentálnej časti bol preskúmaný vplyv pôdnej organickej hmoty a pH na sorpciu a desorpciu ibuprofénu. Použité boli tri pôdy získané z odlišných regiónov Českej republiky. V rámci procesu sorpcie a desorpcie boli použité koncentrácie v rozmedzí 1 až 10 mg/l. Vplyv pH na sorpciu a desorpciu bol preskúmaný použitím koncentrácie ibuprofénu 10 mg/l a Britton-Robinsonovho pufru s pH 3, 7 a 10. Detekcia ibuprofénu v jednotlivých vzorkách bola uskutočnená pomocou UV-VIS spektrometrie a kvapalinovej chromatografie s hmotnostne spektrometrickou detekciou.

Magnesium (Mg) thin films with various thicknesses ranging from 50 to 1000 nm capped with nominally 20 nm Palladium (Pd) were prepared by a thermal evaporation unit. A total of 25 glass substrates were used in each experiment. The unit had a rotatable macro shutter, rectangular in shape, rotation axes opposite to the Mg source, which allowed controlled exposure of the substrates. Thin films of 50, 100, 150, 200, 300, 400, 500, 600, 800 nm and 1000 nm were produced in a single experiment. Hydrogenation and dehydrogenation of the films were examined using a gas loading chamber which allowed in-situ resistance measurement. Samples were hydrogenated isochronally up to 453 K with a heating rate of 1.5 K/min. Samples cooled to room temperature were subjected to dehydrogenation test. The chamber was taken under vacuum (~10-2 mbar) and the sample was heated up to 453 K at a rate of 1.5 K/min. The results showed that the hydrogenation and dehydrogenation temperatures correlate with the film thickness, thinner films reacting with hydrogen at low temperatures. While 200 nm thin film hydrogenated at 420 K and desorbed it at 423 K, 50 nm thin film hydrogenated at room temperature and desorbed it at 405 K. Thicker films needed higher temperatures to react with hydrogen. It is concluded that films thinner than 200 nm react fully with hydrogen<br>while a considerable portion of the thicker films remain unreacted. Significance of this is discussed with reference to the design of hydrogen storage systems based on thin films or nanoparticles.

For this dissertation I studied phosphorus (P) sorption dynamics in the shallow groundwater of the southern Everglades. In particular, I examined how the ambient water type governs soluble reactive P (SRP) availability through adsorption/desorption reactions with the aquifer matrix. Chapter 2 investigated how P sorption dynamics of the mangrove root zone sediment are affected by high bicarbonate brackish groundwater compared to both fresh groundwater and saltwater. The results from chapter 2 show that the sediment exhibited exceptionally low sorption efficiency in the high bicarbonate brackish water, which would allow ambient water SRP concentration to be maintained at a higher level. Chapter 3 is a detailed analysis of how P sorption dynamics in two bedrock samples are affected by incremental increases in saltwater content in a freshwater-saltwater transition zone. The results of chapter 3 indicate that a sorption edge occurs at 3 mM Cl- concentration. In water exceeding this Cl- concentration, SRP would be expected to desorb from the bedrock due to a sharp decrease in sorption efficiency between the freshwater saltwater. These results suggest that SRP is active in the ion exchange front of saltwater intrusion, with a rapid increase in SRP availability expected at the leading edge of saltwater intrusion. A landward incursion of 3 mM Cl- concentration water would be expected to raise ambient SRP concentration along the affected aquifer zone, in turn increasing SRP availability in the ecosystem where the transitional waters discharge to the surface. Chapter 4 investigates the kinetics SRP release accompanying saltwater intrusion using a column of carbonate aquifer solids and alternating inflow between fresh groundwater and saltwater. The results show an immediate and high magnitude increase in SRP concentration when saltwater flows into the column. The combined results of this dissertation show that, in the southern Everglades and possibly other carbonate coastlines as well, water type strongly controls P sorption behavior of the sediment and bedrock, and may have a direct influence on the local ecology through increased P availability. A fundamental understanding of the abiotic exchange mechanisms between SRP and the aquifer solids can aid in the successful management and protection of this unique and important ecosystem.

Magnesium is considered as one of the more promising candidates for hydrogen storage, primarily because of its abundance and the high hydrogen capacity of MgH2, magnesium dihydride (7.6 wt%). Unfortunately, practical applications of MgH2 are limited by poor hydrogen sorption kinetics and high thermodynamic stability, resulting in slow charging and the need for high temperatures to release the hydrogen. Methods to improve the sorption kinetics of MgH2, through ball-milling, alloying and introducing small amounts of additives are currently under investigation. The aim of this work was to investigate the effect of different transition metal oxides, as well as other catalysts, on the hydrogen sorption kinetics, hydrogen release temperature and cycling stability of MgH2. The rate of MgH2 absorption is determined by the physisorption and dissociation of molecular hydrogen, diffusion through the hydride layer and then nucleation of the hydride. Whereas desorption is determined by nucleation of metal phase, diffusion of atomic hydrogen through the metal and hydride, and recombination to form molecular hydrogen at the surface before dissociation of the molecule form the surface. The addition of small amounts of additives (< 10 mol%) to MgH2 during milling have been shown to have a significant effect on the kinetics of absorption and desorption of hydrogen. In addition, the effect of oxygen as a component of these additives has been extensively studied. Although a surface layer of MgO is known to slow the diffusion of hydrogen into metal, niobium oxide, Nb2O5, is one of the best additives for kinetic improvement of MgH2. It has been suggested that higher valance oxides have a greater effect on the kinetics; also recent studies have indicated that the formation of magnesium-niobium ternary oxide compound may be responsible for the enhancement, however the exact mechanism by which Nb2O5 enhances the kinetics is still unclear. Various transition metal oxides have proved to be effective additives for hydrogen absorption/desorption of Mg-based hydrides e.g., Nb2O5 and TiO2. In this work organometallic additives based on transition metal oxides (Ti and V) and halides have been chosen, some of which are liquid at room temperature. These additives were chosen to extend the oxide valency to higher values, provide a comparison between liquid and solid oxide additives, and compare a non-oxide transition metal additive (Ti-based chloride). Nb2O5 was used as the benchmark for comparisons. A range of different amounts of transition metal (Ti and V) oxides and other additives, both liquid and solid, were ball milled with pre-milled MgH2 under different gas environments and the hydrogen sorption behaviour of the ball milled composite samples was investigated using a TPD/TDS Sieverts apparatus. A key difference from previous work in this area was the use of organo-metallic compounds, some of which were liquid at room temperature. Samples were characterized using X-Ray Diffraction, and, where feasible, Scanning Electron Microscopy and Raman Spectroscopy before and after recording the hydrogen sorption behaviour. A Sievert apparatus was improved, then modified to include TPD and TDS capability to determine the hydrogen uptake and release and to perform all these measurements in one consistent environment. With the aim of understanding what effect the ball milling gas environment might have on the MgH2 sorption kinetics, two different gases, Ar and H2, were used. MgH2, with and without additives (C60, TTIP (Titanium TetraIsoPropoxide) and Nb2O5) were milled under the two different gases. In most cases the milling gas had little to no effect on desorption kinetics, but a noticeable effect in the absorption uptake was observed - by up to 2 wt% - depending on the gas used. To understand the role of an organo-metallic oxide liquid additive on MgH2 sorption kinetics, a systematic survey was performed by milling up to 2 mol% of TTIP with MgH2 and the results compared to composite samples with Nb2O5 as the additive. TTIP was found to be equally as effective as Nb2O5 with superior hydrogen capacity, and, just as for Nb2O5, only a small amount of additive, 0.5 mol% of TTIP was found to be sufficient for kinetics enhancement. Interestingly, 0.5 mol% TTIP hand-mixed with the pre-milled MgH2 was also found to be effective for desorption, but not for the absorption kinetics. To further investigate the effect of organo-metallic liquid oxides, particularly transition metal oxides, on the enhancement of the sorption kinetics of MgH2, a range of liquid oxides (Ti-based and V-based oxides) were milled with MgH2 and compared to powder oxides. Ti-based oxides were found to have superior desorption enhancement, with the liquids performing better than the powders. The V-based oxides (all liquids) showed faster absorption and higher uptake when compared to Ti-based oxides. The Ti-chloride based organo-metallic additive was investigated to compare a non-oxide transition metal additive to the oxide additives. It was found that a small amount of 1 mol% of additive milled for short time (1 h) had the best desorption of all the additives investigated in this work - but with quite poor absorption. Overall, this project established that the use of transition metal oxides as additives has a great impact on improving the sorption kinetics of MgH2. The TTIP additive produced results at least as good as the benchmark additive Nb2O5, but with the significant advantage of being able to be mixed with MgH2 without ball-milling. The Ti and V based oxides additives were also shown to be effective, Ti-based achieving better desorption enhancement, whereas V-based oxide samples had faster absorption and higher uptake. It was also determined the ball milling gas environment can have a significant effect on the sorption kinetics, but the effect depended on the additive. The difference in the effect of additives on desorption and absorption cycles confirms the need to study combinations of additives for optimal overall benefit.<br>Thesis (PhD Doctorate)<br>Doctor of Philosophy (PhD)<br>School of Environment and Sc<br>Science, Environment, Engineering and Technology<br>Full Text

