DEGRADATION AND KINETIC STUDY OF REACTIVE BLUE BF-5G AND REMAZOL RED RB 133% DYES USING FENTON AND PHOTO-FENTON PROCESS

The textile industry is responsible for the generation of highly colored effluents, which need adequate treatment. Thus, the advanced oxidative processes (AOP) have been used to degrade the dye and convert organic matter. In the present study, the degradation of the reactive blue dyes BF-5G and red remazol RB 133% were evaluated through Fenton and photo-Fenton processes (solar and sunlight). To determine the best working condition, the pH, peroxide concentration, iron concentration and time variables were evaluated by performing a kinetic study in this condition. From a preliminary study, it was verified that the Fenton and photo-Fenton processes, using different radiations, presented similar results, reaching a degradation of more than 98% for each dye. The factorial design indicated better results for a concentration of H2O2 of 10 mg · L-1, iron concentration of 5 mg · L-1 and time of 15 min, obtaining degradation above 88% for the studied dyes. A good kinetic adjustment was verified for a pseudo first order kinetic model (R2 = 0.9921 and 0.9867 for blue and red dyes, respectively). Ultimately, the study of chemical oxygen demand indicated a conversion of 75.98% for the Fenton process, 86.63% photo-Fenton solar and 87.02% photo-Fenton sunlight

Degradation of the pharmaceuticals lamivudine and zidovudine using advanced oxidation processes

The existence of pharmaceuticals in nature is a growing environmental problem, turning necessary the use of efficient treatments for the degradation of these substances, as the advanced oxidation processes (AOPs). In this work the AOPs UV/H2O2 and photo-Fenton were applied to degrade the pharmaceuticals lamivudine and zidovudine in an aqueous solution using a bench reactor, composed of three UV-C lamps. It was verified that the UV/H2O2 process presented a degradation of 97.33 ± 0.14% for lamivudine and 93.90 ± 0.33% for zidovudine, after 180 min of treatment and for an initial concentratin of each pharmaceutical of  5 mg.L-1 and [H2O2] of 600 mg.L-1.  A methodology by artificial neural networks (ANNs) was used to model the photocatalytic process, with the MLP 7-23-2 ANN representing it well, and determining the relative importance (%) of each of the input variables for the pharmaceutical’s degradation process. Kinetic studies for the pharmaceutical degradation and the conversion of organic matter showed good adjustments to the pseudo first-order models with R2 raging from 0.9705 to 0.9980. Toxicity assays for the before treatment solution indicated that the seeds Lactuca sativa and Portulaca grandiflora showed growth inhibition whereas the post-treatment solution inhibited only the growth of Lactuca sativa

Direct red 83 textile dye degradation using photoperoxidation and photo-fenton: kinetic studies, toxicity and neural networks modeling

Textile dyes have been observed in aquatic matrices that receive effluents from different textile industries. These compounds have the peculiarity of being resistant to the physical, chemical and biological treatments commonly used in wastewater treatment plants. Thus, alternative treatments such as advanced oxidative processes (AOP) have been considered in order to promote the degradation of this type of pollutant, being the photoperoxidation and photo-Fenton processes the most used. Therefore, the present work evaluated the efficiency of these AOP in the degradation of direct red 83 dye. It was found a greater efficiency of the photoperoxidation process, especially in the degradation of functional groups observed at 289 nm. This AOP presented a pseudo first order reaction kinetics, with rapid decay in the first minutes. The MLP (5-21-2) neural network model was able to satisfactorily predict the degradation of the dye under study. Finally, it was found that the proposed process showed no adverse effects when studying the toxicity in bacteria

Oxidação fotocatalítica da clozapina empregando TiO2 imobilizado em poliestireno: efeito dos parâmetros operacionais e modelagem via redes neurais

