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Brenda Roberta Silveira De ,araújo - One of the best experts on this subject based on the ideXlab platform.
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Degradação eletroquímica de cloreto de cetrimônio com diamante dopado com boro
2015Co-Authors: Brenda Roberta Silveira De ,araújoAbstract:A poluição do meio ambiente é um dos maiores problemas mundiais, resultando em alterações que ameaçam à qualidade dos solos, da atmosfera e da água. O crescimento populacional, o aumento das atividades industriais, a falta de conscientização ambiental e de informação sobre uso de substâncias poluentes são fatores que agravam essa problemática. Diante da necessidade de minimizar impactos causados por diversos poluentes descartados em ambientes aquáticos se tem normalmente o tratamento destes efluentes por meio de processos biológicos, que apesar do baixo custo e muitas vezes eficientes, não se mostram efetivos com alguns compostos orgânicos que não são biodegradáveis e requerem a utilização de tecnologias de oxidação mais avançadas, como por exemplo, os processos eletroquímicos baseados na geração de radicais oxidantes. Este método vem demonstrando ser eficiente para a degradação de uma ampla gama de compostos orgânicos, com o intuito final de reduzir ao máximo a complexidade das moléculas e resíduos gerados no processo. A grande vantagem dos métodos eletroquímicos para o tratamento de poluentes orgânicos reside na não necessidade de uso de reagentes oxidantes perigosos, sendo utilizado no seu lugar um reagente intrinsecamente “limpo”, o elétron. Além disto, os processos de oxidação eletroquímica passam por ser facilmente monitoráveis, controláveis e automatizáveis. Dentro dos diferentes tipos de materiais eletródicos existentes no mercado, destaca-se o diamante dopado com boro, especialmente eficiente por possuir uma ampla janela eletroquímica, alta estabilidade química e mecânica e uma boa eficiência para remoção de efluentes orgânicos através da oxidação por meio da ação do radical hidroxila, que bem direta ou indiretamente, mediante a geração de outras espécies intermediárias fortemente oxidantes. Neste contexto, o diamante dopado com boro pode ser uma boa alternativa para o tratamento de efluentes de indústrias cosméticas, as quais podem conter o cloreto de cetrimônio (hexadeciltrimetilamônio) utilizado como emulsificante. O principal problema deste composto é a limitada biodegradabilidade que apresenta tal como relatado pela Agência de Proteção Meio Ambiental Estadunidense. Com estas premissas, este trabalho de conclusão de curso se apresenta como o primeiro trabalho do Laboratório de Desenvolvimento de Processos Químicos do Instituto de Química da Universidade de Brasília na área de tratamento de efluentes aquosos poluídos com contaminantes orgânicos mediante tecnologia eletroquímica em Degradação eletroquímica do cloreto de cetrimônio com diamante dopado com boro um reator tipo filtro-prensa. Devido a isto, uma parte importante do trabalho foi a montagem e o start-up deste, após o qual, foi avaliada a possibilidade de tratamento de um efluente sintético contendo cloreto de cetrimônio como poluente orgânico, sendo estudado a influencia da carga elétrica fornecida ao sistema (quantidade de elétrons) e a vazão de alimentação ao reator eletroquímico. Como resultados mais relevantes, em primeiro lugar, pode ser destacada a montagem e posta em funcionamento do sistema de forma satisfatória, além da demonstração preliminar de tratamento por meio desta tecnologia de efluentes contendo cloreto de cetrimônio na sua composição. _________________________________________________________________________ ABSTRACTThe environmental polution is one of the main worldwide problems, leading to alterations that threaten the quality of the soils, atmosphere and the aquatic ecosystem. The population growth, the increase in the industrial activities, the lack of environmental awareness and information about the use of pollutant substances are factors that worsen these issues. Biological processes are normally used in order to minimize the impacts ascribed by the different pollutants released in aquatic environments. Despite the low cost and the reliability, they are not effective for not readily biodegradable compounds, demanding the use of more advanced technologies, for instance, the electrochemical processes based on the hydroxyl radical generation. This method has proven to be efficient for the degradation of a large variety of organic compounds, with the final goal of reducing as much as possible the complexity of the molecules and the residues generated in the process. The primary advantage of the electrochemical methods for the organic pollutant treatment lies in the non-requirement of hazardous oxidant, being used instead a reagent intrinsically “green”, the electron. Moreover, the electrochemical oxidation processes are easily monitored, controlled and automatized. Among the different types of commercial electrodic materials, boron doped diamond stands out, especially efficient due to the large electrochemical window, high chemical and mechanical stability e a good efficiency for the removal of organic pollutants through the action of the direct action of the hydroxyl radical or the indirect effect by means of the generation of powerful intermediate