Yes / Reverse osmosis (RO) has become a common method for treating wastewater and removing several harmful organic compounds because of its relative ease of use and reduced costs. Chlorophenol is a toxic compound for humans and can readily be found in the wastewater of a wide range of industries. Previous research in this area of work has already provided promising results in respect of the performance of an individual spiral wound RO process for removing chlorophenol from wastewater, but the associated removal rates have stayed stubbornly low. The literature has so far confirmed that the efficiency of eliminating chlorophenol from wastewater using a pilot-scale of an individual spiral wound RO process is around 83 %, compared to 97 % for dimethylphenol. This paper explores the potential of an alternative configuration of two-stage/two-pass RO process for improving such low chlorophenol rejection rates via simulation and optimisation. The operational optimisation carried out is enhanced by constraining the total recovery rate to a realistic value by varying the system operating parameters according to the allowable limits of the process. The results indicate that the proposed configuration has the potential to increase the rejection of chlorophenol by 12.4 % while achieving 40 % total water recovery at an energy consumption of 1.949 kWh/m³.

Made available in DSpace on 2016-06-02T19:19:56Z (GMT). No. of bitstreams: 1 SILVA_Juliana_2012.pdf: 2696605 bytes, checksum: 1cfa39bd0ca5fd455b1f19f842575224 (MD5) Previous issue date: 2012-03-02 / Organochlorine compounds exhibit high toxicity, environmental persistence and tendency to bioaccumulate. This pollutant can spread through the air and water, affecting humans and the environment. In this context, this study aimed to develop an environmental sensor capable of detecting organochlorine compounds through nanostructured films fabricated from the layer-by-layer technique. The sensory units were composed of bilayers formed from Carbon Nanotubes (CNTs), alternated with Polyaniline (PAni). This study was divided into two main stages: the first was the fabrication and characterization of thin films and the second was the application of the film as sensor for environmental control of 2-chlorophenol. In the first stage individual films were fabricated with PAni and CNTs alternated with polyelectrolytes Poly(vinyl sulfonate) (PVS) and Poly(ethyleneimine) (PEI), respectively, and mixed film of CNTs/PAni. The films were characterized by UV-vis, FTIR and Raman spectroscopy, and by scanning electron microscopy (SEM). In the second stage sensory units were immersed in a liquid system containing 2-chlorophenol at different concentrations for characterization by means of electrochemical techniques of cyclic voltammetry and square wave voltammetry. The results of the film of CNTs/PAni showed good performance as electrochemical sensors for organochlorine compounds, since using the technique of square wave voltammetry detected the presence of 2-chlorophenol concentration from 2 ppm to the current intensity increased in about the film in individual CNTs. / Os compostos organoclorados apresentam alta toxicidade, persistência ambiental e mostram tendência à bioacumulação, podendo se propagar por meio do ar e da água afetando o homem e o meio ambiente. Neste contexto, este estudo visou o desenvolvimento de um sensor ambiental capaz de detectar compostos organoclorados através de filmes nanoestruturados fabricados a partir da técnica de automontagem (do inglês, Layer-by-Layer, LbL). As unidades sensoriais foram constituídas por bicamadas formadas de Nanotubos de Carbono (CNTs), intercalados com Polianilina (PAni). Essa dissertação foi dividida em duas principais etapas; a primeira na fabricação e caracterização de filmes finos e a segunda na aplicação do filme como unidade sensorial para controle ambiental de 2- clorofenol. Na primeira etapa foram fabricados filmes individuais de PAni e CNTs alternados com polieletrólitos Poli(vinil sulfonato de sódio) (PVS) e Poli(etilenoimina) (PEI), respectivamente, e o filme misto de CNTs/PAni. Os filmes foram caracterizados por medidas espectroscópicas de UV-vis, FTIR e Raman, e microscopia eletrônica de varredura (do inglês, Scanning Electron Microscopy, SEM). Na segunda etapa as unidades sensoriais foram imersas em um sistema líquido contendo 2- clorofenol em diferentes concentrações para caracterização por meio de técnicas eletroquímicas por voltametria cíclica e voltametria de onda quadrada. Os resultados do filme misto de CNTs/PAni mostraram bom desempenho como sensores eletroquímicos para compostos organoclorados, uma vez que através da técnica de voltametria de onda quadrada detectou a presença de 2-clorofenol na concentração a partir de 2 ppm com intensidade de corrente aumentada em relação ao filme individual dos CNTs.

