Photo-Assisted Degradation, Toxicological Assessment, and Modeling Using Artificial Neural Networks of Reactive Gray BF-2R Dye
2018
do Nascimento, Graziele Elisandra | Napoleão, Daniella Carla | de Aguiar Silva, Polyana Karynne | da Rocha Santana, Rayany Magali | Bastos, Ana Maria Ribeiro | Zaidan, Léa Elias Mendes Carneiro | de Moura, Maiara Celine | Coelho, Luana Cassandra Breitenbach Barroso | Duarte, Marta Maria Menezes Bezerra
This work investigates the degradation of Reactive Gray BF-2R dye (a blend of reactive yellow 145, reactive orange 122 and reactive black 5 dyes) using UV/H₂O₂, Fenton, and photo-Fenton-advanced oxidative processes, with artificial sunlight and UV-C radiations. The photo-Fenton process employing UV-C radiation was the most efficient under the conditions studied. The ideal conditions for the degradation of the dye, determined using a factorial design 2³ and a study of the concentration of hydrogen peroxide ([H₂O₂]), were [H₂O₂] equal to 40 mg L⁻¹, iron concentration [Fe] of 1 mg L⁻¹, and pH between 3 and 4. The Chan and Chu non-linear kinetic model predicted the kinetic data with a degradation of over 98% for color and 68% for aromatics after 60 min. The behavior of the chemical oxygen demand fitted the first-order kinetic model well, with a degradation of 64% after 60 min. The Multilayer Perceptron 7-11-2 artificial neural network model enabled to model the degradation process of the aromatics and accurately predict the experimental data. Toxicity tests indicated that the post-treatment samples were non-toxic for Escherichia coli bacteria, and Portulaca grandiflora and Basil sabory seeds. However, they inhibited the growth of Lactuca sativa seeds and Salmonella enteritidis bacteria. The photo-Fenton process with UV-C radiation degraded the dye studied efficiently and the degradation percentages were, on average, 7% and 5% higher for color than those observed when employing the Fenton and UV/H₂O₂ processes, respectively. With the aromatic, however, they were 84% and 62% higher, thus justifying the use of this process.
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