O uso de técnicas espectroscópicas para o estudo de questões ambientais é uma área de pesquisa que vem experimentando importante desenvolvimento em tempos recentes. Essas técnicas abrangem métodos espectroscópicos intensificados, que proporcionam grande sensibilidade e seletividade para a detecção de espécies químicas em baixas concentrações. Nesta dissertação, propomos a introdução de uma nova metodologia aplicada ao estudo da fotodegradação de moléculas de interesse ambiental. Utilizamos técnicas de espectroscopia Raman intensificada pela superfície (SERS) para a análise dos processos de fotodegradação de azo-corantes mediados por dióxido de titânio. Nosso primeiro passo para o desenvolvimento dessa metodologia foi realizar um estudo comparativo acerca de diferentes métodos para preparação de um substrato SERS-ativo - sobre cuja superfície viríamos a proceder a fotodegradação de corantes e simultaneamente o estudo espectroscópico desse processo. A dificuldade na preparação do substrato reside no fato de que é necessário produzir uma superfície simultaneamente fotocatalítica (pela presença do semicondutor TiO2) e com atividade SERS (pela presença de partículas de Ag nanoestruturadas). Assim, três diferentes métodos para a preparação do substrato foram estudados, buscando obter atividade SERS aliada à reprodutibilidade. Escolhido o método mais satisfatório, utilizamos o substrato para realizar estudos SERS dos processos de fotodegradação de dois corantes: vermelho do Congo e verde de Janus. Considerando que a degradação fotocatalítica pode envolver oxidação e redução das moléculas, foi realizado também o estudo espectroeletroquímico dos dois corantes, buscando correlações que ajudassem a esclarecer as transformações envolvidas nas etapas iniciais da fotodegradação dessas substâncias. Nossos estudos revelaram que as primeiras etapas dos processos de fotodegradação dos dois corantes seguem mecanismos diferentes: enquanto no caso do vermelho do Congo há evidências de oxidação, no caso do verde de Janus as evidências apontam para um processo de redução. A combinação de dados da fotodegradação de corantes com seu estudo via eletroquímica - utilizando técnicas de espectroscopia intensificada para a identificação e caracterização de produtos - mostrou-se bastante promissora, no sentido de oferecer informações relevantes sobre os complexos mecanismos envolvidos nos processos de fotodegradação. / The use of spectroscopic techniques for the study of environmental questions is a research area has been experiencing important developments in recent years. These techniques embrace intensified spectroscopic methods, which offer great sensibility and selectivity for the detection of chemical species in low concentrations. In this work, we propose the introduction of a new methodology to be applied to the study of photodegradation of environmentally relevant molecules. We employed surface-enhanced Raman spectroscopy to the analysis of photodegradation of azo-dyes mediated by titanium dioxide. First, we performed a comparative study concerning the different methods for the preparation of SERS-active substrate, onto which we would carry out simultaneously the photodegradation of dyes and the spectroscopic study of the process. The difficulty in the preparation of such substrates resides in the fact that it is necessary to produce a surface which is all together photocatalytic (by the presence of the semiconducting TiO2) and SERS-active (by the presence of nanostructured silver). In this context, three different preparation methods were investigated, with the purpose of achieving good SERS activity and reproducibility. The optimized SERS-active substrate was employed to study the photodegradation of two azo-dyes: Congo red and Janus green. Considering that the photocatalitic degradation process might involve either the oxidation or the reduction of molecules, the spectroelectrochemical study of both dyes was also performed, in order to in order to search for important correlations that would help to clarify the transformations involved in the initial steps of the photochemical decomposition of these substances. The obtained results revealed that the first steps of the degradation processes of both dyes followed different routes: whereas for Congo red there are evidences of an oxidation process, for Janus green the evidences point to a reduction mechanism. The combination of the data relative to the photochemical behavior of the dyes and their electrochemical study - using enhanced spectroscopic techniques for identification and characterization of products - has proven to be very promising, in the sense of offering relevant information with respect to the complex mechanisms that are involved in photodegradation processes.

