Pentachlorophenol degradation in the heterogeneous catalytic o zonation process using Al2O3as a catalyst agent

Abstract

In this study, the catalytic ozonation of pentachlorophenol (PCP) in the presence of aluminum oxide (Al2O3) and the formation of byproducts during ozonationhas been studied. Results showed that catalytic ozonation in the presence of Al2O3 can substantially enhance PCP degradation efficiency compared with the using only ozonation process. The influences of severalenvironmental parameters including pH of the solution, initial PCP concentration, dosage of Al2O3 and dissolved ozone concentration were also investigated. The highest degradation efficiency of PCP was achieved at conditions: pH 8, 1.87 g/LAl2O3, and 0.49 g/L dissolved ozone concentration. The catalytic activity of Al2O3 was linked to highly hydroxylated surface. The surface hydroxyl groups on Al2O3 were the active places during catalytic ozonation. According to the drastic changes in the color of solution during ozonationin this study and results of some previous researches, formation of the intermediate reaction products during ozonationwas verified.Free chloride ion released, which was favored at slightly alkaline solution, was also followed in catalytic ozonation process.