Orientador: Gustavo Rocha de Castro / Banca: Raquel Fernandes Pupo Nogueira / Banca: Marcelo Organachi Orlandi / Banca: Katia Jorge Ciuffi / Banca: Silvana Ruella de Oliveira / Resumo: A contaminação de corpos d'água e águas subterrâneas por substâncias tóxicas ocasiona a redução da qualidade da água e até mesmo sua inapropriação para consumo. Atualmente as técnicas convencionais de tratamento de águas e resíduos aquosos não são capazes de descontaminá-los totalmente, pois substâncias recalcitrantes e substâncias parcialmente removidas/degradadas - como alguns clorofenóis (CPs) e substâncias desreguladoras endócrinas (SDEs) - permanecem na água mesmo após submetida aos tratamentos convencionais, reforçando a necessidade do desenvolvimento de procedimentos mais completos, sustentáveis e que também sejam economicamente viáveis. A exemplo, a fotocatálise heterogênea utilizando materiais semicondutores ativados pela radiação UV para produção, principalmente, de radicais hidroxilos pode ser aplicada para se degradar contaminantes em meio aquoso, sendo o óxido de titânio o material mais empregado devido àelevada atividade, baixo custo, estabilidade, disponibilidade e propriedades químicas, físicas e biológicas adequadas. Apesar de diversas vantagens associadas ao seu uso em fotocatálise heterogênea, sua aplicação na forma de suspensões (a fim de fazer melhor proveito da área superficial das partículas) ainda é restrita devido principalmente a dificuldades de separação/remoção destas após o processo de degradação. Neste trabalho, fotocatalisadores híbridos a base de titânia foram produzidos para realizar fotocatálise heterogênea de compostos orgânicos em meio aquo... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The contamination of waters and groundwaters by toxic substances reduces the quality of water and can even make it inadequate for consumption. Currently, the conventional techniques for treatment of waters and wastewaters are not able to completely decontaminate them. This is attributed to the presence of partially removed/degraded andrecalcitrant substances such as chlorophenols (CPs) and endocrine-disrupting chemicals (EDCs), since they persist in water even after the conventional treatment. This emphasizes the need for the development of more complete and sustainable processes that are also economically viable. For instance, heterogeneous photocatalysis utilizing UV-activated semiconductors for the production, mainly, of hydroxyl radicals is applied in the degradation of contaminants in aqueous medium. In this aspect, titanium oxide is the most used material in virtue of its high activity, low cost, stability, availability and suitable chemical, physical and biological properties. Despite so many advantages for the application of titanium oxide in heterogeneous photocatalysis, its application as slurries (to make better use of the surface area of particles) is still restrained by drawbacks related to separation/extraction steps. In this work, titania-based photocatalist hybrids were produced to perform heterogeneous photocatalysis of organic compounds in aqueous medium.As an alternative to implement particle separation from slurries, titania and mesoporous silica were depo... (Complete abstract click electronic access below) / Doutor

The aim of this study was to analyze number of incorporated T-DNA harbouring pmi and nptII transgenes and expression of the pmi gene in tomato transformants using Southern blot and Northern blot methods. The presence of a functional PMI protein was assesed using PMI-assay with Chlorophenol red dye. Mannose selection of tomato seeds was established and segregation patterns in T1 progeny were studied.

