Photo-Electrochemical Treatment of Reactive Dyes in Wastewater and Reuse of the Effluent: Method Optimization

Abstract

In this work, the efficiency of a photo-electrochemical method to remove color in textile dyeing effluents is discussed. The decolorization of a synthetic effluent containing a bi-functional reactive dye was carried out by applying an electrochemical treatment at different intensities (2 A, 5 A and 10 A), followed by ultraviolet irradiation. The combination of both treatments was optimized. The final percentage of effluent decolorization, the reduction of halogenated organic volatile compound and the total organic carbon removal were the determinant factors in the selection of the best treatment conditions. The optimized method was applied to the treatment of nine simulated dyeing effluents prepared with different reactive dyes in order to compare the behavior of mono, bi, and tri-reactive dyes. Finally, the nine treated effluents were reused in new dyeing processes and the color differences (DECMC (2:1)) with respect to a reference were evaluated. The influence of the effluent organic matter removal on the color differences was also studied. The reuse of the treated effluents provides satisfactory dyeing results, and an important reduction in water consumption and salt discharge is achieved.

Photoassisted Electrochemical Treatment of Azo and Phtalocyanine Reactive Dyes in the Presence of Surfactants

“…According to these results, the decolorization kinetic constants are approximately halved with the photoassisted treatment, probably due to the action of UV on the oxidant species generated during the electrolysis [2]. …”

Estudo comparativo do tingimento de malha PES/CO com água tratada com resíduo de clarificação de óleo vegetal, na forma natural e calcinada

“…Na literatura encontram-se poucos estudos em que efluentes reais ou sintéticos foram tratados e reutilizados em novos tingimentos. No estudo realizado por SALA e colaboradores [27] ao reutilizarem efluente tratado com combinação entre tratamento eletroquímico e radiação UV, em novos tingimentos de algodão com corantes reativos, obtiveram DE entre 0,05 a 0,56, segundo autores é possível uma economia de água em até 70 %. BUSCIO e colaboradores [28] utilizaram tratamento combinado de homogeneização-decantação com ultrafiltração no tratamento de efluente, coletado em uma empresa na Espanha.…”

In situ Decolorization Monitoring of Textile Dyes for an Optimized UV-LED/TiO2 Reactor

“…Monitoring of the degree of oxidation achieved in AOPs is a crucial parameter to determine when the process is completed (i.e., measurement Chemical Oxygen Demand (COD), Total Organic Carbon (TOC), Biochemical Oxygen Demand (BOD)) [24,25,39,41]. In particular, for dyed solutions, the principal measurement of the degree of decolorization is used [49][50][51][52][53]. This analysis frequently involves a measurement of the absorbance at different times, obtained by extracting samples periodically, generating a decrease in the water volume (non-negligible in such mini reactors) and altering the photocatalysts concentration [41,42].…”