Per- and polyfluoroalkyl substances (PFASs) have become contaminants of increasing concern to society due to the contamination of drinking water and the ecosystem. A better understanding of the sorption and transport of PFASs in soil systems is urgently needed, however there have been few studies dedicated to investigating competitive sorption among PFASs, and there is no available model to model such effects. This study investigated the sorption behaviour of PFASs of different carbon chain lengths and different functional groups to investigate potential competitive sorption effects. A multi-compound sorption model was set up based on Langmuir single sorption isotherms. By modelling the different PFASs both separately and mixed together in bi-solute and multi-solute systems, the possibility of modelling competition effects between different PFASs for sorption sites was investigated. The model could describe the general tendency of longer chained PFASs to outcompete shorter chained PFASs, and that perfluorinated sulfonic acids (PFSAs) outcompete perfluorinated carboxylic aids (PFCAs). However, the model failed to reproduce multi-solute sorption results for PFOS at concentrations near or above the critical micelle concentration (CMC), indicating micelle formation and multilayer sorption, which cannot be described by a Langmuir isotherm-based model. The study showed that it is possible to model competitive effects among some PFASs using this approach, although more advanced models may be needed to model the sorption of long-chained PFASs where micelle formation may occur, which would require further research to derive values for the parameters necessary to perform this type of modelling.<br>Per- och polyfluorerade alkylsubstanser (PFAS) är kolväten där alla (per-) eller vissa (poly-) avväteatomerna bytts ut mot fluoratomer. PFAS är syntetiska kemikalier som började produceras på 1950-talet och kan beså av olika långa kolkedjor och funktionella grupper vilket påverkar deras egenskaper.Den funktionella gruppen är det hydrofila (vattenälskande) ”huvudet” på molekylen vilken kan bestå avolika kemiska grupper, av vilka de två vanligast studerade grupperna är sulfonsyror (PFSA) ochkarboxylsyror (PFCA), men det finns även många andra grupper. PFAS delas också in i långa och kortaföreningar där långa PFAS har en kolkedja som är längre än 6 kol och korta PFAS har 6 kol eller färrei sin kolkedja. Den molekylära strukturen med ett hydrofilt huvud och en hydrofob (vattenhatande)fluorerad kolkedja gör att PFAS ofta används som ytaktiva ämnen. Det finns fler än 4 700 PFAS och deanvänds i många olika produkter så som vatten- och fettavstötande tyger, mattor, rengöringsmedel, plastoch non-stickbeläggningar i t.ex. stekpannor. På grund av PFAS unika egenskaper har de också använtsi brandskum där de bildar en tunn film av vatten mellan skummet och det brinnande bränslet vilketeffektivt släcker branden. Men användningen av PFAS i brandskum har visat sig särskilt problematisktdå det innebär ett direkt utsläpp av stora mängder PFAS i naturen. Kol-fluorbindningen är väldigt stark och organismer klarar inte av att bryta bindningen vilket gör attPFAS inte bryts ned utan ansamlas i naturen. Detta tillsammans med deras vattenlöslighet resulterar imånga fall i stora föroreningsplymer i grundvattnet. Livsmedelsverket har rapporterat att dricksvattnetför mer än 3,6 miljoner människor är påverkat av PFAS föroreningar i Sverige. PFAS misstänks hacancerogena och hormonstörande effekter och flera PFAS föroreningar är nu reglerade inom EU. Menäven om nya utsläpp är reglerade behöver de PFAS som redan finns i naturen åtgärdas. Det finns mångatekniker för att åtgärda PFAS-förorenade områden där man utnyttjar molekylernas förmåga att binda tillfast material (sorption). Hur starkt molekylerna binder till materialet beror på en rad faktorer så somkolkedjans längd, mängden organiskt material i vattnet och/eller materialet PFAS ska binda till,elektrostatiska interaktioner med andra närvarande joner i vattnet samt vattnets pH. I den här studien utnyttjas dessa egenskaper för att se hur effektivt olika PFAS binder till olikamaterial med hjälp av matematiska modeller. Även potentiella konkurrenseffekter undersöks då olikaPFAS binder olika starkt. Om det då finns ett begränsat antal platser för molekylerna att binda till kanen del PFAS konkurreras ut av andra PFAS som binder starkare. Det påverkar hur effektiv enåtgärdsmetod är för att rena vattnet. Studien visade att det till viss del är möjligt att modellera tävlingseffekter mellan olika PFAS, därPFAS med längre kolkedjor konkurrerar ut kortare PFAS, och PFSA är mer konkurrenskraftiga jämförtmed PFCA. Men mer avancerade modeller krävs för modellering av längre PFAS vid högrekoncentrationer då deras förmåga att bilda aggregat/miceller försvårar modelleringen. Fler studierbehövs därför för att öka mängden information som krävs för att använda dessa mer avancerademodeller.

The work presented in this thesis is divided into two parts. The first part is the sorption of Ni and Eu to granitic materials, and cation exchange capacity measurements for powdered and intact samples. The second part is method development on autoradiography. In the first part, static batch sorption experiments were carried out to study the relative sorption properties of different granitic rocks and minerals. Experimental data were described using non-electrostatic correction models such as the Langmuir, Freundlich and Linear models. Sorption data obtained for sorption in a constant pH environment and variable metal concentration were used to test the Component Additive Model (CAM). Sorption test studies carried out using energy dispersive X-ray microanalysis were used to map the sorption of Eu on an intact sample. The results showed the CAM was applicable for Ni sorption to BG but that it was not applicable for Eu sorption to any of the granitic rocks studied. The sorption data fitted the CAM in the following order; BG (1) > GA (0.7) > RG (0.5) > GG (0.2), GrG (0.2) for Ni sorption and RG (0.7) > BG (0.4) > GA (0.2), GG (0.2), GrG (0.2) for Eu sorption to the different granitic rocks. Values in brackets represent the ratio of Rd-predicted/Rd-calculated. Results from the application of the CAM showed it was not possible to predict the Rd of the bulk sample from the component minerals. Desorption studies at constant pH were analysed by calculating the hysteresis H. The results showed that the higher the Rd the higher the hysteresis. Surface complexation using JChess Geochemical Code was used to obtain surface complexation parameters for the metal-solid complex for sorption in variable pH and constant metal concentration. Experimental data were described by the mass action law to obtained proton stoichiometry at which the sorption edge is defined. Results showed the presence of NaCl decreased the sorption of Ni, and increased the sorption of Eu. Sorption kinetics experiments in different carbonate complexing environments were carried out to study the effect of carbonate on Eu sorption capacity and rate of sorption. Data were fitted to first and second order kinetic models to investigate the sorption rates. Results showed the sorption to be fast initially before reaching a steady state after more than 200 hours of equilibration. Kinetic data confirmed the low sorption capacity observed for quartz. Data obtained for sorption in a mixed radionuclide system were modelled using the Linear model and the surface complexation model. The surface complexation constants are correlated to the Rd values obtained from the linear sorption isotherms. Modelling the results using Rdmix and Rdsing showed that sorption was suppressed in a mixed system, with no effect observed for sorption to feldspar in single and mixed systems. Cation exchange capacity (CEC) measurements were undertaken to deduce a correlation between the CEC of powdered rock samples and intact sample using rock beakers developed from the British Geological Survey by applying the Bascomb method in which the pH was buffered to pH 8.1. Normalising the results using the surface area showed that the CEC of the rock beakers was 6 orders of magnitude greater than that of the powdered sample. In the second part, a method for differentiating two or more radionuclides using storage phosphor imaging plates coupled with the Storm Scanner system was tested. Initial results showed that it is possible to differentiate one radionuclide from another in a mixed system using different levels of shielding.

Dans le contexte des futurs stockages des matières nucléaires en couches géologiques profondes, le transfert desélénium 79 des eaux de nappes vers la biosphère, par le biais de l'irrigation, est un des scenarii envisagés parl'ANDRA. Le sol servirait alors d'interface entre la géosphère et la biosphère.Le modèle actuellement utilisé pour évaluer la mobilité de nombreux éléments dans le sol repose sur une représentationsimple de leur distribution entre la quantité adsorbée sur le sol et la quantité restante en solution (modèleKd), considérée comme instantanée, réversible et linéaire avec la concentration de contamination. Ce modèleprésente des lacunes vis-à-vis du sélénium puisque ce dernier peut être présent sous différents états redoxqui contrôlent sa mobilité et dont les cinétiques de transformation entre ces états sont peu connues (Se(-II), Se(0),Se(IV) et Se(VI)).Dans le but d'améliorer les prédictions faites sur la mobilité du sélénium dans un sol, le séléniate (Se(VI)), qui estla forme la plus mobile, a été utilisé pour étudier ses interactions vis-à-vis de deux sols différents (sol B et sol R).Un modèle cinétique, alternatif au modèle Kd, a été développé pour décrire l'évolution des stocks de Se(VI) ensolution, en considérant une fraction de sélénium associée au sol de façon réversible (potentiellement mobile) etune fraction stabilisée sur le sol (fixée pseudo-irréversiblement). Ce modèle intègre des cinétiques de stabilisationbiotique et abiotique sur le sol, et une cinétique de réduction en solution.Afin d'acquérir les paramètres des modèles, des expériences en batchs et en réacteurs à flux ouvert avecl'utilisation de sacs à dialyse ont été réalisées. L'acquisition des paramètres a permis de confronter les modèlescinétiques et Kd dans différents scenarii réalistes de contamination (chronique ou séquentielle) d'un sol de surfacepar du 79Se(VI).De plus, les mécanismes de sorption du Se(VI) au sein des deux sols ont été évalués en batch avec l'ajout de compétiteursspécifiques vis-à-vis de certains sites pouvant sorber ce dernier (acides humiques et carbonates de calcium).Ceci a été complété avec l'étude de la sorption du Se(VI) sur des phases pures commerciales (silice, hydroxyded'aluminium, goethite, bentonite, carbonate de calcium et acides humiques) ou extraites d'un sol (substanceshumiques), pour différentes concentrations en Se(VI) (10-8, 10-6 et/ou 10-3 mol/L), de l'impact de l'ajout dephases pures réactives, dans les sols, sur la sorption du Se(VI).Il a été montré que le Se(VI) était sorbé sous la forme de complexes de sphères externes (CSE) au sein du sol Rpour des concentrations inférieures à 10-6 mol/L, tandis que dans le sol B, la majorité était sorbée sous la formesde complexes de sphère internes (CSI). La formation de CSE étant réversible et instantanée, l'utilisation du modèleKd était donc suffisante pour décrire la sorption du Se(VI) au sein du sol R, dans les expériences en réacteursà flux ouvert.A contrario, pour le sol B, il a été montré que le modèle Kd, contrairement au modèle cinétique, présentait deslacunes pour décrire la sorption pseudo-irréversible du Se(VI), engendrée par la formation de CSI.Il a été montré que les mécanismes biotiques étaient majoritaires au sein du sol B, en raison de l'apport de nutrimentspour les microorganismes, par l'utilisation de sacs à dialyse en cellulose régénérée. Cependant les mécanismesabiotiques ont aussi eu lieux au sein du sol B.14/256Les études sur les phases pures ont montré que seuls l'hydroxyde d'aluminium (pH 5,2 et 8) et la goethite (pH 5,2)pouvaient sorber le Se(VI) respectivement de manière pseudo-irréversible et réversible (pour [Se(VI)] < 10-6mol/L).Enfin, il a été montré que l'ajout de certaines phases pures (goethite et hydroxyde d'aluminium) au sein des deuxsols, pouvait entrainer une augmentation ou une diminution de la sorption du Se(VI) par rapport à celle attendue(additivité réactionnelle). Les interactions solide/solide directes et/ou indirectes, (la plus connue étant le coating)peuvent être à l'origine de la difficulté d'évaluation, de manière générique, de la sorption du Se(VI) au sein dusol, connaissant seulement sa composition élémentaire.