O uso de técnicas espectroscópicas para o estudo de questões ambientais é uma área de pesquisa que vem experimentando importante desenvolvimento em tempos recentes. Essas técnicas abrangem métodos espectroscópicos intensificados, que proporcionam grande sensibilidade e seletividade para a detecção de espécies químicas em baixas concentrações. Nesta dissertação, propomos a introdução de uma nova metodologia aplicada ao estudo da fotodegradação de moléculas de interesse ambiental. Utilizamos técnicas de espectroscopia Raman intensificada pela superfície (SERS) para a análise dos processos de fotodegradação de azo-corantes mediados por dióxido de titânio. Nosso primeiro passo para o desenvolvimento dessa metodologia foi realizar um estudo comparativo acerca de diferentes métodos para preparação de um substrato SERS-ativo - sobre cuja superfície viríamos a proceder a fotodegradação de corantes e simultaneamente o estudo espectroscópico desse processo. A dificuldade na preparação do substrato reside no fato de que é necessário produzir uma superfície simultaneamente fotocatalítica (pela presença do semicondutor TiO2) e com atividade SERS (pela presença de partículas de Ag nanoestruturadas). Assim, três diferentes métodos para a preparação do substrato foram estudados, buscando obter atividade SERS aliada à reprodutibilidade. Escolhido o método mais satisfatório, utilizamos o substrato para realizar estudos SERS dos processos de fotodegradação de dois corantes: vermelho do Congo e verde de Janus. Considerando que a degradação fotocatalítica pode envolver oxidação e redução das moléculas, foi realizado também o estudo espectroeletroquímico dos dois corantes, buscando correlações que ajudassem a esclarecer as transformações envolvidas nas etapas iniciais da fotodegradação dessas substâncias. Nossos estudos revelaram que as primeiras etapas dos processos de fotodegradação dos dois corantes seguem mecanismos diferentes: enquanto no caso do vermelho do Congo há evidências de oxidação, no caso do verde de Janus as evidências apontam para um processo de redução. A combinação de dados da fotodegradação de corantes com seu estudo via eletroquímica - utilizando técnicas de espectroscopia intensificada para a identificação e caracterização de produtos - mostrou-se bastante promissora, no sentido de oferecer informações relevantes sobre os complexos mecanismos envolvidos nos processos de fotodegradação. / The use of spectroscopic techniques for the study of environmental questions is a research area has been experiencing important developments in recent years. These techniques embrace intensified spectroscopic methods, which offer great sensibility and selectivity for the detection of chemical species in low concentrations. In this work, we propose the introduction of a new methodology to be applied to the study of photodegradation of environmentally relevant molecules. We employed surface-enhanced Raman spectroscopy to the analysis of photodegradation of azo-dyes mediated by titanium dioxide. First, we performed a comparative study concerning the different methods for the preparation of SERS-active substrate, onto which we would carry out simultaneously the photodegradation of dyes and the spectroscopic study of the process. The difficulty in the preparation of such substrates resides in the fact that it is necessary to produce a surface which is all together photocatalytic (by the presence of the semiconducting TiO2) and SERS-active (by the presence of nanostructured silver). In this context, three different preparation methods were investigated, with the purpose of achieving good SERS activity and reproducibility. The optimized SERS-active substrate was employed to study the photodegradation of two azo-dyes: Congo red and Janus green. Considering that the photocatalitic degradation process might involve either the oxidation or the reduction of molecules, the spectroelectrochemical study of both dyes was also performed, in order to in order to search for important correlations that would help to clarify the transformations involved in the initial steps of the photochemical decomposition of these substances. The obtained results revealed that the first steps of the degradation processes of both dyes followed different routes: whereas for Congo red there are evidences of an oxidation process, for Janus green the evidences point to a reduction mechanism. The combination of the data relative to the photochemical behavior of the dyes and their electrochemical study - using enhanced spectroscopic techniques for identification and characterization of products - has proven to be very promising, in the sense of offering relevant information with respect to the complex mechanisms that are involved in photodegradation processes.

No description available.

