Electrochemical degradation of Reactive Blue 19 in chloride medium for the treatment of textile dyeing wastewater with identification of intermediate compounds

In the present study, electrochemical degradation experiments were conducted to degrade a textile dye namely Reactive Blue 19 (RB-19). A laboratory scale bench-top reactor was used to investigate the effect of various operating parameters using titanium based dimensionally stable anode (DSA). The oxidation of RB-19 takes place in the bulk solution with electrolytically generated chlorine/hypochlorite. Increasing the initial pH and increasing the reaction temperature decreases the de-colorization efficiency. At the same time, increasing the chloride concentration and increasing the current density showed an increase in the color removal. The complete removal of color was achieved within a short period of electrolysis for different concentrations of RB-19. However, the removal of chemical oxygen demand (COD) and total organic carbon (TOC) was 55.8% and 15.6%, respectively, for 400 mg/L RB-19 with 1.5 g/L sodium chloride concentration. The intermediate compounds formed during the degradation were identified using a gas chromatography coupled with mass spectrometry (GC/MS). In the present study, no chlorinated organic compounds were detected during the course of electrolysis. The major compounds identified were benzene, 2-hydroxy, 4,4-napthaquinoine (C.I. Natural orange 6), 1-aminoanthraquinone (C.I. Diazo fast red AL), benzyl alcohol, benzaldehyde, benzoic acid, phthalic anhydride, phthalide, phthaldehyde and 1,3-indanone.