Herbicidas aplicados nos sistemas de cana-de-açúcar, diretamente no solo ou sobre palha, ficam disponíveis a fenômenos de transporte, retenção e transformação. Nesse contexto, o objetivo desse trabalho foiavaliar a lixiviação e sorção de herbicidas residuais em solos com diferentes características físicoquímicas e em palha de cana-de-açúcar. Para tal, foram realizados quatro experimentos. O primeiro relativo à lixiviação, através da metodologia de bioensaios, seguindo o esquema fatorial 8 x 2 x 2, em delineamento inteiramente casualizado, com quatro repetições, sendo oito profundidades do perfil do solo, dois períodos de seca (0 e 30 dias após a aplicação dos tratamentos - DAT) e duas quantidades de palha, esse fatorial foi adotado de forma individual para os herbicidas amicarbazone (1225 g i.a. ha-1 ); imazapic (147 g i.a ha- 1 ), sulfentrazone (800 g i.a ha-1 ) e tebuthiuron (900 g i.a ha-1 ). Os herbicidas foram aplicados no topo de colunas de solo montadas em tubos de PVC com 0 e 10 t ha-1 de palha, esses tratamentos foram submetidos aos três diferentes períodos de seca (0 e 30 DATs), ao final dessas épocas foi realizada uma simulação de chuva de 30 mm e realizada a semeadura de Cucumis sativus (planta bioindicadora), as avaliações de fitoxicidade foram efetuadas aos 7, 10 e 15 dias após a emergencia - DAE, aos 15 DAE foramrealizadas as avaliações de massa seca e altura da parte aérea das plantas. O segundo experimento consistiu na determinação de coeficientes de adsorção e dessorção (Kd e Koc) em 15 solos com diferentes características físico-químicas, para os herbicidas indaziflam, imazapic e amicarbazone. Foi utilizada a metodologia de herbicidas rádio marcados com C14, aplicou-se cinco diferentes concentrações dos herbicidas frios (0,125, 0,25, 0,50, 0,75 e 1,00 ppm), associados aos diferentes solos e herbicidas rádio marcados nas concentrações de 0,24 KBq de indaziflam, 0,26 KBq de imazapic ou 0,20 KBq de amicarbazone, de forma individual em cada unidade experimental. A concentração dos herbicidas rádio marcados presentes no sobrenadante foi determinada por espectroscopia de cintilação líquida (LSS) e por diferença entre a quantidade inicialmente aplicada e a presente na solução do solo, determinando-se adsorção. Através do mesmo processo também foi avaliada a dessorção dos herbicidas em quatro dias de análise. O terceiro experimento avaliou a adsorção de indaziflam, imazapic e amicarbazone em palha de cana-de-açúcar. Um estudo típico e equilíbrio em lotes foi conduzido para determinar adsorção e dessorção em diferentes concentrações dos herbicidas. A palha de cana-de-açúcar (0,27 g) foi combinada com três concentrações dos herbicidas (0,125, 0,5 e 1 ppm) mais os herbicidas radiomarcados nas seguintes quantidades: 0,24 KBq de indaziflam, 0,26 KBq imazapic e 0,20 KBq de amicarbazone. Após o estabelecimento do equilíbrio que foi de 24 horas para os três herbicidas, foi determinada a quantidade de herbicida adsorvida na palha de cana-de-açucar. Após a analise da adsorção, a solução presente nas unidades experimentais foi descartada e reposta por uma solução de cloreto de cálcio, e a dessorção foi então analisada após 24 horas, durante o período de um dia para amicarbazone, cinco dias para indaziflam, e não foi realizada analise de dessorção para o herbicida imazapic.Um quarto experimento, abordou a intercepção de herbicidas pela palha de cana-de-açúcar mediante a simulação de chuvas em diferentes precipitações (3, 6, 12 e 24 mm). Os herbicidas foram aplicados em duas quantidades de palha de cana-de-açúcar, as quais foram espalhadas de forma uniforme sobre uma tela de aço inoxidável (5 t ha-1 e 10 t ha-1), em seguida, essa tela foi colocada sobre um recipiente de vidro. As simulações de chuva ocorreram aos 0 horas, 24 horas e sete dias após a aplicação dos tratamentos. Para o herbicida amicarbazone aos 0 DAT sem palha, a lixiviação do herbicida amicarbazone foi notada ate os 25 cm, sendo os efeitos fitotoxicos mais expressivos observados nos primeiros 15 cm, já nas aplicações de 30 DAT, nos tratamentos com palha e sem palha a lixiviação foi notada até os 10 cm, com maior fitotoxicidade nos primeiros 5 cm. Na lixiviação tebuthiuron e imazapic e sulfentrazone a permanência do produto sobre a palha de cana-de-açúcar durante 30 DAT tornou a lixiviação desses herbicidas menor. Para o herbicida sulfentrazone a presença de palha imapctou de maneira mais expressiva na lixiviação desse herbicida que o perido de seca. Para imazapic e amicarbazone, os valores de Kd foram baixos devido à sua alta solubilidade em água; no entanto, a adsorção de imazapic foi fortemente influenciada pelo pH do solo, e para amicarbazone a adsorção e dessorção foi influenciada pela matéria orgânica e pH dos solos. Para indaziflam, Kd foi correlacionado negativamente com o teor de argila, mas foi positivamente correlacionado com a matéria orgânica. A adsorção de indaziflam foi superior a 80% em todas as concentrações, enquanto que a adsorção imazapic foi inferior a 7% em todas as concentrações. A adsorção de amicarbazone foi inferior a 20% em todas as concentrações. A dessorção de indaziflam foi de 30%, 28,5% e 27,5% a 0,125, 0,5 e 1 ppm, respectivamente, após 5 dias. A dessorção máxima para amicarbazone foi observada a 1 ppm com 11%. Para o indaziflam, após um período de sete dias após a aplicação dos herbicidas sobre a palha de cana-de-açúcar simulou-se uma precipitação de 24 mm resultando na remoção de apenas 25% do herbicida interceptado. Para o herbicida imazapic a palha de cana-de-açúcar não apresentou uma barreira de expressiva para interceptação desse produto. Dessa forma, as características dos herbicidas, como a solubilidade em água e Kow, podem ser utilizadas para determinar a sua dinâmica em sistemas de produção de cana-de-açúcar, sendo que os atributos lixiviação, sorção em palha e em solo, podem direcionar a uma predileção do comportamento agronômico e destino ambiental de herbicidas residuais. Dessa forma, pode-se concluir que a presença de palha na superfície do solo atrelada aos diferentes períodos de seca pode afetar a mobilidade desses herbicidas no ambiente. Conclui-se que as cracteristicas físico-quimicas dos herbicidas associadas com os atributos do solo podem direcionar a dinâmica de adsorção e dessorção dos herbicidas. As características dos herbicidas, como a solubilidade em água e Kow, podem ser utilizadas para determinar a dificuldade de remoção dos herbicidas em palha de cana-de-açucar.<br>Herbicides applied to sugar cane systems, directly on the soils our by residues, are available to transport, retention and transformation phenomenon. In this context, the objective of this work was to evaluate the leaching and sorption of residual herbicides in soils with different physicochemical characteristics and in sugarcane residues. Four experiments were carried out. The first, was based on the bioassay methodology, followed the 8 x 2 x 2 factorial scheme, in a completely randomized design, with four replications, eight depths of the soil profile, two dry periods (0 and 30 days after application of the treatments (DAT) and two quantities of residues, this factorial was adopted individually for the herbicides amicarbazone (1225 g ia ha-1); imazapic (147 g i.a ha-1), sulfentrazone (800 g i.a ha-1) and tebuthiuron (900 g i.a ha-1). The herbicides were applied to the top of soil columns mounted in PVC tubes with 0 and 10 t ha-1 of straw, these treatments were submitted to the three different periods of dry (0 and 30 DATs), at the end of those times a 30 mm rainfall simulation and Cucumis sativus sowing (bioindicator plant), phytotoxicity (7, 10 and 15 DAE), dry mass and shoot height were evaluated. It was noted that the greatest phytotoxicity of the herbicide amicarbazone was in the 0-5 cm layer. And that periods of drought and straw decreased the mobility of this herbicide in the columns. In leaching tebuthiuron, imazapic and sulfentrazone the permanence of the product on the sugarcane straw during 30 DAT made the leaching of this herbicide minor. Thus, it can be concluded that the presence of straw on the soil surface coupled to the different periods of drought can affect the mobility of these herbicides in the environment. The second experiment consisted in the determination of coeficivity of adosorption and desorption (Kd and Koc) in 16 soils with different physicochemical characteristics, for the herbicides indaziflam, imazapic and amicarbazone. The C14- labeled radio-herbicide methodology was used to apply five different concentrations of the cold herbicides (0.125, 0.25, 0.50, 0.75 and 1.00 ppm), associated with the different soils and herbicides radio -marked at the concentrations of 0.24 KBq of indaziflam, 0.26 KBq of imazapic or 0.20 KBq of amicarbazone, individually in each experimental unit. The concentration of radiolabelled herbicides present in the supernatant was determined by liquid scintillation spectroscopy (LSS) and by difference between the amount initially applied and the present in the soil solution, determining adsorption. Through the same process the herbicide desorption was also evaluated in four days of analysis For imazapic and amicarbazone, Kd values were low due to their high solubility in water; however, the adsorption of imazapic was strongly influenced by the pH of the soil, and for amicarbazone the adsorption and desorption was influenced by the organic matter and pH of the soils. For indaziflam, Kd was negatively correlated with clay content but was positively correlated with organic matter. The third experiment evaluated the adsorption of indaziflam, imazapic and amicarbazone in sugarcane straw. A typical study and batch equilibrium was conducted to determine adsorption and desorption at different concentrations of the herbicides. Sugarcane residues (0.27 g) was combined with three concentrations of the herbicides (0.125, 0.5 and 1 ppm) plus 0.24 KBq of indaziflam, 0.26 KBq imazapic or 0.20 KBq of labeled amicarbazone radio. The adsorption of indaziflam, imazapic and amicarbazone was evaluated 24, 48 and 120 hours, respectively, after the contact of sugarcane residues. Indaziflam adsorption was greater than 80% at all concentrations, while imazapic adsorption was below 7% at all concentrations. The adsorption of amicarbazone was less than 20% at all concentrations. Indaziflam desorption was 30%, 28.5% and 27.5% at 0.125, 0.5 and 1 ppm, respectively, after 5 days. Maximum desorption for amicarbazone was observed at 1 ppm with 11%. The desorption for imazapic was not determined due to the low initial adsorption. A fourth experiment, addressed the interception of herbicides by sugarcane straw through simulated rainfall in various amounts of precipitation (3, 6, 12 and 24 mm). Two amounts of sugarcane straw were uniformly spread over a stainless steel screen (5 t ha-1 and 10 t ha-1), then the screen was placed on a Pyrex&reg; pan. The rain simulations occurred at 0 hr, 24 hrs and seven days after the treatments were applied. For indaziflam, a period of seven days after application of the herbicides on the sugarcane straw was simulated a precipitation of 24 mm resulting in the removal of only 25% of the adsorbed herbicide. For the herbicide imazapic the sugarcane straw did not present an expressive barrier to interception of this product. Thus, the characteristics of the herbicides, such as water solubility and Kow, can be used to determine their dynamics in sugarcane production systems, and the leaching, straw sorption and soil attributes can a predilection for agronomic behavior and environmental fate of residual herbicides.

