Sonocatalytic degradation of p-chlorophenol by nanoscale zero-valent copper activated persulfate under US irradiation in aqueous solutions

In this study, nanoscale zero-valent copper (nZVC) as catalyst activated persulfate (PS) was used for the degradation of p-chlorophenol (p-CP) under ultrasonic (US) irradiation in aqueous solution. The effect of different operational parameters such as solution pH (3.5-10.5), PS concentration (1-7.5 mm/L), nZVC dosage (5-35 mg/L) and initial p-CP concentration (10-100 mg/L) were evaluated at different contact time. Results indicated that US/PS/nZVC system achieve higher efficiency in p-CP degradation than US/PS, US/nZVC and PS/nZVC systems. The optimal p-CP removal efficiency (98%) was achieved within 40 min with 5 mm/L PS and 30mg/L nanocatalyst at 25 mg/L initial p-CP concentration. It was also observed that the p-CP degradation rate depends on initial p-CP concentrations. To clarity the mineralization of p-CP, TOC and COD were analyzed at optimum conditions. 61% and 75% of COD and TOC removal rate were respectively obtained from the US/PS/nZVC system within 60 min. Through the use of methanol (MA) and tert-butyl alcohol (TBA) as radical scavengers, SO_4^(°-) was identified as the main radical species that are generated during processes. The removal process of p-CP could be described by the pseudo-first-order kinetics. The apparent degradation rate constant (k) was 0.076 min-1 in US/PS/nZVC system at optimal conditions.