Electricalcatalytic Degradation Of Typical PPCPs By MWCNTs Electrode

PPCPs (Pharmaceutical and Personal Care Products) has been recognized as a special kind of environmental pollutants nowadays, and the conventional sewage treatment plant and water plant could not be achieved ideal removal efficiency on these pollutants. Parts of these pollutants remained in the active mud, but most of these were directly through the secondary treatment system, and then were discharged out with the effluent. So, it is necessary to look for a technology which can degrade these substances effectively.In the aquatic environment, (i.e. internal surface waters), diclofenac is a an anti-inflammatory non-steroidal drugs and hard to biodegrade, so the traditional urban sewage treatment equipment can not remove diclofenac effectually. Triclosan is a kind of bactericides that has found applications in hygiene and health. Triclosan is poorly water-soluble and it is very toxic to water living organisms since it can be photodegraded to chlorodioxins.Electrocatalytic reductive dechlorination of diclofenac in aqueous solution was studied with a multiple-walled cardon nanotubes (MWCNTs) cathode and a platinum anode. The experiments were carried out to explore the effects of initial concentration, electrolytic voltage, pH, concentration of electrolyte and electrolysis time on dechlorination. In the experiment, the results of comparison between the MWCNTs electrode and the Graphite electrode show that MWCNTs electrode was more excellent, because it has large surface area and excellent hydrogen storage capacity. The results of the Pt/MWCNTs electrode show that when the concentration of PPCPs was 50 mg·L-1, the electrolytic voltage was 30V, the pH was 11, the concentration of Na2SO4 was 1000 mg·L-1, after 8h electrocatalytic reduction, the removal rate of diclofenac reached 98%, but the removal rate of chlorine reached 80%. when the concentration of PPCPs was 1 mg·L-1, the electrolytic voltage was 30V, the pH was 7, the concentration of Na2SO4 was 1000 mg·L-1, after 8h electrocatalytic reduction, PPCPs was completely removed.SEM images show:to unpurified MWCNTs, purified MWCNTs have smaller grain diameter and more actives sites. The distribution of palladium on the electrode is discontinuous, due to the characteristic structure of MWCNTs and the mechanism of chemical deposition. MS show that hydrogen or H·is the main active substance in the degradation of pollutants on the carbon nanotubes.