The potential of utilizing a new form of chemical processing technology called SpinChem® Rotating Bed Reactor (RBR), in combination with different reactive materials, for the purpose of remediating multi-contaminated aquifers under changing environmental conditions, was investigated using laboratory studies and geochemical models. Four different reactive materials, or combinations thereof, were tested: heat-treated peat powder combined with zero-valent iron (ZVI); IronPeat, which consists of peat powder coated with a ferriferous hydrosol (FFH); and a powdered steel waste product. Results showed that the powdered steel waste was compatible with the technology while the peat-based sorbents were not. However, there were no indications that the kinetics of the sorption reactions increased. This was attributed to the fact that the rate-limiting steps, for the binding of the studied metal(loid)s onto iron oxide, are generally considered to be dependent on the later stages of the sorption process related to diffusion mechanisms and not to the rate of mass transfer through the bulk liquid phase, which is what primarily is increased through application of the SpinChem® RBR technology.

A distinção de doses dos herbicidas residuais encontradas nas recomendações oficiais para a agricultura está normalmente baseada nas classes texturais dos solos (arenosa, média e argilosa), que são distinguidas pelos teores de argila na camada superficial de solo. No entanto, a disponibilidade dos herbicidas residuais na solução do solo é função do processo de sorção, que é determinado principalmente pelas variações percentuais dos atributos do solo: teor de argila, matéria orgânica e capacidade de troca catiônica (CTC). Portanto, a recomendação de doses dos herbicidas residuais pelas classes texturais do solo pode não ser adequada. Sendo assim, foi desenvolvida a presente pesquisa com o objetivo de avaliar o comportamento sortivo dos herbicidas residuais diuron e hexazinone em função de atributos de quatro tipos de solos de texturas contrastantes, e assim verificar a correlação destes atributos com a disponibilidade dos herbicidas para as plantas. As amostras de solo foram coletadas em quatro áreas de produção de cana-de-açúcar do Estado de São Paulo, e apresentaram variações consideráveis no conteúdo de argila (6 a 67%), areia (22 a 93%), capacidade de troca catiônica (CTC) (58,7 a 152,8 mmolc dm-3) e carbono orgânico (C.O.) (13,95 a 19,19 g.kg-1). Foi utilizado o método batch com herbicida radiomarcado (14C), utilizando-se 2,0 g de solo para o herbicida diuron e 4,0 g para o herbicida hexazinone, e como substância extratora dos herbicidas o CaCl2 em volume de 8,0 mL. Cinco concentrações de cada herbicida foram utilizadas, sendo para o diuron: 0,19; 0,42; 0,84; 1,68 e 3,34 mg.L-1 e para o hexazinone: 0,12; 0,22; 0,66; 2,17 e 6,03 mg.L-1. Os resultados permitiram concluir que o solo arenoso estudado apresentou baixa capacidade de adsorção e intensa dessorção de diuron, no entanto para os solos argilosos o processo de sorção e retenção de diuron foi intenso. Houve uma correlação positiva entre a sorção de diuron com os teores de matéria orgânica e argila. Os valores de Kd para o diuron foram maiores nos solos com maior teor de C.O. (g kg-1) e argila (%); sendo que de maneira geral, a sorção do diuron foi mais relacionada com o teor de C.O. do solo, que com a argila. Os valores de Kd, Koc e Kf(sor) do herbicida hexazinone foram maiores nos solos com maior teor de C.O. (g kg-1) e argila (%). O processo de dessorção do herbicida hexazinone foi intenso para todos os solos estudados, sendo que os valores de Kf(des) foram maiores que seus respectivos Kf(sor), indicando que o processo de dessorção envolve mecanismos com menor energia de ligação que a sorção. As recomendações de doses dos herbicidas diuron e hexazinone deveriam levar em consideração outros atributos do solo, além da textura como normalmente é utilizado na prática.<br>The distinction of the recommendation rates of the residual herbicide found in the official recommendations for agriculture is normally based on three soil texture classes (sandy, medium and clayey), which are distinguished by the clay content in the soil top layer. However, the availability of the residual herbicides in the soil solution is function of the of the sorption process, which is determined mainly by the percent variations of the soil clay and organic matter content, and cationic exchange capacity (CEC). Therefore, the rate recommendations of residual herbicides by textural classes might not be adequate. Therefore, it was developed this research with the objective of evaluating the sorptive behavior of the herbicides diuron and hexazinone function of the four types of soil attributes of contrasting textural properties, and then verify the correlation of the soil attributes with the availability of these herbicides to plants. The soil samples were collected in four sugarcane production areas of São Paulo State, Brazil, presenting considerable variations in the content of clay (6 to 67%), sand (22 to 93%), cationic exchange capacity (CEC) (58.7 to 152.8 mmolc dm3) and organic carbon (O.C.) (13.95 to 19.19 g.kg-1). It was used the batch method with the radio labeled (14C) herbicide, using 2.0 g of soil for the herbicide diuron, and 4.0 g of soil for the herbicide hexazinone, and as herbicide extractor substance the CaCl2 in volume of 8.0 mL. Five concentrations of each herbicide were used, being for the diuron 0.19; 0.42; 0.84; 1.68 and 3.34 mg.L-1 and for hexazinone: 0.12; 0.22; 0.66; 2.17 and 6.03 mg.L-1. The sandy soil studied presented low sorption capacity and intense desorption of diuron, however, for clayey soils the sorption and retention process of diuron was more intense. The Kd values for diuron were higher in soils with higher content of O.C (g kg-1) and clay (%), so in general, the sorption of diuron was more correlated to the O.C. content of the soil, than to the clay content. The values of Kd, Koc, and Kf(sor) of the herbicide hexazinone were higher for the soils with higher content of O.C (g kg-1) and clay (%). The process of desorption of the herbicide hexazinone was intense for all the studied soils; the values of Kf(des) were higher than the respective Kf(sor), indicating that the process of desorption involves mechanisms with higher energy of linkage, than the sorption. The recommendations of herbicide rates of diuron and hexazinone to sugarcane should take into account other soil attributes, besides the texture each is normally used in the suggestions of the herbicide rates.

Svenska Aerogel AB has developed the material Quartzene® which is of the typeprecipitated silica and contains calcium - magnesium silicate ((Ca, Mg) SiO3). Thematerial is used for molecular filtration of contaminated air. Qartzene™, which is inpellet form, is porous and has a high internal surface which is a requirement for themolecular filtration. With the use of various impregnations, filtration can affect thedesired outcome. As an example Quartzene® can be impregnated with Potassiumhydroxide and clear the air of Sulfur dioxide, SO2 (Svenska Aerogel AB, n.d).Svenska Aerogel AB has developed Quartzene® further and new areas of application hasarosee, one of these areas is how the material function within dehumidification. Thepurpose of this study is to research and analyze how different impregnation salts effecthow Quartzene® function in terms of moisture absorption and moisture desorption.Quartzene® is a hygroscopic material, which is a material that easily absorbs and exudatesmoisture from the air. Materials with high porosity absorb moisture by adsorption andcapillary condensation. A hygroscopic material strives for equilibrium with ambientenvironment which is illustrated in a sorption curve where moisture absorption is set inrelation to relative humidity. In this study the jar method is used to measure moistureabsorption, this is shown with the use of sorption curves. The jar method uses saturatesalt solutions to create environments whit a set relative humidity. Quartzene® – pellets areplaced in jars and weighed at regular intervals to determine the moisture absorption.The results of this study indicate that impregnations affect the way that Quartzene®function in terms of moisture absorption and moisture desorption. Some of theimpregnations affect the material to absorb more moisture than Quartzene® that has notbeen impregnated, while others affect the material to absorb less moisture. The resultsalso show that sodium – based impregnation gives similar results as Quartzene® that hasnot been impregnated.

