Electrochemical pretreatment of coking wastewater by Ti/BTN/RuO2-IrO2-TiO2: Selectivity of chloridion oxidation and multi-response optimization

Electrooxidation pretreatment of coking wastewater with chloride-evolution electrode could remove the corrosive Cl-. However, during coking wastewater treatment, the coexisting ions and process parameters optimization, which were closely related to the removal efficiency and energy consumption, have never been investigated systematically. Herein, we firstly investigated the influences of some typical ions in coking wastewater on Clremoval. Then we employed response surface methodology to establish mathematical expressions between process parameters and response values (removal efficiency, current efficiency, and energy consumption) and implemented multi-response optimization based on desirability function. Results indicated that all the ions investigated, significantly OH-, SCN-, SO42- and NH4+, could inhibit Cl- removal by thermodynamic inhibition, competing for adsorption sites, or generating Cl- via some reactions. Moreover, the calculated optimal process parameters, which could meet maximum removal efficiency and minimum energy consumption for Cl- removal, were current density of 33.43 mA cm-2, plate distance of 10.17 cm, and initial pH of 7.32. This study systematically analyzed the factors affecting the Cl- removal and further provided ideas for optimizing pollutant removal in electrochemical pretreatment of wastewater.