In recent years, heterogeneous photocatalysis using semiconductors has proved to be efficient for the treatment of wastewater containing organic pollutants, such as drugs. Among some photocatalysts, titanium dioxide (TiO2) has been studied and applied for this purpose. Therefore, this work investigated the photocatalytic degradation of the antipsychotic clozapine under ultraviolet irradiation, using suspended and supported TiO2 in polystyrene material. Some experimental parameters were evaluated through a factorial design 23; a higher degradation rate of the compound was verified using 0.15 g of the immobilized catalyst, [H2O2] of 340 mg L-1 and pH 9, after 6 h of treatment. It was possible to obtain degradations above 93.48% and a two-stage model was proposed to describe the reaction kinetics. An artificial neural network was used to model the photocatalytic process and to determine the importance of the operational variables. It was also established that the use of this treatment resulted in 78.30% removal of chemical oxygen demand (COD) under optimized conditions. In addition, the stability of TiO2 support after five consecutive cycles was verified from reuse tests. However, by means of toxicological tests with Escherichia coli and Salmonella enteritidis, it was observed that the products generated by the reaction were more toxic than the original compound. Nos últimos anos, a fotocatálise heterogênea através de semicondutores demonstrou ser eficiente para o tratamento de águas residuárias contendo poluentes orgânicos, como os fármacos. Dentre alguns fotocatalisadores, o dióxido de titânio (TiO2) tem sido estudado e aplicado para esta finalidade. À vista disso, neste trabalho investigou-se a degradação fotocatalítica do antipsicótico clozapina sob irradiação ultravioleta, mediante emprego de TiO2 suspenso e suportado em material de poliestireno. Alguns parâmetros experimentais foram avaliados através de um planejamento fatorial 23; verificando-se uma maior taxa de degradação do composto ao utilizar 0,15 g do catalisador imobilizado, [H2O2] de 340 mg L-1 e pH 9, após 6 h de tratamento. Para tal obteve-se degradações superiores a 93,48% e um modelo de dois estágios foi proposto para descrever a cinética reacional. Uma rede neural artificial foi utilizada para modelar o processo fotocatalítico e determinar a importância das variáveis operacionais. Também ficou estabelecido que o emprego deste tratamento resultou em 78,30% de remoção da demanda química de oxigênio (DQO) nas condições otimizadas. Além disso, a partir de testes de reutilização foi verificada a estabilidade do suporte de TiO2 após 5 ciclos consecutivos. No entanto, por meio de ensaios toxicológicos com Escherichia coli e Salmonella enteritidis observou-se que os produtos gerados através da reação geram produtos mais tóxicos que o composto original

EVALUATION OF EFFICIENCY OF ADVANCED OXIDATIVE PROCESS IN DEGRADATION OF 2-4 DICHLOROPHENOL EMPLOYING UV-C RADIATION REATOR

The study accomplished to analyze, identify and quantify 2,4-dichlorophenol employing high efficiency chromatography with a previously validated analytical methodology. The validation was made by using some analytical parameters: linearity, precision, accuracy, quantification limit (LOQ) and detection limit (LOD). The analytical curve was linear for the studied range of concentration (10 up to 100 mg.L-1) presenting a linear regression coefficient (R2) above 0,99. Regarding the methodology accuracy, a repeatability analysis was performed by observing a coefficient of variance (CV) below 20% for each of the concentrations used. The LOD and LOQ were adequate for the analyzed compound, showing the values of 1.42 mg.L-1 and 4.30 mg.L-1, respectively. The tests to verify the accuracy, by the recovery method provided values above 79%, thus resulting in specific, sensitive, precise, linear and accurate methodology in the studied concentration range. In the advanced oxidative process UV/H2O2, the compound was degraded to 88.04% under the following experimental conditions: [H2O2] = 1016.0 mg∙L-1 in 120 minutes. Therefore, it can be affirmed that the treatment employed can be used as an alternative for industrial effluent treatment with phenolic compounds.

Emprego de processos oxidativos avançados na degradação de uma mistura de corantes têxteis: avaliação de parâmetros de reação, estudo cinético, toxicidade e modelagem por redes neurais artificiais

Organic contaminants in industrial effluents threaten the quality of water resources, especially due to their resistance to natural degradation. The textile industry gain relevance, considering that it generates large volumes. This work aimed to evaluate the efficiency of different advanced oxidation processes (AOP) for the degradation of the mixture textile dyes in solution. After optimization of the main parameters involved in the applied processes and systems, the AOP with greater efficiency in the degradation of the compounds was the photo-Fenton/UV-C (92%) after 360 min of treatment. The experimental data showed a better fit to the Chan and Chu kinetic model and trough an evaluation using artificial neural networks it was possible to predict the maximum degradation achievable by the dye mixture. The toxicity assays, using multiple species of seeds indicated a treated solution with no toxic effects and that the applied methodology can be used without affecting the water resources.Contaminantes orgânicos em efluentes industriais ameaçam a qualidade dos recursos hídricos por apresentarem resistência à degradação natural. Neste sentido, a indústria têxtil ganha relevância, pois é responsável pela geração de grandes volumes de efluentes líquidos. O presente trabalho avaliou a eficiência de diferentes processos oxidativos avançados (POA) para degradação de uma mistura de corantes têxteis em solução. Após testes de eficiência e otimização dos principais parâmetros envolvidos nos processos e sistemas aplicados, o POA que apresentou maior eficiência na degradação dos compostos foi o foto-Fenton/UV-C (92%) de degradação após 360 min. Os dados experimentais do POA foto-Fenton/UV-C apresentaram melhor ajuste ao modelo de Chan e Chu e através da avaliação matemática usando rede neural artificial foi possível prever a degradação máxima da mistura de corantes. O estudo de toxicidade com sementes indicou que a solução tratada não possui efeitos tóxicos, podendo o tratamento proposto ser utilizado sem afetar recursos hídricos