Increasing concern about the pollution of environment by inorganic and organic chemicals arising from naturally occurring ecological events and industrial processes has created a need for the search of new techniques in the removal of these contaminants. One of the natural material that can be used in such processes is clay. Clay minerals have large surface areas and high cation exchange capacities which enables them to be modified by cationic surfactants. The material prepared, often called as &amp<br>#8216<br>organoclay&amp<br>#8217<br>, can be used to remove hydrophobic organic and anionic contaminants from polluted water. Among the anionic contaminants, oxyanions such as nitrate, chromate are detrimental to human life and environment even at &micro<br>g/L- mg/L levels. Application of organoclays for their removal from polluted water appears as one of the practical and rather cheap solution. In this study, a local clay from Ankara-Kalecik (Han&ccedil<br>ili Bentonite) was modified by hexadecyltrimethylammonium bromide (HDTMA-Br) to a level of twice of its cation exchange capacity. This process alters the negatively charged surface of the clay into a positively charged one, providing sites for the removal of anionic contaminants. In this study, the degree of HDTMA+ uptake by the clay within a period of eight hours is found to be 97% of the initial amount added. In desorption studies it was revealed that only about 1% of the sorbed HTDMA+ was leached in a seven days of water-organoclay interaction revealing a rather stable organoclay structure in aqeous media. Sorption experiments with nitrate, borate, and chromate solutions were performed in order to determine the anion sorption capacity of the organoclays prepared. It turns out that while untreated clay has insignificant capacity, the modified clay can remove considerable amount of nitrate and chromate ions from aqeous solutions. While the nitrate sorption was increased about eleven fold, change in chromate sorption was reached to a level of twenty fold compared to that of the untreated clay. Sorption data for nitrate and chromate are both well described by the Langmuir isotherms. No significant change was observed in case of borate-organoclay interaction. Desorption of nitrate and chromate ions from organoclay surface were also investigated. Sorption of these oxyanions were found to be almost irreversible in aqeous media. The results imply that a properly prepared organoclay can be used for the removal of oxyanions, such as nitrate and chromate from polluted water systems.

O objetivo deste trabalho foi avaliar o método de fluxo em colunas de solo e o método “batch” na determinação da sorção de imazaquin; avaliar a cinética de sorção e dessorção do imazaquin em solos através do método “batch” e; determinar a sorção dependente do tempo do diuron e sua interação com o tamanho dos agregados do solo. Na primeira parte foi avaliada a sorção e a mobilidade do imazaquin em solos com diferentes características químicas, físicas e mineralógicas utilizando as técnicas de deslocamento miscível e “batch”. Com os dados de lixiviação do imazaquin utilizou-se um modelo matemático bicontínuo que considera a sorção sob condições de não-equilíbrio. O modelo forneceu alguns parâmetros de sorção e transporte do imazaquin através da coluna. No método “batch” os dados experimentais foram ajustados à equação de Freundlich, que também forneceu parâmetros de sorção. Na segunda parte foram estudadas a sorção e dessorção do imazaquin em solos com diferentes características químicas e mineralógicas através do uso de isotermas e estudos de cinética e assim quantificar a histerese no processo de sorção-dessorção. Para todos estes ensaios foi utilizado o método “batch”, com os dados das isotermas de sorção e dessorção sendo ajustados pela equação de Freundlich. Os dados de cinética foram ajustados pela equação de Elovich. No terceira e última parte foi avaliada a sorção do diuron em função do tempo de incubação e do tamanho do agregado do solo, assim como a interação destes dois fatores. Em períodos pré-determinados, amostras de solo incubadas com o diuron foram extraídas e oxidadas, obtendo-se as frações em equilíbrio com a solução, sorvida e resíduo-ligado. Com relação aos resultados, o imazaquin apresentou baixa sorção e alta mobilidade em coluna para todos os solos estudados, principalmente o mais arenoso. A curva de eluição do imazaquin ajustou-se ao modelo matemático que considera a sorção ocorrendo sob condição de não-equilíbrio. O método do deslocamento miscível apresentou os menores valores de Kd para o imazaquin, comparado ao método “batch”, sendo atribuída esta diferença ao não-equilíbrio no processo de sorção durante o transporte do imazaquin na coluna. No estudo de sorção/dessorção do imazaquin constatou-se que os coeficientes de sorção do imazaquin foram baixos para todos os solos, com a menor sorção sendo observada no solo RQ que apresenta baixos teores de argila e carbono orgânico do solo. Os coeficientes de dessorção do imazaquin foram maiores que seus coeficientes de sorção, demonstrando ocorrer histerese na dessorção. A histerese foi observada em todos os solos. A sorção do imazaquin ocorreu em duas fases, sendo que a segunda fase, mais lenta, é influenciada por processos difusivos. No estudo de incubação do diuron, houve correlação negativa entre o diuron extraído em solução de CaCl2 e o conteúdo de carbono orgânico no solo. Não foi observada interação entre o tempo de incubação e o tamanho dos agregados, evidenciando que a sorção dependente do tempo, neste caso, não está relacionada à estrutura do solo. A fração sorvida de diuron aumentou com o tempo de incubação, indicando que o processo de sorção é dependente do tempo.<br>The aim of this study was to evaluate the column flow and batch methods in the measurement of the imazaquin sorption: to evaluate de sorption kinetic and desorption of the imazaquin in soil by batch method and; to evaluate the time-dependent sorption of the diuron and the interaction with the aggregate size of the soil. In the first part it was evaluated the imazaquin mobility and sorption in soils with different mineralogical, physical and chemical characteristics. The imazaquin breakthrough curves were fitted by a mathematical model that considers the nonequilibrium sorption. The model provided sorption and transport parameters. In the batch method the experimental data were fitted to Freudlinch equation, which provided also the sorption parameters. In the second part were studied the imazaquin sorption/desorption in soils with with different mineralogical, physical and chemical characteristics. It was carried out by batch method and kinetics studies, which allowed quantifying the hysteresis in the sorption-desorption process. The experimental data were fitted to the Elovich equation. In the third and last part it was evaluated the time dependent sorption of the diuron and the influence of the aging and aggregate size. Samples of aged soil were extracted and combusted in pre-determined periods. It was obtained the equilibrium, sorbed and bound-residue fractions. Regarding the results, the imazaquin showed low sorption and high mobility in columns for the three soils, mainly the sandy soil. The imazaquin breakthrough curve fitted to the mathematical model that considers the nonequilibrium sorption. The miscible displacement method showed the lower values of the Kd than the batch method. This result was attributed to the nonequilibrium sorption during the imazaquin transport through the column. In the sorption/desorption study it was observed that the imazaquin sorption coefficients were low for the three soils. The RQ soil showed the lowest Kd value. This soil presented the lower clay and organic carbon content. The imazaquin desorption coefficients were higher than the sorption coefficients, evidencing that occurred hysteresis in the process. The imazaquin sorption occurred in two phases. The second phase, which is slower, seems to be influenced by diffusive processes. In the aging experiment it was noted negative correlation between extracted diuron in CaCl2 solution and organic carbon content. It was not observed interaction between the incubation period and aggregate size, demonstrating that the time dependent sorption, in this case, is not related to the soil structure. The sorbed fraction of the diuron increased during the aging, indicating that the sorption process is time dependent.

L'épandage des boues d'épuration est un mode de valorisation à la fois écologique et économique pour autant que l'on maitrise leur qualité et notamment la concentration des métaux lourds mobilisables. Le cuivre est une molécule très répandue, naturelle dans l'environnement, largement utilisée dans l'industrie et l'agriculture. En conséquence, les quantités de cuivre dans l'environnement ont augmenté, de sorte que ce dernier a été choisi dans cette étude comme représentant de la pollution anthropique pour évaluer sa mobilité en fonction de la qualité des boues épandues et des sols. 9 boues classiques et 2 sols (Sol d’herbe (de France) et sol de riz (du Vietnam)) ont été étudiés ainsi que des boues granulaires. Une méthodologie est proposée pour évaluer l'effet de la boue et de l'origine du sol sur la capacité de lessivage du cuivre lors de l'épandage des boues pour les activités agricoles. Les essais de désorption dans les colonnes de sol amendé par des boues ont montré que: a) quelle que soit l'origine du sol amendé, les boues de lit de roseaux (LR), séchées (BCD), centrifugées (BC) ont présenté une libération de Cu inférieure à 2% tandis que les boues de filtre-presse (BFP), digérées (BD), épaissies (BE) et calcaires (BCh) ont amélioré la disponibilité de Cu dans le sol; b) La lixiviation du cuivre dans le sol d’herbe (du France) amendé par des boues granulaires était supérieure à celle mesurée pour les échantillons classiquesde boues; c) Dans le sol de riz (de Vietnam), l'épandage des boues granulaires a limité la désorption de cuivre par rapport aux échantillons de boue (BCh), de filtre-presse (BFP), digérée (BD) ou centrifugée (BC). Quatre mécanismes sont proposés pour expliquer le devenir du Cu dans les sols: 1) le contrôle; 2) le groupe de Cp1, Cp2, BC, LR and BCD; 3) le groupe de BCh, BD, BE, BFP et 4) le groupe de boue granulaire. Il est constaté que pour le sol de riz contenant une faible teneur en matière organique, l'application de boues granulaires ou d'autres types de boue tels que les boues compostées ou séchées peut non seulement augmenter la teneur en éléments nutritifs, mais aussi réduire la capacité de lixiviation du cuivre<br>The spreading of sewage sludge is both ecological and economical in sofar as their quality is controlled and in particular the low level of the heavy metals available. Copper is a very common substance, naturally occurring in the environment, widely used in industry and agriculture. As a result, quantities of copper in the environment have increased, so it has been selected in this study as representing human-induced pollution to assess its mobility in relation to the quality of sludge and soil. 9 different sludges and 2 soils (grass soil from France and paddy soil from Vietnam) were studied as well as granular sludge. A methodology was developed to evaluate the effect of sludge and soil origin on copper leaching ability during sludge application for agricultural activities. Desorption tests in soil-amended sludge columns showed that: a) Whateverthe origin of soil, the centri-dried (BCD), centrifuged (BC), reed-bed (LR) sludges presented a Cu release lower than 2% while filter-pressed (BFP), digested (BD), thickened (BE) and limed (BCh) sludge amended soils increased Cu availability in soil; b) the copper leaching of granular sludge amended grass soil was higher than those measured for conventional sludge samples; c) in paddy soil, landspreading of granular sludge limited the Cu desorption compared to limed (BCh), filter-press (BFP), digested (BD) and centrifuged (BC) sludge samples. Four mechanisms groups are proposed to explain the fate of Cu in soils: 1) the control; 2) the group of Cp1, Cp2, BC, LR and BCD; 3) the group of BCh BD BE and BFP, and 4) the group of granular sludge. It is found that paddy soil containing low organic matter, application of granular sludge orother types such as composted or dried sludge can not only increase the nutrient content but also reduce the leaching capacity of copper

