Electrochemical mineralization of pentachlorophenol (PCP) by Ti/SnO2-Sb electrodes

Electrochemical degradation of pentachlorophenol (PCP) in aqueous solution was investigated over Ti/SnO2-Sb electrodes prepared by sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical measurements were used to characterize the physicochemical properties of the electrodes. The electrochemical degradation of PCP followed pseudo-first-order kinetics. The main influencing factors, including the types of supporting electrolyte (i.e., NaClO4, Na2SO4, Na2SO3, NaNO3, and NaNO2), initial concentrations of PCP (5-1000mgL(-1)), pH values (3.0-11.0), and current densities (5-40mAcm(-2)) were evaluated. The degradation and mineralization ratios of 100mgL(-1) of PCP achieved >99.8% and 83.0% after 30min electrolysis with a 10mmolL(-1) Na2SO4 at a current density of 10mAcm(-2), respectively. The corresponding half-life time (t1/2) was 3.94min. The degradation pathways that were involved in dechlorination, protons generation, and mineralization processes were proposed based on the determination of total organic carbon, chloride, and intermediate products (i.e., low chlorinated phenol and some organic acids). The toxicity of PCP and its intermediates could be reduced effectively by electrolysis. These results showed that electrochemical technique could achieve a significant mineralization rate in a short time (<30min), which provided an efficient way for PCP elimination from wastewater.