Degradação dos fármacos nimesulida e ibuprofeno empregando processo foto-Fenton: estudos da toxicidade, modelagem cinética e emprego de redes neurais artificiais

The growth of pollution in aquatic environments increases every day, causing compounds like pharmaceuticas to be detected in surface waters. Thus, tecniques such as advanced oxidation processes (AOP) have been used to degrade this compounds. In this work, the efficiency of AOP in the degradation of nimesulide and ibuprofen pharmaceuticals was evaluated through chromatographic analysis as well as organic matter through the levels of chemical oxygen demand (COD) and total organic carbon (TOC). It was verified that the photo-Fenton process presented the bests results, degrading 89.70% of nimesulide and 93.35% of ibuprofen. This same process managed to reduce COD by 91.60% and mineralize 90.04% of the TOC. The kinetic study showed a good linear fit (R2=0.993) for the clustered kinetic model, as well as a good fit to the mathematical model of artificial neural networks (ANNs), with a value of R2=1.000 for the MLP4-4-1 BFGS 4567 model. Finally, the toxicity of the solution after treatment was verified against the seeds of Lactuta sativa, Cichorium endívia, Ocimum basilicum and American Hard grain. It was found that the seeds that received the solution before treatment had a lower germination amount than the ones where the post AOP treatment solution was added. Then, the root growth was evaluated, in which a relative toxic effect was observed.O crescimento da poluição de ambientes aquáticos tem aumentado todos os dias, fazendo com que compostos como os fármacos sejam verificados em águas superficiais. Desse modo, técnicas como processos oxidativos avançados (POA) tem sido utilizadas. Neste trabalho a eficiência dos POA na degradação dos fármacos nimesulida e ibuprofeno foi avaliada, através de análises cromatográficas, bem como de matéria orgânica através dos níveis de demanda química de oxigênio (DQO) e carbono orgânico total (COT). Verificou-se que o processo foto-Fenton apresentou os melhores resultados degradando 89,70% do nimesulida e 93,35% do ibuprofeno. Esse mesmo processo conseguiu reduzir em 91,60% a DQO e mineralizar 90,04% do COT. O estudo cinético mostrou bom ajuste linear (R2=0,993) para o modelo cinético agrupado, além de uma boa adequação ao modelo matemático de redes neurais artificiais (RNA), com um valor de R2=1,000 para o modelo MLP4-4-1 BFGS4567. Por fim, verificou-se a toxicidade da solução após tratamento, frente às sementes de Lactuta Sativa, Cichorium endívia, Ocimum basilicum e do grão Americano Hard. Verificou-se que as sementes que receberam a solução antes do tratamento apresentaram uma quantidade menor germinação, do que quando foi adicionada a solução pós-tratamento via POA. Em seguida, avaliou-se o crescimento radicular, no qual foi percebido relativo efeito tóxico

Evaluation of the degradation potential of different advanced oxidation processes for a textile dye mixture: a kinetic study with mathematical modeling and toxicological tests

Studies and research have been developed around the world on environmental pollution. Among the most diverse types of pollutants, textile dyes have attracted attention in the Brazilian Northeast. These compounds, besides being persistent, resist to the conventional treatments applied in the wastewater treatment plants. Thus, the present study evaluated the degradation of the mixture of direct red 23, direct red 227 and direct orange 26 dyes by advanced oxidation processes (AOPs). It was observed that the homogeneous AOPs were more efficient, being able to degrade 100% of the chromophoric groups after the optimization of the variables [H2O2], [Fe] and pH. The reaction kinetics for the photo-Fenton process followed a pseudo-first order non-linear model, with rapid decay of the concentrations in the first 60 min. Aiming to have a methodology capable of predicting the degradation efficiency for the studied processes, it was verified that the artificial neural networks MLP 4-9-3 and MLP 5-6-3 well represent the data from the homogeneous and heterogeneous processes, respectively. A toxicity study was carried out using seeds, bacteria and microcrustaceans and it was found that the intermediate compounds formed during the treatment process act differently for each of them

