Electrocatalytic Oxidation Of Coal Tar Processing Wastewater

Coal tar processing wastewater contains many kinds of toxic and harmful single ring,multi-ring or heterocyclic aromatic hydrocarbons,which are difficult to degrade and contain high concentration pollutants.It is difficult remove these compounds by conventional biological treatment process.Electrocatalytic oxidation technology is a novel and efficient technology in dealing with refractory substances,In this study,we have developed an electrocatalytic oxidation reactor based on the preparation of modified electrode materials to study the treatment effect of simulated tar wastewater and actual wastewater.The degradation mechanism was proposed in conjunction with electrode reaction and electrode morphology characterization.1.In this study,Ti/PbO2,Ti/MnO2/PbO2 and Ti/Sb-SnO2/PbO2 electrodes were synthesized by electrodeposition and modified from the aspects of matrix modification,adding intermediate layer and doping metal elements.The physical and chemical properties of the three electrodes were investigated by SEM,EDS,XRD,polarization scanning and accelerated life test.At last,it is concluded that Ti/Sb-SnO2/PbO2 electrode has the highest oxygen evolution potential and best catalytic activity among the three.2.The wastewater containing naphthalene and cyanide was synthesized in a simulation electrolysis experiment.The anode material,current density,electrode distance,electrolysis time,current efficiency and energy consumption are compared and analyzed.The results show that the best reaction condition when Ti/Sb-SnO2/PbO2 electrode isused as anode with the current density of 50 mA/cm 2 and the electrode distance of 0.5 cm at room temperature,under which the removal efficiency of naphthalene,COD,easy release cyanide and total cyanide is 94.4%,44.1%,55.4%and 52.4%respectively.Compared with direct current supply,Ti/Sb-SnO2/PbO2 electrode pulse power supply has the advantages of high current efficiency and low energy consumption,saving 42%.3.In a simulated experiment of wastewater with sulfur-containing cyanide,the thiocyanate radical was completely removed when the electrolysis time was 120min,under the condition that the Ti/Sb-SnO2/PbO2 electrode is used as anode with the current density of 50 mA/cm2 and the electrode distance of 0.5 cm.4.Based on the wastewater after biochemical treatment from an independent tar processing enterprise in Tangshan,electrocatalytic degradation experiment was carried out.Influence of anode type,bath voltage,electrode distance,electrolysis time and power supply was investigated.When Ti/Sb-SnO2/PbO2 electrode was applied at the operating parameters of bath voltage of 7.6 V,electrode distance of 0.5 cm,the removal rate of COD reached 81.6%and SCN-、CN-were completely oxidized and degraded after 140min reaction.