Electrocatalytic removal of phenol from coking wastewater using coal based electrode materials

An efficient electrochemical system for phenol degradation in coking wastewater was established. Wherein the economic homemade coal electrode materials (CEMs) and titanium electrode were used as the work electrodes. The removal rate of phenol (R) was 70.18% before optimized and 99.91% after optimized by response surface method (RSM) in phenol synthetic wastewater, and the removal rate of TOC was 72.81%. The operating conditions are: current density of 10 mA/cm2, initial phenol concentration of 100 mg/L, pH of 2, processing time of 270 min and electrolyte concentration (NaCl) of 0.7 mol/L. The R was 95.23% in actual coking water experiment with this process conditions, meanwhile the average removal rate of COD and NH3-N was 93.56% and 85.0%. The free radical quenching experiments result by different dose of tert-butanol (TBA) proved the dominant active material of ·OH in oxidation process, the R was decreased from 99.91% to 73.24% (TBA: 0.7 mol/L) and 37.53% (TBA: 2.0 mol/L). The intermediates products most likely existed as hydroquinone, benzoquinone and catechol. synergistic effect on adsorption and oxidation of the electrode was certified. The whole process included three consecutive stages as adsorption, oxidation, desorption/oxidation. CEMs provided the active adsorption site and micro-electric field to improve the efficiency of oxidative degradation.