Avaliação cinética e ecotoxicológica da degradação do corante têxtil direct orange 26 por processos Fenton e foto-Fenton/solar

The presence of color in textile effluents has been studied because of the need for more effective treatments. Therefore, advanced oxidative processes (AOP) have been used in the degradation of dyes, as well as in the conversion of organic matter. This study evaluated the degradation of the direct orange 26 textile dye by Fenton and photo-Fenton processes (with natural solar radiation). A statistical analysis, based on factorial 23 indicated the best working conditions, being: [H2O2] = 100 mg·L-1 and pH 3-4, for both AOP in that the [Fe] =  1 e 5 mg·L-1, for photo-Fenton and Fenton, respectively. The results of the kinetic studies demonstrated a good fit to the nonlinear kinetic model proposed by Chan and Chu, with values of R2 > 0,996 (photo-fenton) and R2 > 0,939 (Fenton). The tests performed to evaluate the chemical oxygen demand indicated conversions of 62.05% (Fenton) and 66.41% (photo-Fenton). Finally, the ecotoxicity study indicated that the post-treatment samples were non-toxic to the bacteria Escherichia coli and Proteus mirabilis but showed growth inhibition for Lactuca sativa (Fenton and photo-Fenton) seeds and for Brassica juncea and Portulaca grandiflora (Fenton).A presença de cor em efluentes têxteis tem sido alvo de estudo, devido a necessidade de tratamentos mais eficazes. Diante disso, processos oxidativos avançados (POA) têm sido utilizados na degradação de corantes, assim como na conversão da matéria orgânica. Este estudo avaliou a degradação do corante têxtil laranja direto 26 via processos Fenton e foto-Fenton (com radiação solar natural). Uma análise estatística, baseada em planejamentos fatoriais 23 indicaram as melhores condições de trabalho, sendo elas: [H2O2] = 100 mg·L-1 e pH 3-4, para ambos os POA em quanto que a [Fe] =  1 e 5 mg·L-1, para o foto-Fenton e o Fenton, respectivamente. Os resultados dos estudos cinéticos demonstraram um bom ajuste ao modelo cinético não-linear proposto por Chan e Chu apresentando R2 > 0,996 (foto-Fenton) e R2 > 0,939 (Fenton). Os ensaios realizados para avaliação da demanda química de oxigênio indicaram conversões de 62,05% (Fenton) e 66,41% (foto-Fenton). Por fim, o estudo de ecotoxicidade indicou que as amostras pós-tratamento não são tóxicas para as bactérias Escherichia coli e Proteus mirabilis, mas apresentou inibição do crescimento para sementes de Lactuca sativa (Fenton e foto-Fenton) e para Brassica juncea e Portulaca grandiflora (Fenton)

Degradation of the pharmaceuticals lamivudine and zidovudine using advanced oxidation processes

The existence of pharmaceuticals in nature is a growing environmental problem, turning necessary the use of efficient treatments for the degradation of these substances, as the advanced oxidation processes (AOPs). In this work the AOPs UV/H2O2 and photo-Fenton were applied to degrade the pharmaceuticals lamivudine and zidovudine in an aqueous solution using a bench reactor, composed of three UV-C lamps. It was verified that the UV/H2O2 process presented a degradation of 97.33 ± 0.14% for lamivudine and 93.90 ± 0.33% for zidovudine, after 180 min of treatment and for an initial concentratin of each pharmaceutical of  5 mg.L-1 and [H2O2] of 600 mg.L-1.  A methodology by artificial neural networks (ANNs) was used to model the photocatalytic process, with the MLP 7-23-2 ANN representing it well, and determining the relative importance (%) of each of the input variables for the pharmaceutical’s degradation process. Kinetic studies for the pharmaceutical degradation and the conversion of organic matter showed good adjustments to the pseudo first-order models with R2 raging from 0.9705 to 0.9980. Toxicity assays for the before treatment solution indicated that the seeds Lactuca sativa and Portulaca grandiflora showed growth inhibition whereas the post-treatment solution inhibited only the growth of Lactuca sativa