Toxicity Screening after Electrochemical Degradation of Reactive Textile Dyes

Abstract

The application of various electrodes for in situ degradation of Reactive Yellow 125 (RY125) and Reactive Green 15 (RG15) dyes, as well as ecotoxicity screening test of their degradation products were studied in this paper. The degradation process was performed in a two-electrode cylindrical cell, with Fisher platinum electrode as anode and Pd, Zr, or C electrodes as cathode; in 0.1 M Na2SO4 as supporting electrolyte. The optimal conditions (voltage and pH value) for degradation were determined in a platinum-palladium (Pt-Pd) model system for 200 mg/L of both reactive dyes. Then the electrolysis with other electrodes was conducted under the same conditions. Decolorization was monitored spectrofotometrically (UV-Vis) and the degradation efficiency was confirmed by HPLC technique with a DAD detector. Differences in degradation efficiency were observed between these three electrochemical systems (Pt-Pd, Pt-Zr, and Pt-C). The Pt-Pd system was the most efficient for the degradation of both reactive dyes. Achieved decolorization percentage for RG15 and RY125 were 98% and 97%, respectively. The ecotoxicity assessment of degradation products was performed using Anemia sauna. Toxicity data were compared by Kruskal-Wallis one-way analysis and pair-wise group comparisons with Mann-Whitney U tests. Statistically significant differences (p LT 0.05) in mortality (%) for Pt-Pd and Pt-Zr systems were determined between treated and untreated dye solutions of RG15. System Pt-C had no detectable significance in treatment of solutions of both dyes.