oxidants. In this context, the boron doped diamond can be a good alternative for the treatment of effluents coming from cosmetic industries, which can content Cetrimonium Chloride (hexadecyltrimethylammonium), widely used as emulsifier. The main problem of this compound is the limited biodegradability, as related by the United State Environmental Protection Agency. With these premises, this degree thesis constitutes the first work in the Laboratory of Chemical Processes Development of the Institute of Chemistry of the University of Brasília in the field of aqueous effluents polluted with organic contaminants by electrochemical technology in a filter-press reactor. Due to this, an important part of this work was the mounting and start-up of this, after which it was assessed the possibility of treating a synthetic effluent containing Cetrimonium Chloride as organic pollutant, Degradação eletroquímica do cloreto de cetrimônio com diamante dopado com boro being studied the influence of the electrical charge supplied (amount of electrons) and the feed flow rate. As the most relevant results, it can be pointed out a satisfactory mounting and start-up of the system, in addition to the preliminary demonstration of treatment, by using this technology, of Cetrimonium Chloride containing effluents
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Degradação eletroquímica de cloreto de cetrimônio com diamante dopado com boro
2014Co-Authors: Brenda Roberta Silveira De ,araújoAbstract:Monografia (graduação)—Universidade de Brasília, Instituto de Química, 2014.A poluição do meio ambiente é um dos maiores problemas mundiais, resultando em alterações que ameaçam à qualidade dos solos, da atmosfera e da água. O crescimento populacional, o aumento das atividades industriais, a falta de conscientização ambiental e de informação sobre uso de substâncias poluentes são fatores que agravam essa problemática. Diante da necessidade de minimizar impactos causados por diversos poluentes descartados em ambientes aquáticos se tem normalmente o tratamento destes efluentes por meio de processos biológicos, que apesar do baixo custo e muitas vezes eficientes, não se mostram efetivos com alguns compostos orgânicos que não são biodegradáveis e requerem a utilização de tecnologias de oxidação mais avançadas, como por exemplo, os processos eletroquímicos baseados na geração de radicais oxidantes. Este método vem demonstrando ser eficiente para a degradação de uma ampla gama de compostos orgânicos, com o intuito final de reduzir ao máximo a complexidade das moléculas e resíduos gerados no processo. A grande vantagem dos métodos eletroquímicos para o tratamento de poluentes orgânicos reside na não necessidade de uso de reagentes oxidantes perigosos, sendo utilizado no seu lugar um reagente intrinsecamente “limpo”, o elétron. Além disto, os processos de oxidação eletroquímica passam por ser facilmente monitoráveis, controláveis e automatizáveis. Dentro dos diferentes tipos de materiais eletródicos existentes no mercado, destaca-se o diamante dopado com boro, especialmente eficiente por possuir uma ampla janela eletroquímica, alta estabilidade química e mecânica e uma boa eficiência para remoção de efluentes orgânicos através da oxidação por meio da ação do radical hidroxila, que bem direta ou indiretamente, mediante a geração de outras espécies intermediárias fortemente oxidantes. Neste contexto, o diamante dopado com boro pode ser uma boa alternativa para o tratamento de efluentes de indústrias cosméticas, as quais podem conter o cloreto de cetrimônio (hexadeciltrimetilamônio) utilizado como emulsificante. O principal problema deste composto é a limitada biodegradabilidade que apresenta tal como relatado pela Agência de Proteção Meio Ambiental Estadunidense. Com estas premissas, este trabalho de conclusão de curso se apresenta como o primeiro trabalho do Laboratório de Desenvolvimento de Processos Químicos do Instituto de Química da Universidade de Brasília na área de tratamento de efluentes aquosos poluídos com contaminantes orgânicos mediante tecnologia eletroquímica em Degradação eletroquímica do cloreto de cetrimônio com diamante dopado com boro um reator tipo filtro-prensa. Devido a isto, uma parte importante do trabalho foi a montagem e o start-up deste, após o qual, foi avaliada a possibilidade de tratamento de um efluente sintético contendo cloreto de cetrimônio como poluente orgânico, sendo estudado a influencia da carga elétrica fornecida ao sistema (quantidade de elétrons) e a vazão de alimentação ao reator eletroquímico. Como resultados mais relevantes, em primeiro lugar, pode ser destacada a montagem e posta em funcionamento do sistema de forma satisfatória, além da demonstração preliminar de tratamento por meio desta tecnologia de efluentes contendo cloreto de cetrimônio na sua composição.The environmental polution is one of the main worldwide problems, leading to alterations that threaten the quality of the soils, atmosphere and the aquatic ecosystem. The population growth, the increase in the industrial activities, the lack of environmental awareness and information about the use of pollutant substances are factors that worsen these issues. Biological processes are normally used in order to minimize the impacts ascribed by the different pollutants released in aquatic environments. Despite the low cost