Submitted by Alexandre de Oliveira Jorgetto null (xjorgetto@gmail.com) on 2018-04-05T18:45:17Z No. of bitstreams: 1 Tese de doutorado - Alexandre de Oliveira Jorgetto.pdf: 5509260 bytes, checksum: b27fbb220e5624b1c0b2901186014558 (MD5) / Approved for entry into archive by Ana Carolina Gonçalves Bet null (abet@iq.unesp.br) on 2018-04-10T17:28:25Z (GMT) No. of bitstreams: 1 jorgetto_ao_dr_araiq_int.pdf: 5485342 bytes, checksum: 3cacde59176e43fc4144aff7336a05e9 (MD5) / Made available in DSpace on 2018-04-10T17:28:25Z (GMT). No. of bitstreams: 1 jorgetto_ao_dr_araiq_int.pdf: 5485342 bytes, checksum: 3cacde59176e43fc4144aff7336a05e9 (MD5) Previous issue date: 2018-03-09 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A contaminação de corpos d’água e águas subterrâneas por substâncias tóxicas ocasiona a redução da qualidade da água e até mesmo sua inapropriação para consumo. Atualmente as técnicas convencionais de tratamento de águas e resíduos aquosos não são capazes de descontaminá-los totalmente, pois substâncias recalcitrantes e substâncias parcialmente removidas/degradadas – como alguns clorofenóis (CPs) e substâncias desreguladoras endócrinas (SDEs) – permanecem na água mesmo após submetida aos tratamentos convencionais, reforçando a necessidade do desenvolvimento de procedimentos mais completos, sustentáveis e que também sejam economicamente viáveis. A exemplo, a fotocatálise heterogênea utilizando materiais semicondutores ativados pela radiação UV para produção, principalmente, de radicais hidroxilos pode ser aplicada para se degradar contaminantes em meio aquoso, sendo o óxido de titânio o material mais empregado devido àelevada atividade, baixo custo, estabilidade, disponibilidade e propriedades químicas, físicas e biológicas adequadas. Apesar de diversas vantagens associadas ao seu uso em fotocatálise heterogênea, sua aplicação na forma de suspensões (a fim de fazer melhor proveito da área superficial das partículas) ainda é restrita devido principalmente a dificuldades de separação/remoção destas após o processo de degradação. Neste trabalho, fotocatalisadores híbridos a base de titânia foram produzidos para realizar fotocatálise heterogênea de compostos orgânicos em meio aquoso. Como abordagem alternativa para implementação da separação de suspensões, realizou-se a deposição de sílica mesoporosa e titânia sobre núcleos de magnetita, sendo a magnetita responsável por possibilitar a separação magnética do material híbridode suspensões, enquanto que a sílica mesoporosa incrementaria a atividade da titânia por meio do aumento de sua área superficial. No caso do recobrimento por titânia, uma nova rota por meio de ebulição de etanol foi desenvolvida. Análises de difração de raios X indicaram que o recobrimento de sílica preveniu a conversão dos núcleos de magnetita à hematita após calcinação. Foi notado também a formação da fase anatase de titânia nos materiais híbridos para composições de titânia iguais ou maiores que 43 % em massa. Análises de espectroscopia de infravermelho reforçaram a presença de titânia juntamente à sílica, e também apontou para um limite de deposição para a titânia, que foi posteriormente verificado também por espectrofotometria de fluorescência de raios X. Através de microscopia eletrônica de varredura, observou-se a formação e crescimento da fase anatase sobre partículas de sílica e magnetita para composições de 53 % de titânia ou maiores, e análises de espectroscopia de energia dispersiva de raios X demonstraram os elementos Si e Ti se encontrarem bem-distribuídos ao redor das partículas de magnetita, sílica e titânia. O material híbrido produzido apresentou estrutura mesoporosa como o da sílica MCM-41, no entanto de área superficial específica menor, atingindo em torno de 248 m2 g-1. Análises de ressonância magnética nuclear de 29Si indicaram haver ligação química entre as fases sólidas de sílica e titânia. Experimentos de fotodegradação demonstraram que os híbridos de magnetita, sílica e titânia consistem de adsorventes ineficientes de 4-clorofenol. A atividade fotocatalítica destes materiais apresentou relação com o crescimento da textura de titânia, sendo os materiais fotoativos aqueles com composições de 53 % ou maiores. Cinéticas de degradação de ordem zero foram observadas para todos os materiais. Os materiais fotoativos também se demonstraram indiferentes ao pH do meio, com eficiências similares em pH 3,0 e 7,2. Ao se comparar as eficiências dos materiais híbridos, em termos de suas taxas iniciais de degradação, com as de materiais comerciais Hombikat 100 UV e Aeroxide® TiO2 P25 estabeleceu-se que a ordem decrescente de eficiência sob concentrações de catalisador otimizadas foi Aeroxide® TiO2 P25 > Hombikat 100 UV >híbrido de sílica e titânia >híbrido de magnetita, sílica e titânia. Concluiu-se dos experimentos