The Study On The Treatment Of Pharmaceutical Intermittent Material Wastewater With High Salinity By Electrochemical Oxidation

Pharmaceutical industry discharge masses of wastewater. Pharmaceutical intermittent material wastewater contains high salinity, high chroma and high contents of organic pollutants. These organic pollutants are difficult to degrade by biology. Because of the high salinity and high COD, Electrochemical oxidation is considered. Anode materials, treatment of Pharmaceutical Intermittent Material Wastewater by Electrochemical Oxidation, produce mechanism of active chlorine, degrade mechanism of main pollutants were studied in this paper.The current efficiency has directly connections with anodic oxidation reaction of organic wastewater and selectivity of anode. The studies of the anode materials indicated, different anodes had different surface modality, different chlorine evolution over-potential, and different oxygen evolution over-potential. The performance of Ti/RuO₂ anode which adulterated TiO₂ and preparated by brush coating thermal decomposition possessed lower chlorine evolution over-potential and the lifetime of Ti/RuO₂ anode is long enough to apply for the application. Ti/ SnO₂+Sb₂O₃/β-PbO₂ anode and Ti/SnO₂ possessed higher oxygen evolution over-potential, and good catalyse capability.Compared with Ti/SnO₂+Sb₂O₃/β-PbO₂ and Ti/SnO₂ anode, using Ti/RuO₂ anode to degrade pharmaceutical intermittent material wastewater with high salinity is better. Organics, ammonia and chroma in solution were removed effectively. The removal rates of COD, ammonia and chroma are 71.3%, 96.74% and 95 % in electrochemical time of 120 min, when current density is 57.12 mA·cm^-2 and pH is 9.It had demonstrated that the addition of Cl^- in the electrolyte caused an increase in removal efficiency, and the complete degradation of pollutants could be performed due to the participation of active chlorine, which regenerated on anode surface in the electrochemical oxidation. When current density was 28.56 mA·cm^-2, NaCl concentration was 1 mol·L^-1, the concentration of active chlorine achieved 18347 mg·L^-1 after 120min. The concentration of active chlorine would be most when the NaCl concentration is 2 mol·L^-1 and the pH is 9.Through cyclic voltammetry of main pollutants in the wastewater, degrade mechanism of main pollutants are known. NH₄Cl is oxidate indirectly, when pH=13, NH₄Cl transform into NH₃·H₂O, NH₃·H₂O oxidated to N₂ directly, the other three pollutants oxidate indirectly in the surface of Ti/RuO₂ anode.