and the reliability, they are not effective for not readily biodegradable compounds, demanding the use of more advanced technologies, for instance, the electrochemical processes based on the hydroxyl radical generation. This method has proven to be efficient for the degradation of a large variety of organic compounds, with the final goal of reducing as much as possible the complexity of the molecules and the residues generated in the process. The primary advantage of the electrochemical methods for the organic pollutant treatment lies in the non-requirement of hazardous oxidant, being used instead a reagent intrinsically “green”, the electron. Moreover, the electrochemical oxidation processes are easily monitored, controlled and automatized. Among the different types of commercial electrodic materials, boron doped diamond stands out, especially efficient due to the large electrochemical window, high chemical and mechanical stability e a good efficiency for the removal of organic pollutants through the action of the direct action of the hydroxyl radical or the indirect effect by means of the generation of powerful intermediate oxidants. In this context, the boron doped diamond can be a good alternative for the treatment of effluents coming from cosmetic industries, which can content Cetrimonium Chloride (hexadecyltrimethylammonium), widely used as emulsifier. The main problem of this compound is the limited biodegradability, as related by the United State Environmental Protection Agency. With these premises, this degree thesis constitutes the first work in the Laboratory of Chemical Processes Development of the Institute of Chemistry of the University of Brasília in the field of aqueous effluents polluted with organic contaminants by electrochemical technology in a filter-press reactor. Due to this, an important part of this work was the mounting and start-up of this, after which it was assessed the possibility of treating a synthetic effluent containing Cetrimonium Chloride as organic pollutant, Degradação eletroquímica do cloreto de cetrimônio com diamante dopado com boro being studied the influence of the electrical charge supplied (amount of electrons) and the feed flow rate. As the most relevant results, it can be pointed out a satisfactory mounting and start-up of the system, in addition to the preliminary demonstration of treatment, by using this technology, of Cetrimonium Chloride containing effluents
Rizwana Mobin - One of the best experts on this subject based on the ideXlab platform.
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Resolution of a Three-Component Mixture of Methyl Group Substituted Cationic Surfactants by Use of a Green Eluent: A Thin-Layer Chromatographic Approach
JPC – Journal of Planar Chromatography – Modern TLC, 2015Co-Authors: Ali Mohammad, Rizwana MobinAbstract:Three methyl groups containing quaternary ammonium compounds have been separated and identified by thin-layer chromatography using green solvents. Silica gel G and n -butanol-40% aq. ethylene glycol-ethyl acetate (6:4:1) have been found the most favorable for the resolution of three cationic surfactants (Cetrimonium Chloride-benzyl trimethylammonium Chloride—tetramethylammonium hydroxide). Densitographic separation pattern has been presented. The limits of detection for Cetrimonium Chloride, benzyl trimethylammonium Chloride, and tetramethylammonium hydroxide have been determined. The mobility trend of separated surfactants was also examined by replacing n -butanol with other alcohols. Chromatographic parameters like Δ R _F, separation factor ( α ), and resolution ( R _S) for the separation have been calculated. The effect of the presence of foreign substances such as metal cations, metal anions, amino acids, and vitamins as impurities on separation has been examined. The proposed method has been successfully applied for the identification of Cetrimonium Chloride in commercially available shampoo sample.
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Resolution of a three-component mixture of methyl group substituted cationic surfactants by use of a green eluent: A thin-layer chromatographic approach
Journal of Planar Chromatography – Modern TLC, 2015Co-Authors: Ali Mohammad, Rizwana MobinAbstract:Three methyl groups containing quaternary ammonium compounds have been separated and identified by thin-layer chromatography using green solvents. Silica gel G and n-butanol-40% aq. ethylene glycol-ethyl acetate (6:4:1) have been found the most favorable for the resolution of three cationic surfactants (Cetrimonium Chloride-benzyl trimethylammonium Chloride-tetramethylammonium hydroxide). Densitographic separation pattern has been presented. The limits of detection for Cetrimonium Chloride, benzyl trimethylammonium Chloride, and tetramethylammonium hydroxide have been determined. The mobility trend of separated surfactants was also examined by replacing n-butanol with other alcohols. Chromatographic parameters like ΔRF, separation factor (α), and resolution (RS) for the separation have been calculated. The effect of the presence of foreign substances such as metal cations, metal anions, amino acids, and vitamins as impurities on separation has been examined. The proposed method has been successfully appli...
Ali Mohammad - One of the best experts on this subject based on the ideXlab platform.
