Decontamination of real textile industrial effluent by strong oxidant species electrogenerated on diamond electrode: Viability and disadvantages of this electrochemical technology

In a previous work [1], the treatment of dye solutions containing Remazol Red BR (RRB) and Novacron Blue C-D (NB) by anodic oxidation using boron doped diamond anode (BDD) demonstrated that the electrochemical treatment is an efficient alternative for removing color and chemical oxygen demand (COD) and this technology can be used for depuration of real effluents. More recently, these assumptions have been confirmed by oxidizing electrochemically a real textile effluent using BDD anode [2]. Then, as a further development of the research carried out in these previous studies [1] and [2], in the present work, it has been considered appropriate to extend the investigation to the anodic oxidation, using BDD anode, of a specific real effluent discharged by Brazilian textile industry, adding Na2SO4 or NaCl salts in order to verify the applicability of this treatment producing in situ strong oxidant species (peroxodisulfates or active chlorine, respectively).In this study, we also attempt to discuss critical evidence about the viability of peroxodisulfates or active chlorine. Results obtained in this research clearly demonstrated that the effect of the electrogenerated strong oxidant species, peroxodisulfates or active chlorine, depends on electrocatalytic mechanism followed on BDD surface, improving the color and COD removal. However, there is a limit of NaCl for treating real effluents avoiding the formation of organochloride compounds; and it is a subject of critical importance, from the environmental point of view, to apply this alternative treatment.

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► Electrogenerated strong oxidants on BDD surface improve the color and COD removals.
► Active chlorine species can generate organochlorinated compounds at the end of treatment.
► Chloroform is a recalcitrant and persistent by-product formed.
► Catalytic alternative processes to eliminate organic pollutants from industrial effluents.