de degradação que a incorporação de sílica e magnetita aos fotocatalisadores de titânia compromete a eficiência degradativa destes; em contrapartida, no caso dos materiais contendo núcleos de magnetita, sua recuperação magnética pode consistir de uma propriedade compensatória em termos de aplicação. A fim de se incrementar a atividade fotocatalítica dos materiais, estes foram sujeitos a etapas de modificação superficial por meio da incorporação de ácido rubeânico (AR) por silanização ou adsorção direta e/ou também por complexação de íons Fe3+ em meio aquoso, com a finalidade de se sensitizar os fotocatalisadores. A imobilização do AR por meio de silanização demonstrou-se mais eficiente, enquanto sua dessorção foi verificada para o material modificado por adsorção direta. No caso dos materiais modificados com Fe3+, constatou-se que a complexação destes íons sobre os materiais híbridos implicou na redução da fotoatividade destes, enquanto nenhum efeito foi notado em pH 6 para a fotoatividade de Hombikat 100 UV modificado. Mais experimentos seriam necessários para se determinar as taxas de degradação iniciais dos materiais estudados. Nos experimentos sob luz visível apenas Hombikat 100 UV e sua respectiva versão modificada apresentaram atividade. Ao se aplicar o material Hombikat 100 UV modificado com Fe3+ em pH 3,0, notou-se evidência de aumento de eficiência sob iluminação UV. / The contamination of waters and groundwaters by toxic substances reduces the quality of water and can even make it inadequate for consumption. Currently, the conventional techniques for treatment of waters and wastewaters are not able to completely decontaminate them. This is attributed to the presence of partially removed/degraded andrecalcitrant substances such as chlorophenols (CPs) and endocrine-disrupting chemicals (EDCs), since they persist in water even after the conventional treatment. This emphasizes the need for the development of more complete and sustainable processes that are also economically viable. For instance, heterogeneous photocatalysis utilizing UV-activated semiconductors for the production, mainly, of hydroxyl radicals is applied in the degradation of contaminants in aqueous medium. In this aspect, titanium oxide is the most used material in virtue of its high activity, low cost, stability, availability and suitable chemical, physical and biological properties. Despite so many advantages for the application of titanium oxide in heterogeneous photocatalysis, its application as slurries (to make better use of the surface area of particles) is still restrained by drawbacks related to separation/extraction steps. In this work, titania-based photocatalist hybrids were produced to perform heterogeneous photocatalysis of organic compounds in aqueous medium.As an alternative to implement particle separation from slurries, titania and mesoporous silica were deposited on the surface of magnetite cores. The incorporation of magnetite to the hybrid aimed to enable its magnetic separation from slurries whereas the incorporation of silica had the purpose of incrementing its activity by increasing the surface area of the hybrid material. A new route has been developed to perform the titania coating, which was based on the boiling of ethanolic medium. X-ray diffraction analyses indicated that the silica layer prevented phase conversion of magnetite cores to hematite after calcination. The formation of titania anatase phase was also observed for the hybrid materials for the mass composition of 43 % or greater. Infrared spectroscopy supported the presence of titania along with silica, and also pointed to a deposition limit for the titania layer that was also verified posteriorly through x-ray fluorescence spectrophotometry. Scanning electron microscopy enabled the observation of the formation and growth of anatase phase over magnetite-silica particles for compositions of 53 % or greater. Energy-dispersive x-ray spectroscopy demonstrated that Si and Ti were well- distributed over the magnetite-silica-titania particles. The hybrid material presented mesoporous structure likewise MCM-41, but with a smaller specific surface area of approximately 248 m2 g 1.29Si nuclear magnetic resonance provided evidence that silica and titania phases were chemically bonded. Photodegradation experiments demonstrated that magnetite-silica-titania hybrids are inefficient 4-chlorophenol adsorbents. The photocatalytic activity of the hybrids demonstrated to have relation with the growth of the titania texture, being the photoactive materials those with mass compositions of 53 % or greater. The kinetic behavior of the materials was found to have zero order and was pH-independent, having similar performances at pH 3.0 and 7.2. As the efficiencies of the hybrids are compared with those of