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Resolution of a Three-Component Mixture of Methyl Group Substituted Cationic Surfactants by Use of a Green Eluent: A Thin-Layer Chromatographic Approach
JPC – Journal of Planar Chromatography – Modern TLC, 2015Co-Authors: Ali Mohammad, Rizwana MobinAbstract:Three methyl groups containing quaternary ammonium compounds have been separated and identified by thin-layer chromatography using green solvents. Silica gel G and n -butanol-40% aq. ethylene glycol-ethyl acetate (6:4:1) have been found the most favorable for the resolution of three cationic surfactants (Cetrimonium Chloride-benzyl trimethylammonium Chloride—tetramethylammonium hydroxide). Densitographic separation pattern has been presented. The limits of detection for Cetrimonium Chloride, benzyl trimethylammonium Chloride, and tetramethylammonium hydroxide have been determined. The mobility trend of separated surfactants was also examined by replacing n -butanol with other alcohols. Chromatographic parameters like Δ R _F, separation factor ( α ), and resolution ( R _S) for the separation have been calculated. The effect of the presence of foreign substances such as metal cations, metal anions, amino acids, and vitamins as impurities on separation has been examined. The proposed method has been successfully applied for the identification of Cetrimonium Chloride in commercially available shampoo sample.
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Resolution of a three-component mixture of methyl group substituted cationic surfactants by use of a green eluent: A thin-layer chromatographic approach
Journal of Planar Chromatography – Modern TLC, 2015Co-Authors: Ali Mohammad, Rizwana MobinAbstract:Three methyl groups containing quaternary ammonium compounds have been separated and identified by thin-layer chromatography using green solvents. Silica gel G and n-butanol-40% aq. ethylene glycol-ethyl acetate (6:4:1) have been found the most favorable for the resolution of three cationic surfactants (Cetrimonium Chloride-benzyl trimethylammonium Chloride-tetramethylammonium hydroxide). Densitographic separation pattern has been presented. The limits of detection for Cetrimonium Chloride, benzyl trimethylammonium Chloride, and tetramethylammonium hydroxide have been determined. The mobility trend of separated surfactants was also examined by replacing n-butanol with other alcohols. Chromatographic parameters like ΔRF, separation factor (α), and resolution (RS) for the separation have been calculated. The effect of the presence of foreign substances such as metal cations, metal anions, amino acids, and vitamins as impurities on separation has been examined. The proposed method has been successfully appli...
Günter K. Krieglstein - One of the best experts on this subject based on the ideXlab platform.
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The effect of preservatives and antiglaucomatous medication on the histopathology of the conjunctiva
Graefe's Archive for Clinical and Experimental Ophthalmology, 1994Co-Authors: Holger Mietz, Ulrike Niesen, Günter K. KrieglsteinAbstract:• Background: Topical medication applied chronically for the treatment of glaucoma changes the cellular profile of the conjunctiva. We wanted to determine the role of preservatives, which are usually combined with the drugs, on this effect • Methods: We applied metipranolol 0.3 % and pilocarpine 2 % with and without benzalkonium Chloride 0.01 % and Cetrimonium Chloride 0.004 %, respectively. Twenty-four rabbits, divided into four groups, were treated for 3 months. The complete globes and the adherent bulbar conjunctiva were examined histopathologically and immunohistochemically • Results: With special stains for collagen, a slight increase of the thickness of subepithelial collagen of the conjunctiva was present in both groups treated with medication and preservative compared with eyes treated with medication alone. This effect was also true for special antibodies for collagen type IV and α -smooth muscle actin in the eyes treated with pilocarpine, but not in the eyes treated with metipranolol • Conclusion: The results suggest that preservatives may have an additional adverse effect on the conjunctiva in addition to the effects of the medications alone.
M.a. Deyab - One of the best experts on this subject based on the ideXlab platform.
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Effect of some organic surfactants on the electrochemical behaviour of carbon steel in formation water
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2005Co-Authors: S.t. Keera, M.a. DeyabAbstract:The effect of adding some organic surfactants, cocamide diethanol amine as a nonionic surfactant (NS), Cetrimonium Chloride as a cationic surfactant (CS), and cocamidopropyl betaine as an amphoteric surfactant (AmS), on the electrochemical behaviour of carbon steel in formation water was investigated by using a potentiodynamic and impedance techniques. Results reported in this study show that the addition of these surfactants inhibits the corrosion of carbon steel and the extent of inhibition depends upon the type and concentration of the surfactant. The inhibition efficiency for three organic surfactants increase with the increase in the surfactants concentration but decrease with increasing temperature. The inhibition efficiency of each of AmS, NS, and CS reaches a maximum value around their critical micelle concentrations. The percentage of corrosion inhibition of these surfactants decreases in the order AmS > NS > CS. The inhibition occurs through adsorption of the organic surfactants on the metal surface without modifying the mechanism of corrosion process. The experimental data fit both of Flory-Huggins and kinetic-thermodynamic isotherm.