Comparative study of degradation of 4-chlorophenol by ultraviolet irradiation/sodium hypochlorite and ultraviolet irradiation/ozonation

摘要

The photochemical oxidation of 4-chlorophenol solutions by ultraviolet irradiation/sodiumnhypochlorite (UV/NaClO) and ultraviolet irradiation/ozonation (UV/O3) respectively was studiednin a pilot scale photochemical reactor. The degradation efficiency of UV/NaClO was lower thannthat of UV/O3. The final UV absorption removals of the two processes were approximately 80%nand approximately 90% respectively. During the two processes, dihydroxylated chlorophenolsnwere the main intermediates. And pH values decreased with the oxidation being carried on.nHowever, the UV/NaClO process was incomplete and some adsorbable organic halogens,nsuch as ethyl 2-chloroacetate, 3,4-dichlorobut-3-en-2-one, ethyl 2,2-dichloroacetate,n2-chloro-1,1-diethoxyethane, ethyl 2,2,2-trichloroacetate and 2,4,6-trichlorophenol, still existed innthe final solution. The costs of the two processes were also estimated. On a small scale,nUV/NaClO process had significant economic advantage.