commercial materials Hombikat 100 UV and Aeroxide® TiO2 P25, the decreasing order of efficiency could be obtained as Aeroxide® TiO2 P25 > Hombikat 100 UV >silica-titania hybrid > magnetite-silica-titania hybrid. Degradation experiments allowed to conclude that the incorporation of silica and magnetite to the titania photocatalists compromise their efficiencies; on the other hand, in the case of the materials containing magnetite cores, the possibility of magnetic retrieval may consist of a compensatory property with regard to practical application. To increment the photocatalytic activity of the materials, they underwent surface modification steps to have immobilized rubeanic acid (RA) either through sinalization or through direct adsorption. The complexation of Fe3+ to the surface of the hybrids was also tested in combination with rubeanic acid or without it to perform the sensitization of the photocatalysts. The immobilization of RA via silanization demonstrated to be more efficient, whereas its desorption could be verified for the material modified with RA by direct adsorption. In the case of hybrid materials modified with Fe3+ ions, the complexation of the ions led to a decay in their performance whereas no effect was observed at pH 6 for the material Hombikat 100 UV modified with Fe3+.More experiments are necessary to determine the initial degradation rates of the studied materials. In the experiments under visible light, only Hombikat 100 UV and its modified version presented photoactivity. When Fe3+-modified Hombikat 100 UV was tested at pH 3.0, evidence of increase in activity was noted under UV illumination. / Fapesp 2013/22955-2 e 2015/05224-0

No description available.

Uncertainty is pervasive in risk assessment. In ecotoxicological risk assessments, it arises from such sources as a lack of data, the simplification and abstraction of complex situations, and ambiguities in assessment endpoints (Burgman 2005; Suter 1993). When evaluating and managing risks, uncertainty needs to be explicitly considered in order to avoid erroneous decisions and to be able to make statements about the confidence that we can place in risk estimates. Although informative, previous approaches to dealing with uncertainty in ecotoxicological modelling have been found to be limited, inconsistent and often based on assumptions that may be false (Ferson & Ginzburg 1996; Suter 1998; Suter et al. 2002; van der Hoeven 2004; van Straalen 2002a; Verdonck et al. 2003a). In this thesis a Generalised Linear Modelling approach is proposed as an alternative, congruous framework for the analysis and prediction of a wide range of ecotoxicological effects. This approach was used to investigate the results of toxicity experiments on the effect of 2,4-Dichlorophenoxyacetic Acid (2,4-D) formulations and 4-Chlorophenol (4-CP, an associated breakdown product) on Daphnia carinata. Differences between frequentist Maximum Likelihood (ML) and Bayesian Markov-Chain Monte-Carlo (MCMC) approaches to statistical reasoning and model estimation were also investigated. These approaches are inferentially disparate and place different emphasis on aleatory and epistemic uncertainty (O'Hagan 2004). Bayesian MCMC and Probability Bounds Analysis methods for propagating uncertainty in risk models are also compared for the first time. For simple models, Bayesian and frequentist approaches to Generalised Linear Model (GLM) estimation were found to produce very similar results when non-informative prior distributions were used for the Bayesian models. Potency estimates and regression parameters were found to be similar for identical models, signifying that Bayesian MCMC techniques are at least a suitable and objective replacement for frequentist ML for the analysis of exposureresponse data. Applications of these techniques demonstrated that Amicide formulations of 2,4-D are more toxic to Daphnia than their unformulated, Technical Acid parent. Different results were obtained from Bayesian MCMC and ML methods when more complex models and data structures were considered. In the analysis of 4-CP toxicity, the treatment of 2 different factors as fixed or random in standard and Mixed-Effect models was found to affect variance estimates to the degree that different conclusions would be drawn from the same model, fit to the same data. Associated discrepancies in the treatment of overdispersion between ML and Bayesian MCMC analyses were also found to affect results. Bayesian MCMC techniques were found to be superior to the ML ones employed for the analysis of complex models because they enabled the correct formulation of hierarchical (nested) datastructures within a binomial logistic GLM. Application of these techniques to the analysis of results from 4-CP toxicity testing on two strains of Daphnia carinata found that