Diazo dye Congo Red degradation using a Boron-doped diamond anode: An experimental study on the effect of supporting electrolytes

Diazo dye Congo Red (CR) solutions at 100 mg/L, were degraded using different supporting electrolytes in an electrochemical advanced oxidation process (EAOPs), like the anodic oxidation (AOx/BDD). All experiments were carried out in a 3 L flow reactor with a Boron-doped diamond (BDD) anode and stainless steel cathode (AISI 304), at 7.5, 15, 30 and 50 mA/cm2 current densities (j). Furthermore, each experiment was carried out under a flow rate of 7 L/min. Additionally, HClO4, NaCl, Na2SO4, and H2SO4 were tested as supporting electrolytes at a 50 mM concentration. The degradation process was at all times considerably faster in NaCl medium. Solutions containing SO42− or ClO4− ions were less prompted to degradation due to the low oxidation power of these species into the bulk. Dissolved organic carbon (DOC) analysis, was carried out to evaluate the mineralization of CR. The degradation of CR, was evaluated with the HPLC analysis of the treated solutions.