RESUMO
This study presents an attempt to solve two serious environmental problems: the generation of toxic effluents and solid waste disposal. The work proposes recycling cigarette filters with the purpose of degrading reactive dyes, which are used in the textile industry. Filters of smuggled cigarettes were recycled through Fe3+ immobilization on their surface. The material obtained was characterized through Fourier transform infrared spectroscopy (FTIR), atomic absorption spectroscopy (AAS), scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS), and ultraviolet-visible spectroscopy (UV-vis). The factorial design revealed that the most suitable conditions for the degradation of Reactive Black 5 dye were obtained by using 1 g of material at pH 3.0 in a 100 mg L-1 hydrogen peroxide solution. The material showed excellent performance in the Reactive Black 5 dye degradation process; in 60 min, 99.09 % dye was removed. At pH 7.0, the dye degradation was 72.67 %, indicating that the material prepared can be used at pH values greater than 3.0 without the occurrence of hydrated Fe3+ oxide precipitation. Furthermore, the material showed no loss of catalytic activity after three degradation studies.
Assuntos
Filtração/métodos , Naftalenossulfonatos , Poluentes Químicos da Água , Purificação da Água/métodos , Compostos Férricos/química , Resíduos Industriais , Naftalenossulfonatos/análise , Naftalenossulfonatos/química , Naftalenossulfonatos/isolamento & purificação , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificaçãoRESUMO
This research paper describes the study of a reduction-oxidation system using commercial steel wool (Fe0) and H2O2 for degradation of the dye Reactive Black 5 and aromatic compounds in water. The reductive process alone allowed the almost complete removal of color (97 ± 1 %) after 60 min of reaction. The decrease in spectral area (λ = 599 nm) associated with the chromophore group indicates breakage of the azo bonds. Moreover, the significant change in UV spectra can be associated with the formation of aromatic amines. Regarding the transformation products, a spectrophotometric method based on the diazotization reaction was employed to identify aromatic amines after reductive process, using sulfanilic acid as a model of aromatic amines. In addition, association with Fenton reagents improved the efficiency in the system with 93 ± 1 % degradation of intermediates formed during the reductive process. Ecotoxicological analysis revealed that the dye solution, after the reductive and oxidative processes, was not toxic to Lactuca sativa seeds. For Daphnia magna, the EC50 (%) values observed revealed that dye solution has an EC50(%) = 74.1 and after reductive process, the toxicity increased (EC50(%) = 63.5), which might be related to the formation of aromatic amines. However, after the Fenton process, the EC50 (%) was >100. These results demonstrated that the Fenton reaction using steel wool as an iron source was very efficient to decrease color, aromatic transformation products, and the ecotoxicity of Reactive Black 5 in solution.
Assuntos
Naftalenossulfonatos , Poluentes Químicos da Água , Animais , Daphnia/efeitos dos fármacos , Peróxido de Hidrogênio , Lactuca/efeitos dos fármacos , Naftalenossulfonatos/análise , Naftalenossulfonatos/química , Naftalenossulfonatos/toxicidade , Oxirredução , Sementes/efeitos dos fármacos , Aço , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química , Poluentes Químicos da Água/toxicidade , Purificação da ÁguaRESUMO
In this study, the Reactive Black 5 dye degradation and textile effluent were investigated using the photo-Fenton process employing immobilized Fe(3+) in acetate cellulose films. The films prepared were characterized through Fourier transform infrared spectroscopy, atomic absorption spectroscopy, scanning electron microscopy - energy-dispersive spectroscopy and ultraviolet visible spectroscopy. The factorial design revealed that the best conditions for the Reactive Black 5 dye degradation were obtained using the film containing 5% Fe (w/w), 100 mg L(-1) H2O2 and pH 4.0. In studies using artificial light, the dye degradation was 99.29% and the chemical oxygen demand (COD) reduction was 90% after 45 min of treatment. In the process assisted by sunlight, the degradation was 86% and the COD reduction was 70% considering the same time of treatment. At pH 6.0 and artificial light, the dye degradation was 98.90% and the COD reduction was 78%, indicating that the material prepared can be used at pH values greater than 3 without the occurrence of hydrated ferric oxides precipitation. It was also observed that the material can be reused seven consecutive times without substantial loss of efficacy in dye degradation. Furthermore, the proposed material reduces the COD of a textile effluent by 72% after 300 min of treatment.
Assuntos
Celulose/análogos & derivados , Naftalenossulfonatos/análise , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Poluentes Químicos da Água/análise , Análise da Demanda Biológica de Oxigênio , Celulose/química , Peróxido de Hidrogênio , Resíduos Industriais , Ferro , Naftalenossulfonatos/química , Luz Solar , Têxteis , Poluentes Químicos da Água/químicaRESUMO
Five sulfonyl aromatic alcohols, namely 4-((2-hydroxyethyl)sulfonyl)phenol, 4-((2-(2-((4-hydroxyphenyl)sulfonyl)ethoxy)vinyl)sulfonyl)phenol, 4-(ethylsulfonyl)phenol, 4-(vinylsulfonyl)phenol and 5-((4-aminophenyl)sulfonyl)-2-penten-1-ol were identified by LC-ESI-Qq-TOF-MS as products formed by electrolysis of the bisazo reactive dye Reactive Black 5 (RB5). Since electrolyses were performed in an undivided cell equipped with Ni electrodes in alkaline medium, amines like 4-(2-methoxyethylsulfonyl)benzene-amine (MEBA) with m/z 216 were also suspected to be formed due to the plausible chemical reaction in the bulk or the cathodic reduction of RB5 and its oxidation by-products. Aiming to check this hypothesis, a method was used for the preparation of MEBA with 98% purity, via chemical reduction also of the dye RB5. The logP of the synthesized sulfonyl aromatic compounds was calculated and their logkw values were determined chromatographically. These data were discussed in regard to the relationship between hydrophobicity/lipophilicity and toxicity.