between-experiment variability was greater than that within-experiments or between-strains. Perhaps surprisingly, this indicated that long-term laboratory culture had not significantly affected the sensitivity of one strain when compared to cultures of another strain that had recently been established from field populations. The results from this analysis highlighted the need for repetition of experiments, proper model formulation in complex analyses and careful consideration of the effects of pooling data on characterising variability and uncertainty. The GLM framework was used to develop three dimensional surface models of the effects of different length pulse exposures, and subsequent delayed toxicity, of 4-CP on Daphnia. These models described the relationship between exposure duration and intensity (concentration) on toxicity, and were constructed for both pulse and delayed effects. Statistical analysis of these models found that significant delayed effects occurred following the full range of pulse exposure durations, and that both exposure duration and intensity interacted significantly and concurrently with the delayed effect. These results indicated that failure to consider delayed toxicity could lead to significant underestimation of the effects of pulse exposure, and therefore increase uncertainty in risk assessments. A number of new approaches to modelling ecotoxicological risk and to propagating uncertainty were also developed and applied in this thesis. In the first of these, a method for describing and propagating uncertainty in conventional Species Sensitivity Distribution (SSD) models was described. This utilised Probability Bounds Analysis to construct a nonparametric 'probability box' on an SSD based on EC05 estimates and their confidence intervals. Predictions from this uncertain SSD and the confidence interval extrapolation methods described by Aldenberg and colleagues (2000; 2002a) were compared. It was found that the extrapolation techniques underestimated the width of uncertainty (confidence) intervals by 63% and the upper bound by 65%, when compared to the Probability Bounds (P3 Bounds) approach, which was based on actual confidence estimates derived from the original data. An alternative approach to formulating ecotoxicological risk modelling was also proposed and was based on a Binomial GLM. In this formulation, the model is first fit to the available data in order to derive mean and uncertainty estimates for the parameters. This 'uncertain' GLM model is then used to predict the risk of effect from possible or observed exposure distributions. This risk is described as a whole distribution, with a central tendency and uncertainty bounds derived from the original data and the exposure distribution (if this is also 'uncertain'). Bayesian and P-Bounds approaches to propagating uncertainty in this model were compared using an example of the risk of exposure to a hypothetical (uncertain) distribution of 4-CP for the two Daphnia strains studied. This comparison found that the Bayesian and P-Bounds approaches produced very similar mean and uncertainty estimates, with the P-bounds intervals always being wider than the Bayesian ones. This difference is due to the different methods for dealing with dependencies between model parameters by the two approaches, and is confirmation that the P-bounds approach is better suited to situations where data and knowledge are scarce. The advantages of the Bayesian risk assessment and uncertainty propagation method developed are that it allows calculation of the likelihood of any effect occurring, not just the (probability)bounds, and that the same software (WinBugs) and model construction may be used to fit regression models and predict risks simultaneously. The GLM risk modelling approaches developed here are able to explain a wide range of response shapes (including hormesis) and underlying (non-normal) distributions, and do not involve expression of the exposure-response as a probability distribution, hence solving a number of problems found with previous formulations of ecotoxicological risk. The approaches developed can also be easily extended to describe communities, include modifying factors, mixed-effects, population growth, carrying capacity and a range of other variables of interest in ecotoxicological risk assessments. While the lack of data on the toxicological effects of chemicals is the most significant source of uncertainty in ecotoxicological risk assessments today, methods such as those described here can assist by quantifying that uncertainty so that it can be communicated to stakeholders and decision makers. As new information becomes available, these techniques can be used to develop more complex models that will help to bridge the gap between the bioassay and the ecosystem.