U okviru ovog istraživanja ispitani su: 1. Optimalni uslovi&nbsp; zaeksperimente biodegradacije policikličnih aromatičnih ugljovodonika sa istim irazličitim brojem prstenova; 2. Uticaj struture&nbsp; i matriksa na biodegradacijupolicikličnih aromatičnih ugljovodonika sa istim brojem prstenova; 3.Fitotoksičnost biljaka&nbsp; (testovi klijavosti i usvajanje policikličnih aromatičnihugljovodonika); 4. Procena&nbsp; potencijalne&nbsp; biodostupne frakcije primenomrazličitih hemijskih sorbenata (HPCD, &beta;CD&nbsp; i&nbsp; MCD, XAD4 i TenaxTA)&nbsp; i 5.Korelacija dobijenih rezultata&nbsp; testovima biodegradacije, testovima klijavosti,testovima fitotoksičnosti i rezultata dobijenih iz eksperimenta procenebiodostupnosti hemijskim testovima.&nbsp; Rezultati su pokazali da se&nbsp; optimalniuslovi za biodegradaciju&nbsp; postižu dodatkom mineralnih medijuma, inokuluma isurfaktanata.&nbsp; Posmatrajući uticaj sadržaja gline i organske materije i strukturemolekula,&nbsp; najveći stepen biorazgradnje ima fluoranten, &scaron;to je u skladu sanjegovim fizičko-hemijskim osobinama, dok se sadržaj pirena i krizena nijemogao jasno korelirati sa sadržajem organske materije i gline.&nbsp; &Scaron;to se tičetestova fitotoksičnosti,&nbsp; sva semena su proklijala, &scaron;to govori u prilog tome&nbsp; dame&scaron;avina ovih kontaminanata&nbsp; pri ispitivanim koncentracijama&nbsp; nije inhibiralaklijanje biljaka.&nbsp; Testovi usvojivosti ispitivanih PAH-ova su pokazali da jenajmanji procenat usvojivosti semenom dobijen za benzo(a)piren, &scaron;to se možeobjasniti njegovom kompleksnijom strukturom. Hemijskim testovima zaprocenu biodostupnosti je sa druge strane pokazano da se desorpcija u prisustvuMCD, XAD4 smole i Tenaxa može koristiti kao jednostavna metoda za procenupotencijalne biodostupne&nbsp; frakcije organskih jedinjenja u sistemima sediment&nbsp; -voda.<br>The aim of this study was to investigate: 1. The optimal conditions for&nbsp;the biodegradation of polycyclic aromatic hydrocarbons with the same and&nbsp;different numbers of rings; 2. The impact of structure and matrix&nbsp;biodegradation of polycyclic aromatic hydrocarbons with the same number of&nbsp;rings; 3. Phytotoxicity (germination tests and polycyclic aromatic hydrocarbon&nbsp;uptake); 4. The means for assessing the bioavailable fractions using various&nbsp;chemical sorbents (HPCD, &beta;CD, MCD, XAD4 and &nbsp;TenaxTA) and 5. The&nbsp;correlation between the results of the biodegradation tests, germination tests,&nbsp;phytotoxicity tests and the results obtained from the experiments in the&nbsp;assessment of bioavailability and chemical tests. The results showed that the&nbsp;optimal conditions for biodegradation are achieved by the addition of mineral&nbsp;media, inoculum and surfactants. When considering the effect of the contents of&nbsp;clay and organic matter and the structure of the molecules, the highest degree of&nbsp;biodegradation was observed with fluoranthene,&nbsp; which is in line with its&nbsp;physico-chemical properties. The concentrations of pyrene and chrysene were&nbsp;not clearly correlated with the organic matter and clay contents. During thephytotoxicity tests, all seeds sprouted, which speaks in favor of a mixture of&nbsp;these contaminants not inhibiting the germination of the plants. Tests for the&nbsp;uptake of the investigated PAHs showed that the lowest percentage seed uptake&nbsp;was for benzo(a)pyrene, which is explained by its more complex structure.&nbsp;Chemical tests for evaluating bioavailability have shown that desorption in the&nbsp;presence of MCD, XAD4 and Tenax resins can be used as a simple method for&nbsp;the evaluation of a potential bioavailable fraction of organic compounds in&nbsp;water-sediment systems.

Le but de ce travail a ete d'etudier la separation de melanges de composes organo-volatils par adsorption-desorption sur charbon actif. Notre recherche s'est deroulee en deux parties : - dans la premiere partie, des donnees sur les equilibres d'adsorption des composes purs et des melanges ont ete obtenues. Elles nous ont permis de connaitre les differentes affinites des composes avec le support, d'aborder les phenomenes de competition et donc la separation. Des modeles permettant de prevoir les equilibres d'adsorption multicomposes et l'effet de la temperature ont pu etre verifies. - dans la seconde partie, des cycles d'adsorption par paliers de temperature sur des filtres contenant deux sections de charbon actif ont ete mis en place. Globalement, a partir d'un melange contenant 50% de dichloromethane / 50% de 1,2-dichloroethane, il est possible de recuperer sur la seconde section le dichloromethane avec un degre de purete > 99%. Sur la premiere section, le 1,2-dichloroethane est desorbe avec une purete > 80%. Ces experiences ont permis de valider le modele etabli pour prevoir les courbes de percee de melanges a partir de donnees sur les equilibres d'adsorption des composes purs. L'ensemble de ce travail a permis de verifier la faisabilite de la separation et de la recuperation selective de solvants par adsorption desorption et de fixer ses limites.

<p>The sorption/desorption behaviour of n-hexane in high molarmass linear polyethylene (PE) and branched PEs with 0.39 and5.09 hexyl branches per 100 main chain C atoms andcrystallinities between 4 and 82% at 298 K has been studied.Crystal core contents determined by Raman spectroscopy werealways lower than those determined by density measurements. Then-hexane solubilities in the copolymers depended in anon-linear manner on the content of penetrable polymercomponent and were lower for homogeneous copolymers than forheterogeneous copolymers at the same contents of penetrablecomponent. The solubility of hexane in the linear PE sampleswas proportional to the volume fraction of the penetrablepolymer and the solubility was low in comparison with that ofthe branched PE of the same crystallinity. TheCohen-Turnbull-Fujita (CTF) free volume theory was capable ofdescribing the desorption process in the PEs studied. Theconcentration dependence of the thermodynamic diffusivitypredicted by the CTF free volume theory was confirmed by thedata obtained by the differential method, and the differencesbetween the results obtained by the integral and differentialmethods were within the margins of experimental error. Thedependence of the fractional free volume of the penetrablephases on the phase composition suggests that mass transporttakes place from the liquid-like component to the interfacialcomponent and that the penetrant molecules are trapped at theinterfacial sites. The linear PE samples showed a physicallyrealistic trend with a decrease in the geometrical impedancefactor (t) with decreasing degree of crystallinity, whereas theopposite trend was obtained for the copolymers. The decrease int with increasing crystallinity in the copolymers may beexplained by the presence of wide crystal lamellae in the lowcrystallinity samples.</p><p>A novel melt-extrusion method was used to createcircumferential chain orientation in pipes of crosslinked PE.The microstructure of the pipes was characterized usingdifferential scanning calorimetry (DSC), density measurements,X-ray diffraction, infrared dichroism and contractionmeasurements. The mechanical properties were assessed byuniaxial tensile tests. The maximum degree of circumferentialorientation was obtained at the inner wall of the orientedpipe. The oriented pipe material exhibited a 5-15% higherdegree of crystallinity and a greater crystal thickness thanconventionally crosslinked pipe. The circumferential and axialmoduli of the oriented, crosslinked pipe were greater than thecorresponding moduli of the non-oriented crosslinked pipe.</p><p>Blends of single-site materials of linear PE andethyl-branched PE were prepared using solution- and melt-mixingmethods. The thermal properties of the blends were studied byDSC and results obtained by the two mixing methods werecompared. Data obtained for heats of melting andcrystallization, melting and crystallization peak temperaturesand melting and crystallization temperature profiles wereessentially the same for the samples obtained by the two mixingmethods. The heat associated with the high temperature meltingpeak of the blend samples obtained by both preparation methodsafter crystallization at 398 K was higher than that of thelinear polyethylene included in the blends, suggesting that apart of the branched polyethylene crystallized at 398 K.</p><p><b>Key words:</b><i>n</i>-Hexane diffusion, polyethylene, free volume,solubility, sorption, desorption, mechanical properties,orientation, thermal properties, blend.</p>

Sr-90 and Cs-137 are two key fission products that are important in a number of radioactive waste or contamination clean-up scenarios. This thesis investigates the sorptiondesorption behaviour of these two radionuclides with a number of sorbents relevant to one of the legacy waste storage ponds on the Sellafield site. Sorption-desorption studies were undertaken on brucite (Mg(OH)2), UO2 and UO3 powders to represent components of the fine particulate sludge that has accumulated on the bottom of the pond, resulting from corrosion of the Magnox fuel elements. Brucite was found not to have a significant interaction with Sr-90 or Cs-137. However, organic molecules in the form of humic acid and Pseudanabaena catenata cyanobacterial growth supernatant were both found to enhance sorption interactions of Sr-90 with brucite. The effect of humic acid was pH dependent and appeared to control both sorption and desorption behaviour at pH 11.5. Uranium oxides had the most significant effect on controlling Sr-90 and Cs-137 sorption-desorption behaviour. In this work X-Ray Absorption Spectroscopy (XAS) showed that 90Sr sorbed strongly to both uranium oxides as a bidentate inner-sphere complex. Humic acid did not appear to alter the interaction of Sr-90 with UO2. For Cs-137 there was a significant, reversible interaction with both oxides, although the interaction was far stronger with UO3. Successful detection of stable Sr and Cs isotopes on uranium oxides was achieved with Laser Induced Breakdown Spectroscopy (LIBS).

