The degradation of p-chloroaniline (PCA) by persulfate (S2O82-) activated with zero-valent iron (ZVI) was investigated through batch experiments. Effects of pH, temperature, and dosages of ZVI on PCA degradation were also examined. The degradation of PCA increased with higher dosage of ZVI due to increased activation of persulfate by zero-valent iron which generates strong oxidizing species (sulfate radicals) in aqueous solution. The PCA degradation was higher under acidic conditions (pH 2.0 and 4.0) when compared to alkaline conditions. Complete degradation of PCA was obtained by ZVI-activated persulfate at pH 4.0 at 12 min. An increase in reaction temperature from 15 to 50 degrees C significantly enhanced the PCA degradation. The aniline, N-(4-chlorophenyl)-p-phenylene di-imine, 1-(4-Chlorophenyl)-3-phenylurea and 5-chloro-2-(4-chlorophenyl diazenyl) phenol were identified as the major intermediates of PCA oxidation by persulfate. (C) 2012 Elsevier B.V. All rights reserved.