Electrochemical treatment of real textile wastewater: Trichromy Procion HEXL

Abstract

[EN] The electrochemical treatment of wastewaters from the textile industry is a promising technique for not easily biodegradable compounds. This work is aimed at studying the electrochemical degradation of bifunctional reactive dyes after a real dyeing process. These are: Procion Yellow HELX®, Procion Crimson HELX® and Procion Navy HELX®, which are widely used in dyeing processes of cellulose fibers. Their structure is mainly characterized by the presence of two azo groups as chromophore group and two monochlorotriazinic groups as reactive groups. Electrolyses were carried out under galvanostatic conditions in an undivided electrolytic cell. Ti/SnO2-Sb-Pt and stainless steel electrodes were used as anode and cathode, respectively. In all cases Na2SO4 was used as electrolyte without external addition of chloride.

The degree of degradation was evaluated by means of Total Organic Carbon (TOC) and Chemical Oxygen Demand (COD) measurements.

The decolourization kinetics and the presence of the intermediates generated due to of the electrochemical treatment were studied by High Performance Liquid Chromatography (HPLC) and these studies were also carried out with UV¿Visible and Fourier Transform Infrared (FTIR) Spectroscopies.

In all cases, a decrease in TOC and COD, and a complete decolourization were obtained after the electrochemical treatment. AOS and COS data proved the presence of oxidised intermediates in solution after the electrolyses. These results suggest the possibility of reusing the treated water in several dyeing processes.