Cette thèse porte sur le comportement d’un composé prioritaire au titre de la Directive Cadre sur l’Eau au niveau européen : le tributylétain (TBT) et ses métabolites (dibutylétain (DBT) et monobutylétain (MBT)). On s’intéresse plus particulièrement aux eaux usées domestiques lors de leur transit dans deux stations d’épuration par lagunage naturel (STEP), traitement adapté aux effluents provenant des zones faiblement urbanisées. Ce travail de thèse vient combler le manque de résultats scientifiques sur (1) le niveau des concentrations en butylétains dans les effluents domestiques des zones peu urbanisées en entrée des stations par lagunage et en sortie après traitement ; (2) l’efficacité du traitement par lagunage à éliminer les butylétains ; (3)l’identification des processus qui contrôlent le devenir de ces éléments au cours du traitement.Les butylétains sont mesurés dans les matrices particulaires, dissoutes et dans les boues, par couplage GC-ICP-MS, dans toutes les étapes du traitement par lagunage de deux communes rurales du département de l’Hérault (34,France) : Gigean (6000 eq-hab.) et Montbazin (4500 eq-hab.). On montre que les trois espèces butylées sont systématiquement présentes dans tous les échantillons prélevés sur les deux STEP. Les butylétains arrivent principalement sous forme particulaire dans les eaux brutes en entrée des stations. Au cours du traitement, les processus de sorption sur les particules en suspension et la décantation de ces dernières au fond de chaque bassin sont les principaux facteurs permettant l’élimination des butylétains. Les premiers bassins anaérobies, de grande profondeur et de long temps de séjour, permettent l’élimination de plus de 60% à Gigean (93% à Montbazin) des butylétains. Les boues de fond de chaque bassin montrent des concentrations élevées en butylétains. La remise en suspension des butylétains est notée dans les derniers bassins de finition, peu profonds, ce qui peut être due à la re-stratification thermique. En sortie de station, malgré les abattements importants, des concentrations non négligeables en butylétains (12 à 228 et 1.8 à 15 ng(Sn).L-1 respectivement pour Montbazin et Gigean) sont rejetées dans le milieu récepteur. Des expériences de sorption basées sur la mise en contact de butylétains avec des boues de fond de bassin diluées ont été effectuées selon plusieurs approches expérimentales. On a ainsi montré que (1) la distribution des espèces MBT, DBT, TBT, entre les phases solide et liquide, est variable d’un test à l’autre selon les conditions opératoires ; (2) l’affinité entre les butylétains et la boue est importante, quelle que soit sa provenance. 98% des butylétains se retrouvent dans la phase solide, du fait de leur hydrophobicité. Le coefficient de distribution Kd entre le TBT et les boues est plus élevé que celui obtenu pour d’autres type de phases solides (75000 L.kg- 1) ; (3) le processus de sorption est rapide. De plus des processus de sorption, désorption et déalkylation du TBT, expliquant les variations des concentrations en MBT et DBT dans la phase solide ont été identifiés. La désorption du TBT est rapide. Il se dégrade dans la phase liquide en DBT dont une partie se transforme en MBT. La sorption du MBT sur les boues a été systématiquement mesurée. Le phénomène de sorption n’est donc pas complètement réversible au cours du temps. Ces résultats contribuent à expliquer les dysfonctionnements observés dans les stations de traitement par lagunage, par exemple lors d’apports directs d’eau de pluie.Cette thèse démontre la présence systématique des butylétains dans les stations d’épuration par lagunage naturel. Les données acquises in-situ couplées à des essais en laboratoire permettent de comprendre le comportement de ces composés lors de ce traitement : la fraction solide joue un rôle clé dans les processus de sorption-désorption-(bio)dégradation des butylétains<br>This thesis deals with the behavior of a priority compound on the basis of the framework Directive on water at European level: tributyltin (TBT) ) and its metabolites (dibutyltin (DBT) and monobutyltin (MBT)). The study is focused on two waste stabilization pond treatment plants (WSP), which is an appropriate treatment to domestic effluents from sparsely urbanized areas.This thesis comes to fill the lack of scientific results on (1) the level of butyltin concentrations in domestic effluents from sparsely urbanized areas, in the input of the WSP and the output after treatment; (2) the efficiency of butyltins elimination by the WSP treatment; (3) the identification of the processes that control the fate of these elements during the treatment.Butyltins are measured in particulate and dissolved matrices and in sludge, by GC-ICP-MS, in all stages of the treatment by lagooning of two villages of the Department of Hérault (34, France): Gigean (6000 p.e.) and Montbazin (4500 p.e.).It is shown that the three butyltin species are consistently present in all samples taken from the two WSP. Butyltins arrive primarily in particulate form in the raw water. During treatment, the processes of sorption onto particulate matter and the settling of the latter at the bottom of each basin are the main factors for the elimination of butyltins. The first anaerobic ponds, characterized by deep depth and long residence times, allow the elimination of more than 60% Gigean (93% at Montbazin) of butyltins. Bottom sludge of each basin show high butyltins concentrations. The resuspension of butyltins is noted in the last maturation ponds, characterized by shallow depth, which may be due to re-thermal stratification. At the outlet, despite significant butyltin removal, concentrations in butyltins remain high (12 to 228 and 1.8 to 15 ng (Sn). L-1, respectively for Montbazin and Gigean).Laboratory batch experiments were conducted to study sorption processes following several experimental protocols. It was thus shown that: (1) the distribution of the butyltin species between solid and liquid phases is different from one test to another according to the operating conditions; (2) the affinity between butyltins and bottom sludge is important, regardless of its provenance. 98% of the butyltins are found in the solid phase, due to their hydrophobicity. The TBT sludge-water partition coefficient is higher than that obtained for other type of solid phases (75000 L.kg-1); (3) the process of sorption is fast.Moreover processes of sorption, desorption and dealkylation of TBT, explaining changes in concentrations of MBT and DBT in the solid phase were identified. Desorption of TBT is fast. It degrades in the liquid phase in DBT which part turns into MBT. The sorption of MBT on sludge has been systematically measured. Therefore, the sorption phenomenon is not completely reversible over time. These results help to explain the dysfunctions observed in WSP, for example after direct inputs of rainwater.This thesis shows the systematic presence of butyltin in waste stabilization pond treatment plants. In-situ data coupled with laboratory tests allow to understand the behaviour of these compounds during this treatment: the solid fraction plays a key role in the processes of sorption-desorption-(bio) degradation of butyltins

Polyelektrolyte (PEs) bilden eine große Klasse von Materialien, die in der wissenschaftlichen Forschung immer mehr Beachtung findet. Aufgrund der Lange-Bereich Elektrostatic ist das theoretische Verständnis von PE-Lösungen im Vergleich zu ihren neutralen Gegenstücken noch relativ schlecht gewesen, dadurch die Rationalisierung der Gegenionskondensation auf hochgeladenen PEs herausfordern. Die Komplexität des Problems wird noch zusätzlich durch die gleichzeitige Anwesenheit monovalenter und divalenter Gegenionen in der Lösung, was vielen biologische Umgebungen entspricht, erhöht. Dies beeinflusst die PE-Protein Komplexierungen, damit ihren Funktionen und Anwendungen in der Biomedizin und Biotechnologie. In dieser Arbeit führen wir eine umfassende Analyse der Ladungs- und Hydratationsstruktur von dendritischen PEs in einem monovalenten Salz unter Verwendung von atomistischen Molekulardynamik (MD) Computersimulationen mit explizitem Wasser durch. Darüber hinaus untersuchen der kompetitiven Adsorption der monovalenten und divalenten Gegenionen am globulären PE mit Hilfe theoretischer Mean-Field-Modelle, vergröberter und atomistischer (expliziter) Wasser-Simulationen und Kalorimetrie-Experimenten. Wir befassen uns mit der Herausforderung, eine genau definierte effektive Ladung und ein Oberflächenpotential der PEs für praktische Anwendungen zu finden, und präsentieren ein neuartiges kompetitives Ionenbindungsmodell, das einen aussagekräftigen Vergleich zwischen Theorie, Simulationen und Experimenten gewährleistet. Diese Arbeit stellt eine systematische elektrostatischen Beschreibung von PE vor, untersucht die thermodynamische PE-Wasser Signatur und analysiert die kompetitiven Bindung von monovalenten und divalenten Gegenionen an PEs. Es wird ein tieferer Einblick in die physikochemischen Aspekte von PE-Gegenionen- und PE-Wasser-Wechselwirkungen erhalten, was für das rationale Design von PEs auf einer gezielten Anwendungsbasis von entscheidender Bedeutung ist.<br>Polyelectrolytes (PEs) represent a broad class of materials that are getting an increasing attention in the scientific community. However, due to the long-range electrostatics, the theoretical understanding of PE solutions has been relatively poor compared to their neutral counterparts, thereby challenging the rationalization of the counterion condensation on highly charged PEs. Moreover, the counter-intuitive footprint of PE-water thermodynamics, and the simultaneous presence of the divalent and the monovalent counterions in the solution, as is reminiscent of many biological environments, escalates the complexity and richness of the problem. This affects the PE-proteins complexations, and thus their functions, applications in biomedicine and biotechnology. In this thesis, we conduct a comprehensive analysis of the charge and hydration structure of dendritic PEs in a monovalent salt using all-atom explicit-water molecular dynamics computer simulations, and investigate a competitive sorption of mono- versus divalent ions on globular PEs using mean-field theoretical models, all-atom and coarse-grained simulations and calorimetry experiments. We address the challenges of obtaining a well-defined effective charge and surface potential of the PE for practical applications and present a novel competitive ion binding model, ensuring a meaningful comparison between theory, simulations and experiments. This thesis lays out a systematic PE electrostatic characterization, explores PE-water thermodynamics, and analyses the competitive binding of divalent and monovalent counterions on the PE. A deeper insight into the physicochemical aspects of PE-counterion and PE-water interactions is achieved, which is vital towards the rational design of PEs on a targeted application basis.

