Study On Phenol Electrocatalytic Oxidation In Tube-in-tube Microfluidic Reactor

Phenols,produced in a variety of industries including oil refineries,pulp and paper,pharmaceuticals and coke plants,are toxic and non-biodegradable.The electrochemical catalytic oxidation processes are very promising tools for the treatment of wastewater.In this study,electrochemical oxidation of phenol was carried out in a tube-in-tube microfluidic reactor by two kinds of condition using Ti/SnO₂-Sb₂O₅ electrode.The tube-in-tube microfluidic reactor was equipped with two Ti tube electrodes of Ti/SnO₂-Sb₂O₅ and Ti tube with a micro-metric distance,used as anode and cathode,respectively.SEM and XRD were studied to characterize the phase structure and electrode surface morphology and good results were obtained.The high over oxidation potential of 2.4 V was achieved from the CV and LCV curves,which promised a high current efficiency.Electrochemical oxidation of phenol was carried out firstly in circulatory mode in the tube-in-tube microreactor.Phenol removal was higher than the degradation in parallel-plate microreactor because of the large reaction area.The kinetic analysis indicated that the first step of phenol oxidation followed pseudo-first-order reaction kinetics.Then electrochemical oxidation of phenol was operated in continuous mode.Effects of numerous operative parameters,including flow rate,current density,electrode distance,initial phenol concentration,supporting electrolyte and pH on the phenol and COD removal were systematically investigated to determine the proper operative conditions.As a result of the study,the phenol removal was decreased with the increase of flow rate,electrode distance and initial phenol concentration while increased with the increase of current density.The best supporting electrolyte concentration and pH were 0.125 mol·L-1 and 7,respectively.Complete phenol removal and COD removal of 90% were obtained for initial concentration of 60mg·L-1,flow rate of 0.8 ml·min-1 and current density of 20 mA·cm^-2.