Mixtures of chlorinated organic pollutants can be found in the soils at chlorophenol-contaminated sawmill, including (inter alia) polychlorinated phenols (CPs), phenoxyphenols (PCPPs), diphenyl ethers (PCDEs), dibenzofurans (PCDFs) and dioxins (PCDDs). These hydrophobic compounds have low water solubility and hence low mobility as truly dissolved compounds. However, they may migrate through the soil at significant rates via co-transport with dissolved organic matter (DOM) and colloids of fine, waterborne particulate matter. In the work underlying this thesis the distribution of chlorinated hydrophobic pollutants between these two mobile fractions in soil samples from five sawmill sites was studied Soils at five sites at which CPs were formerly used were characterized, and found to have complex profiles of chlorinated hydrophobic pollutants. CPs, PCPPs, PCDEs and PCDD/Fs were present at up to ppm-levels. Furthermore, the relative proportions of the pollutants differed from their relative proportions in the preservatives used at the sites, indicating that they have been transported from, and/or degraded in, the soil at different rates. These organic pollutants have low water solubility and strong affinity for soil organic matter (SOM). The importance of SOM for the fate of CPs, PCPPs, PCDEs, PCDFs and PCDDs in soil was investigated by examining the distribution of compounds between the mobile DOM and the immobile particulate organic matter (POM). The partitioning of CPs between DOM and POM was found to be approximately equal. However, the relative strength of association with POM of groups of chlorinated organic pollutants was positively correlated with their hydrophobicity, and thus increased in the order CP < PCPP < PCDE < PCDF < PCDD. Despite the weak association of PCDD/Fs with DOM our investigations found that considerable concentrations of these pollutants were bound to mobile fractions (DOM and colloids, >0.2 µm) in both a groundwater analysis and a leaching test. CPs and PCPP were present at up to ppm- and ppb-levels, respectively, and PCDEs and PCDD/Fs at up to ppt-levels. The importance of transport in association with the mobile fraction (DOM and colloids) increased with increasing hydrophobicity e.g. PCDDs were almost entirely associated with fine particulate matter, while CPs were largely found in the water phase and only minor proportions were associated with colloids.

Ce travail, sur la dépollution de l’eau par OVHC sur charbon actif (CA), étudie l'interaction oxydation - adsorption : comment l'oxydation sur charbon de produits aromatiques modifie ses propriétés et en particulier sa capacité d'adsorption et d'oxydation (désactivation). Divers charbons commerciaux, mais aussi issus de boues activées, ont été caractérisés avant et après oxydation : propriétés texturales, composition élémentaire (CHNSO), fonctions de surface, pH au point de charge nulle et allure des courbes ATG. Seule leur teneur en cendres semble différer notablement. Les charbons actifs de boues ont une surface spécifique bien moindre (de 90 à 265 m².g-1) et un taux de cendres supérieur à 50% qui en font de moins bons adsorbants. Cependant la présence de métal, notamment le fer, a un effet positif sur l'oxydation catalytique. L'étude comparative en oxydation catalytique de 4 CA commerciaux en grains montre une désactivation intense (qui augmente avec la concentration de polluant) sur les 3-4 premières utilisations, puis une stabilisation. Le charbon résultant est nettement moins adsorbant. Les CA S23 et F22 ainsi stabilisés ont ensuite été utilisés pour déterminer la cinétique d'oxydation catalytique apparente et intrinsèque du phénol, grâce à un modèle incluant la diffusion. La comparaison de l'OVHC de 4 polluants aromatiques seuls et en divers mélanges synthétiques met en évidence des effets de mélange significatifs: les polluants les plus réfractaires en oxydation catalytique se dégradent beaucoup plus vite en mélange (ex 4NP) et inversement, les polluants les plus oxydés, lorsqu'ils sont seuls en solution, voient leur cinétique diminuer lorsqu'ils sont mélangés aux autres polluants (ex phénol, 4chlorophénol). Le mélange tend donc à uniformiser les comportements particuliers. Enfin, les essais de faisabilité du procédé de régénération oxydante AD-OX ont été effectués sur des effluents industriels. La régénération du charbon actif comme adsorbant est moins limitée qu'avec des mélanges de phénols substitués. / This work, on water treatment by catalytic Wet Air Oxidation (CWAO) using activated carbon (AC), aimed to study the interaction between oxidation-adsorption phenomena: how the oxidation of aromatic compounds on AC can modify its properties and specially its adsorption and oxidation characteristics (deactivation). Various commercials AC, and AC produced from activated sludge, have been characterized before and after oxidation by according methods such as textural characterization, elemental analysis (CHNSO), functional groups on carbon surfaces analysis, pH of the point of zero charge (pHpzc) analysis and thermogravimetric analysis (TGA); however, only their ash level was significantly different. In addition, the sludge based AC (SBAC) have a specific surface range of 90 to 265 m².g-1, which is lower than commercial AC, and with an ash level over 50%. Consequently they are less good adsorbents. However, the presence of metal, e.g. iron, has a positive affect on catalytic oxidation. The comparative study of catalytic oxidation with 4 commercial AC, show a severe deactivation (which increase with the pollutant concentration) on the first 3-4 utilizations before stabilization. The residual AC is clearly poor adsorbent. After stabilization, 2 commercials AC, only S23 and F22 CA, were studied on catalytic oxidation of phenol in term of apparent and intrinsic kinetics with including the diffusion effect in the model. The CWAO of 4 pure aromatic pollutants, and their various synthetic mixtures, showed mixing effects significantly: the most oxidation catalytic refractory pollutants were degraded rapidly when they mixed (e.g. 4-nitrophenol) but the kinetic was slow down for the pure pollutant whereas, the most oxidised pollutants, for pure solution, have an oxidation kinetic slower than when they mixed with others pollutants (e.g. Phenol, 4-chlorophenol). Therefore, the mixture tends to standardize from the individual behaviour. In conclude, the feasibility study of the oxidative regeneration process (AD-OX) was performed on industrial waste water. The regeneration AC as adsorbent is less limited than with mixtures of substituted phenols.

M. Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology. / The presence of organic and inorganic pollutants in aqueous environments is one of the major challenges confronting man. It is therefore important to develop sensitive, versatile and cheap techniques for their detection. Arsenic (III), 2-chlorophenol (2-CP) and sulfamethoxazole (SMX) are priority pollutants that pose health threats to humans and animals. This study was thus aimed at exploring two promising carbon nanomaterials as electrode modifiers for the electrochemical sensing of arsenic (III), 2-CP and SMX in water. Glassy carbon electrode (GCE) was modified with a nanocomposite of carbon dots (CDs) and graphitic carbon nitride (g-C3N4) and used as a sensor for the analytes in aqueous media. The CDs was prepared by a facile one-pot hydrothermal method using pine cone as the carbon source; g-C3N4 and g-C3N4/CDs nanocomposite were prepared via the microwave irradiation heating method. CDs, g-C3N4 and g-C3N4/CDs were dropped-dried on the surface of bare GCE. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the prepared materials. GCE, g-C3N4/GCE, CDs/GCE and g-C3N4/CDs/GCE electrodes were electrochemically investigated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) using a ferrocyanide [Fe (CN) 6]3-/4- redox probe. The current and the reversibility of the redox probes were enhanced in the presence of modifiers. The electrochemical behavior of arsenic (III), 2-CP and SMX on different electrodes (GCE, CDs/GCE, g-C3N4/GCE and g-C3N4/CDs/GCE) were investigated by differential pulse voltammetry (DPV) under optimized conditions in a phosphate buffer solution (pH 7.6, 6 and 5 for 2-CP, As (III) and SMX respectively). The results demonstrated that the g-C3N4/CDs/GCE electrode significantly enhanced the oxidation peak current of all three analytes. The detection sensitivity of the analytes was greatly improved, suggesting that this new modified electrode has great potential in the determination of trace level of arsenic (III), 2-CP and SMX in water. The oxidation peak currents displayed a linear relationship to concentrations for 2-CP (0.5 - 2.5 μM, R2=0.958, n=5), arsenic (III) (2 - 10 μM R2=0.978, n=5) and SMX (0.3 - 1.3 μM R2=0.9906, n=5). The detection limits of 0.62 μM, 1.64 μM and 0.10 μM were obtained for 2-CP, arsenic and SMX, respectively. Phenol and 4-chloro-3-methyl-phenol were found to interfere with the detection of 2-CP, while, Cu2+, Zn2+, Pb2+ and Cd2+ were the only significant ions that interfered with the electrochemical detection of arsenic (III). EDTA was used as a ligand to mask the interference effects of copper, cadmium, lead and zinc on arsenic sensing. The modified electrode (g-C3N4/CDs/GCE) was used to determine arsenic, 2-CP and SMX in spiked tap and effluent water samples by the standard addition method and the results showed percentage recoveries varying from 93-118% for 2-CP, 98-100% for arsenic and 80-105% for SMX. The outcomes of this study established that the nanocomposite material represents an easy and sensitive sensing platform for the monitoring of arsenic (III), 2-CP and SMX in aqueous media.