This thesis examines the use of electrochemically treated viscose rayon based activated carbon cloth (ACC) for the removal of metal ions from aqueous effluent streams. Two types of treatment were performed: (i) electrochemical oxidation and (ii) electrochemical reduction to enhance cation and anion sorption capacities of the ACC, respectively. Electrochemical oxidation resulted in a loss of 61% BET surface area due to blockage of pores through formation of carboxylic acidic groups but its cation exchange capacity and oxygen content increased by 365% and 121%, respectively. The optimum constant current at which a combination of applied current and oxidation time at any extent of oxidation to produce ACC of maximum cation exchange capacity was found to be 1.1 A, with voltage of 4.2 V and current density of 0.8 mA/m2. Batch sorption experiments showed that the maximum copper and lead sorption capacities for electrochemically oxidised ACC increased 17 and 4 times, respectively, for noncompetitive sorption and 8.8 and 8.6 times, respectively for competitive sorption. Therefore, electrochemically oxidised ACC is an effective adsorbent for treating aqueous solution contaminated with copper/lead in both single component and multi-component systems. Industrial wastewaters are multicomponent systems, therefore, electrochemical oxidation of ACC is an efficient way of enhancing lead and copper ions sorptive capacity for industrial wastewater treatment. Electrochemical reduction resulted in a loss of 28% BET surface area due to formation of ether groups but its anion exchange capacity increased by 292%. The optimum constant current at which a combination of applied current and reduction time at any extent of reduction to produce ACC of maximum anion exchange capacity was found to be 5.5 A, with voltage of 9.8 V and current density of 6.4 mA/m2. Batch sorption experiments showed that the maximum chromium(VI) sorption capacity for electrochemically reduced ACC increased 2.12 times, with highest maximum chromium(VI) sorption capacity of 3.8 mmol/g at solution pH 4. Most industrial wastewaters contaminated with chromium(VI) are highly acidic, therefore, electrochemical reduction of ACC is an efficient way of enhancing chromium(VI) sorptive capacity for industrial wastewater treatment.

Prirodna organska materija zemlji&scaron;ta/sedimenata predstavlja glavnu oblastza sorpciju hidrofobnih organskih jedinjenja, a njene osobine utiču na stepenretencije i konsekventnu (bio)dostupnost organskih jedinjenja. Da bi se procenioekotoksikolo&scaron;ki rizik zagađenih zemlji&scaron;ta/sedimenata po okolinu, dizajniralaodgovarajuća strategija remedijacije ili predvidela sudbina i transport organskihpolutanata u zagađenim zonama, neophodno je razumevanje mehanizma sorpcije idesorpcije na nivou mehanizma uspostavljenih veza. U radu je izvr&scaron;eno ispitivanjesorpcije i desorpcije odabranih hidrofobnih organskih polutanata, pentahlorbenzenai lindana, na sekvencijalno ekstrahovanim huminskim kiselinama i huminima izjednog uzorka sedimenta u cilju pronalaženja veze između strukturnihkarakteristika izolovanih huminskih kiselina i humina i sorpcionih i desorpcionihparametara. Afinitet za sorpciju, nelinearnost izotermi i prividna sorpciono-desorpciona histereza korelirani su&nbsp; sa osobinama sorbenata dobijenim izelementarne i FTIR spektroskopske analize. Predloženo je da je mehanizamsorpcije na huminskim kiselinama rezultat odigravanja raspodele i specifičneadsorpcije, pri čemu se pri nižim koncentracijama pentahlorbenzena i lindana prvopopune sorpciona mesta u kondenzovanoj aromatičnoj oblasti, a tek potom privi&scaron;im koncentracijama sorpciona mesta u amorfnim alifatičnim oblastima.Sveukupno vi&scaron;i koeficijenti nelinearnosti dobijeni za sorpciju pentahlorbenzena na huminskim kiselinama u odnosu na nelinearnost sorpcionih izotermi lindana, ukazuju na to da u ukupnoj sorpciji pentahlorbenzena veći značaj ima mehanizam raspodele i sme&scaron;tanje molekula pentahlorbenzena u hidrofobne &scaron;upljine huminskih kiselina, u odnosu na specifičnu adsorpciju. Ovi zaključci su potvrđeni rezultatima spektroskopskih istraživanja interakcija&nbsp; odabranih organskih jedinjenja i N-metilformamida. Predloženi mehanizam sorpcije ne može objasniti sorpciju pentahlorbenzena i lindana na uzorcima humina, većje pretpostavljeno da nelinearna sorpcija za uzorke humina može biti rezultat ostvarivanja povr&scaron;inskih interakcija, a visoki afinitet za sorpciju rezultat je raspodele organskih jedinjenja u amorfnim alifatičnim oblastima koje pružaju odlično okruženje za sorpciju.U cilju daljeg proučavanja mehanizma sorpcije, izvr&scaron;eno je ispitivanje kinetikedesorpcije tri odabrana hidrofobna organskajedinjenja, pentahlorbenzena, lindana ipentahloranilina, posredstvom&nbsp; čvrstog adsorbenta, XAD-4 makroporoznejonoizmenjivačke smole. Na osnovu rezultata dobijenih za uzorak sedimenta ifrakciju &lt; 125 &micro;m za dva ravnotežna vremena (15 i 90 dana) i za sva odabranaorganska jedinjenja može se zaključiti da se za procenu potencijalne (bio)dostupnefrakcije organskih jedinjenja može koristiti jednostavna desorpcija u prisustvuXAD-4 makroporozne jonoizmenjivačke smole i to na dva načina: (1) ekstrakcijomsedimenta tokom 24 časa, kada frakcija koja se desorbuje odgovara frakcijijedinjenja koja se nalazi u brzo-desorbujućem domenu organske materije, ili (2)ekstrakcijom tokom 6 časova, kada frakcija koja se desorbuje odgovara polovinione frakcije jedinjenja koja se nalazi u brzo-desorbujućem domenu organskematerije.<br>Natural organic matter of soil/sediment make the main region for&nbsp;sorption of hydrophobic organic compounds, ant its properties influence the degree&nbsp;of retention and, consequently, (bio)availability of organic compounds. In order to&nbsp;assess the ecotoxicological risks of contaminated soils/sediments to the&nbsp;environment and design the appropriate remediation strategy or predict the fate and&nbsp;transport of organic pollutants in contaminated zones, it is necessary to understand&nbsp;the mechanisms of sorption/desorption at the level of the mechanism of established&nbsp;bonds. Study of the sorption and desorption of selected hydrophobic organic&nbsp;pollutants, pentachlorobenzene and lindane, on sequentially extracted humic acids&nbsp;and humins from a single sediment sample with the aim of finding the relationship&nbsp;between the structural characteristics of the isolated humic acids and humin and&nbsp;sorption and desorption parameters. Sorption affinity, nonlinearity of isotherms,&nbsp;and apparent sorption-desorption hysteresis were correlated to the sorbent&nbsp;characteristics obtained from elemental analysis and FTIR spectroscopic data. The&nbsp;proposed sorption mechanism on humic acids assumes that at low concentrations&nbsp;of pentachlorobenzene and lindane the sorption sites in the condensed aromatic&nbsp;region are occupied first, and then, at their higher concentrations, the sorption sites&nbsp;in the amorphous and aliphatic regions. Generally higher nonlinearity coefficient obtained for the sorption of pentachlorobenzene on &nbsp;umic acids compared with the nonlinearity of sorption isotherms for lindane, indicate that in the overall sorption of pentachlorobenzene of higher significance is the &nbsp;echanism of distribution and insertion of pentachlorobenzene molecule into hydrophobic dips of humic acids, compared to specific adsorption. These conclusions were confirmed with the results of spectroscopic investigation of &nbsp;intermolecular interaction of chosen organic compounds and N-methylformamide.Since suggested sorption mechanism could not explain sorption of &nbsp;pentachlorobenzene and lindane onto humin samples, it is supposed that the nonlinearity can be a result of surface interactions, while the high sorption affinity is result of distribution of organic compounds in the amorphous aliphatic regions that offer an excellent environment for sorption.With the aim of further insight into the sorption mechanism, investigation of&nbsp;desorption kinetics of three chosen hydrophobic organic compounds,&nbsp;pentachlorobenzene, lindane and pentachloroaniline, in the presence of &nbsp;soild&nbsp;adsorbent XAD-4 macroporous ion-exchange resin was performed. On the basis of&nbsp;the results obtained for sediment sample and fraction &lt; 125 &micro;m at two equilibrium&nbsp;times (15 and 90 days) and for all selected organic compounds, it can be concluded&nbsp;that the assessment of the potential (bio)avialable fraction of organic compounds&nbsp;may be obtained by using simple method of desorption in the presence of XAD-4&nbsp;macroporous ion-exchange resin, performed in two ways: (1) by sediment&nbsp;extraction during 24 hours, when the desorbing fraction corresponds to the fraction&nbsp;of &nbsp;he compound that is found in the fast-desorbing domain of organic matter, or&nbsp;(2) by 6-hour extraction, when the desorbing fraction corresponds to one half of the&nbsp;fraction appearing in the fast-desorbing domain of the organic matter.