The compound p-(2-hydroxyethylsulfone) aniline was isolated from a reduced solution of a fiber-reactive azo dye. The identity and purity of this product was assessed through elemental composition analysis, high performance liquid chromatography (HPLC), gas chromatography/mass spectroscopy (GC/MS), and nuclear magnetic resonance spectroscopy (NMR). The toxicity of this purified compound was measured with Microtox and Daphnia pulex tests. Microtox tests were also performed on compounds with similar structures to p- (2-hydroxyethylsulfone) aniline. Wastewater samples containing textile dye wastes from a Publicly Owned Treatment Works (POTW) that treated textile dye wastes were monitored for the presence of p-(2-hydroxyethylsulfone) aniline using HPLC. Microtox testing was performed on these samples. Analytical tests confirmed the identity and purity of p-(2-hydroxyethylsulfone) aniline as the reduced product. Microtox tests revealed the concentration at which 50% of the light output was reduced (EC₅₀) after 5 minutes of exposure was 12.8 mg/L. Daphnia pulex testing yielded the concentration which was lethal to 50% of the tested organisms (LC₅₀) to be 113 mg/L. The 5-minute Microtox EC₅₀, values of aniline, sulfanilamide, 2-hydroxyethylsulfone, and 4-ethylaniline were 106.7, 8.15, >80, and 2.05 mg/L, respectively. The reduction product, p-(2-hydroxyethylsulfone)aniline, was not detected in textile-containing wastewater from the Martinsville POTW. The Microtox EC₅₀, for this wastewater, ranged from 6.05 to >75 mg/L. / Master of Science

The degradation of wool keratin under conditions relevant to those of wool dyeing was investigated using the techniques of gel permeation chromatography (GPC), ion exchange gel chromatography, and amino acid analysis. Physical testing of the treated and untreated wool was also carried out to determine the physical changes occurring, parameters used being percentage elongation at the break, and the breaking strain of the fibre. Samples of wool keratin were immersed in various aqueous solutions at 1000C for 24 hours and the filtered, aqueous, oxidised extracts were analysed* The solutions used varied only in the dye, or dye intermediate present in the treatment solution. All treatment baths contained 10% owf 1.02 x 10 -2 MSulphuric VI acid; 10%owf 7.04x 10 -3 MSodium sulphate VI ; A 100 :1 liquor ratio was used in each case. Some of the dye intermediates showed a marked catalytic effect, particularly in their effect on breaking strain, a decrease of 40% in some cases. The GPC profiles of the extracted proteins were examined in detail and compared against previous workers' results. An explanation of the behaviour of the dyes and intermediates was proposed. The amino acid composition data of the extracted and fractionated proteins were compared against various morphological components extracted by other workers, as was the total gelatin obtained from each treatment.

nÃo hà / A descarga de efluentes das indÃstrias tÃxteis para corpos aquosos Ã, correntemente, uma das maiores preocupaÃÃes dos ambientalistas em funÃÃo dos corantes sintÃticos usados para colorir os tecidos poluindo assim o ambiente. A aplicaÃÃo de tratamentos biolÃgicos, sobretudo com a utilizaÃÃo de bactÃrias, apresenta-se como um dos mais viÃveis economicamente, sendo um dos sistemas mais utilizados para descolorir efluentes coloridos. Neste sentido, estudos foram realizados testes para a remoÃÃo de cor dos corantes Remazol Brilliant Blue R, Orange G e Orange II utilizando cepas de Escherichia coli e de Aeromonas hydrophila, isoladas e em cultura mista. Primeiramente foi feito o isolamento das cepas bacterianas de trÃs ambientes diferentes. Em seguida, foram feitos testes para verificar qual concentraÃÃo do corante seria limite para o crescimento de cada microrganismo. AlÃm dos testes de descoloraÃÃo tambÃm foram monitorados outros parÃmetros como o pH, biomassa, remoÃÃo de DQO, proteÃnas totais e toxicidade dos metabÃlitos formados. A cepa Escherichia coli, isolada do ambiente marinho, foi capaz de descolorir concentraÃÃes de 2, 5 e 2 mg L-1, respectivamente, para os corante RBBR, Orange G e Orange II, enquanto que a cepa E. coli, isolada do efluente tÃxtil, descoloriu nas concentraÃÃes de 5, 0,5 e 5 mg L-1, respectivamente. A bactÃria Aeromonas hydrophila descoloriu respectivamente nas concentraÃÃes de 10, 5 e 5 mg L-1, enquanto que o consÃrcio das trÃs bactÃrias descoloriu na concentraÃÃo de 5 mg L-1 para os trÃs corantes testados individualmente. Nessas condiÃÃes de cultivo a diminuiÃÃo na taxa de DQO variou entre 45 e 69%, com a menor taxa observada no ensaio contendo A. hydrophila e o corante Orange II (45%) e a maior taxa de remoÃÃo no ensaio contendo o consÃrcio e o corante RBBR (69%). Bioensaios utilizando o microcrustÃceo Artemia salina mostraram que durante o processo de descoloraÃÃo foram produzidos metabÃlitos com caracterÃsticas recalcitrantes. Os resultados demonstram que as bactÃrias Escherichia coli e Aeromonas hydrophila apresentam potencial biotecnolÃgico na descoloraÃÃo de corantes tÃxteis, desde que sejam utilizadas baixas concentraÃÃes dos corantes / The discharge of effluents from textile industries for water bodies is currently a major concern for environmentalists as a function of synthetic dyes used to color fabrics thus polluting the environment. Biological treatments, especially with the use of bacteria, present themselves as the most economically viable and widely used to decolorize colored effluents. Thus, studies were conducted to test the color removal of dyes Remazol Brilliant Blue R, Orange G and Orange II using isolated and in mixed culture strains of Escherichia coli and Aeromonas hydrophila. Firstly, the isolation of bacterial strains from three different environments was made. Then, tests were performed to verify that the dye concentration would limit the growth of each microorganism. In addition to tests of decolorization, other parameters such as pH, biomass, COD removal, total protein and toxicity of metabolites were also monitored. The Escherichia coli strain isolated from the marine environment was able to decolorize concentrations of 2, 5 and 2 mg L-1, respectively, for the RBBR dye, Orange G and Orange II dyes, while the strain E. coli isolated from textile effluent, decolorized in concentrations of 5, 0.5 and 5 mg L-1, respectively. The bacteria Aeromonas hydrophila decolorized, respectively, at 10, 5 and 5 mg L-1, while the consortium of three bacteria decolorized at concentration of 5 mg L-1 for the three dyes tested individually. In these culture conditions the decrease in the rate of COD ranged from 45% to 69% with the lowest rate observed in the assay containing A. hydrophila and dye Orange II (45%) and the highest removal rate in the test containing the dye RBBR and the consortium (69%). Bioassays using Artemia salina showed that during the process of decolorization metabolites were produced with recalcitrant characteristics. The results show that the bacteria Escherichia coli and Aeromonas hydrophila have biotechnological potential in textile dyes, provided that they use low dye concentrations decolorizing

MENVSC / Department of Ecology and Resource Management / In this study, the efficacy of bentonite clay, pre-treated magnesite and their nanocomposite on the removal of Congo red dye from aqueous solution was explored. Batch experimental approach was a technique used to fulfil the goals of this study. A number of operational parameters were optimised, and they include effects of shaking time, adsorbent dosage, initial CR dye concentration, initial solution pH and temperature. Findings of the study revealed that the optimum conditions that are suitable for the removal of CR dye are 20 minutes, 0.5 g of dosage, 120 mg/L, 250 rpm, and pH = 7. This has achieved > 99% removal efficacy of CR dye for the nanocomposite and reduced it to below the South African National Standard (SANS) 241 water quality specifications. Furthermore, kinetic studies revealed that bentonite clay, pre-treated magnesite, and their nanocomposite fitted very well to pseudo-second-order kinetics than pseudo-first-order kinetics. The regression analysis was observed to be 1, 0.9, and 0.9 for bentonite clay, pre-treated magnesite, and their nanocomposite respectively. Adsorption isotherms indicated that CR removal by bentonite clay, pre-treated magnesite, and their nanocomposite fitted well to Langmuir adsorption isotherm than the Freundlich adsorption isotherm hence indicating mono-layer adsorption. Thermodynamic values for CR removal were observed to be: ΔH0 (kJ mol-1) = 43.86, 30.67, and 24.88 for bentonite clay, pre-treated magnesite, and their nanocomposite respectively. This indicates that the reaction is endothermic. The positive ΔS0 (kJ mol-1 K-1) values for bentonite clay and 25 °C for pre-treated magnesite confirms that there is an increase in the degree of randomness at solid/solution interface during the removal of CR ions from aqueous solution. The negative values of ΔG0 (kJ mol-1) for 40 – 70 °C on bentonite and the entire range for the nanocomposite suggest the spontaneity and feasibility of CR adsorption whereas the positive ΔG0 (kJ mol-1) for bentonite clay suggest a non-spontaneous nature of adsorption. As such, pre-treated magnesite/bentonite clay nanocomposite demonstrated superior adsorption capacity in relation to individual materials and other materials reported in literature. / NRF

The degradation of wool keratin under conditions relevant to those of wool dyeing was investigated using the techniques of gel permeation chromatography (GPC), ion exchange gel chromatography, and amino acid analysis. Physical testing of the treated and untreated wool was also carried out to determine the physical changes occurring, parameters used being percentage elongation at the break, and the breaking strain of the fibre. Samples of wool keratin were immersed in various aqueous solutions at 1000C for 24 hours and the filtered, aqueous, oxidised extracts were analysed* The solutions used varied only in the dye, or dye intermediate present in the treatment solution. All treatment baths contained 10% owf 1.02 x 10 -2 MSulphuric VI acid; 10%owf 7.04x 10 -3 MSodium sulphate VI ; A 100 :1 liquor ratio was used in each case. Some of the dye intermediates showed a marked catalytic effect, particularly in their effect on breaking strain, a decrease of 40% in some cases. The GPC profiles of the extracted proteins were examined in detail and compared against previous workers' results. An explanation of the behaviour of the dyes and intermediates was proposed. The amino acid composition data of the extracted and fractionated proteins were compared against various morphological components extracted by other workers, as was the total gelatin obtained from each treatment. / Science Research Council

In the past 30 years zero-valent iron (ZVI) has become an increasingly popular reducing agent technology for remediating environmental contaminants prone to chemical degradation. Azo dyes and chlorinated organic compounds (COCs) are two classes of such contaminants, both of which include toxic compounds with known carcinogenic potential. ZVI has been successfully applied to the surfaces of permeable reactive barriers, as well as grown into nanoscale particles (nZVI) and applied in-situ to chemically reduce these contaminants into more environmentally benign compounds. However, the reactivity of ZVI and nZVI in these technologies is limited by their finite supply of electrons for facilitating chemical reduction, and the tendency of nZVI particles to homo-aggregate in solution and form colloids with reduced surface area to volume ratio, and thus reduced reactivity. The goal of this project was to combine reactive nanoparticle and membrane technologies to create an electro-catalytic permeable reactive barrier that overcomes the weaknesses of nZVI for the enhanced electrochemical filtration of azo dyes in solution. Specifically, nZVI was successfully grown and stabilized in a network of functionalized carbon nanotubes (CNTs) and deposited into an electrically conductive thin film on the surface of a polymeric microfiltration support membrane. Under a cathodic applied voltage, this thin film facilitated the direct reduction of the methyl orange (MO) azo dye in solution, and regenerated nZVI reactivity for enhanced electro-catalytic operation. The electro-catalytic performance of these nZVI-CNT membrane surface composites to remove MO was validated, modelled, and optimized in a batch system, as well as tested in a dead-end continuous flow cell system. In the batch experiments, systems with nZVI and a -2 V applied potential demonstrated synergistic enhancement of MO removal, which indicated the regeneration of nZVI reactivity and allowed for the complete removal of 0.25 mM MO batches within 2-3 hours. Partial least squares regression (PLSR) modelling was used to determine the impact of each experimental parameter in the batch system and provided the means for an optimization leading to maximized MO removal. Finally, tests in a continuous system yielded rates of MO removal 1.6 times greater than those of the batch system in a single pass, and demonstrated ~87% molar removal of MO at fluxes of approximately 422 lmh. The work herein lays the foundation for a promising technology that, if further developed, could be applied to remediate azo dyes and COCs in textile industry effluents and groundwater sites respectively. / Thesis / Master of Applied Science (MASc)

Os azo corantes representam o maior grupo de corantes utilizados na indústria, principalmente no ramo têxtil. Sabe-se que grande parte desses produtos resiste aos sistemas de tratamento de efluente e assim, cerca de 10-15% dos corantes perdidos durante o processo de tingimento são lançados no efluente e atingem o meio ambiente. Alguns corantes desse grupo têm mostrado ser cancerígenos e mutagênicos para animais e humanos. Essa toxicidade se deve, em parte, à clivagem da ligação azo formando aminas aromáticas potencialmente cancerígenas. Ainda, a ação de sistema de metabolização nos grupamentos substituintes pode alterar a toxicidade destes compostos. Neste trabalho foram testados os azo corantes Disperse Orange 1 (4-(4--nitrofenilazo)difenilamina); pureza 96%; CAS no 2581-69-3), Disperse Red 1(N-etil-N(2-hidroxietil)-4-(4-nitrofenilazo)anilina; pureza 95%; CAS no. 2872-52-8) e Disperse Red 13 (2-[4-(2-cloro-4-nitrofenilazo)-N-etilfenilamino] etanol; pureza de 95%; CAS no 3180-81-2) usando o ensaio de mutagenicidade com Samonella. Foram utilizadas as linhagens tradicionais, TA98 e TA100 e suas respectivas derivadas com superprodução de nitroredutase e O-acetiltransferase, YG1041 e YG1042. Todos os corantes testados mostraram respostas mais altas com a linhagem TA98 em relação a TA100, o que sugere que esses compostos exercem seu efeito mutagênico principalmente por deslocamento do quadro de leitura do DNA. Para os três corantes, a resposta da linhagem YG1041 em relação a sua parental TA98 foi significativamente aumentada, mostrando a importância da nitroredutase e O-acetiltransferase na mutagenicidade desses corantes. Tal fato foi confirmado com as respostas da TA100 em relação a YG1042. O sistema de metabolização exógeno (S9) diminuiu a mutagenicidade de todos os corantes testados. Considerando os resultados obtidos com a linhagem YG1041, o corante Disperse Red 1 é o mais potente, seguido do Disperse Orange 1 e do Disperse Red 13. / Azo dyes constitute the largest group of colorants used in industry, mainly the textile one, and they pass through industrial wastewater treatment plants nearly unchanged due to their resistance to aerobic treatment. Therefore, it is estimated that 10-15% of the dyes are lost in the effluent during the dyeing process, reaching the environment. Some of these dyes have been shown to be carcinogenic and mutagenic to animals and humans. This toxic effect is, in part due to azo bond cleavage that forms potentially carcinogenic aromatic amines. The toxicity of the dyes can also be altered by the biotransformation of the substitutens. We tested the azo dyes Disperse Orange 1 (4-(4-Nitrophenylazo)diphenylamine); 96% purity; CAS number 2581-69-3), Disperse Red 1(N-Ethyl-N-(2-hydroxyethyl)-4-(4-nitrophenylazo)aniline; 95% purity; CAS number 2872-52-8) and Disperse Red 13 (2-[4-(2-Chloro-4-nitrophenylazo)-N-ethylphenylamino]ethanoll; 95% purity; CAS number 3180-81-2) using Salmonella/microssome mutagenicity assay. We used the traditional strains TA98 and TA100 and the strains with overproducing nitroreductase and O-acetyltransferase, YG1041 and YG1042, derivative of the TA 98 and TA100, respectively. All the dyes tested showed higher responses with the strain TA98 when compared with TA100, suggesting that these compounds induce mainly frameshift mutations. Moreover, we observed an increase in the mutagenicity with the overproducing nitroreductase and O-acetyltransferase strains, showing the importance of these enzymes in the mutagenicity of these dyes. In addition, for all the dyes the mutagenicity decreased after the S9 addition. According to mutagenic response with YG1041, Disperse Red 1 was the most potent, followed by Disperse Orange 1 and Disperse Red 13.