Ozone initiated dechlorination and degradation of trichlorophenol using Ce–Zr loaded metal oxides as catalysts

Abstract

Oxidative dechlorination and degradation of trichlorophenol (TCP) in aqueous system initiated by ozone and catalyzed by varied loadings of cerium–zirconium oxide on metal oxides supports namely; Al2O3, SiO2 and TiO2 was investigated. Catalyst materials were synthesized and characterized by using various surface characterization techniques including XRD, BET, TPD, ICP, SEM, TEM and FT-IR. XRD showed that cerium–zirconia exists as three different phases on the surface of the catalysts. SEM and SEM–EDX indicated that cerium–zirconia oxide is well dispersed on the surface of the TiO2 with compared to Al2O3 and SiO2 supports. TEM showed that particle size of Ce–Zr is in the range of 40–80nm. Catalyst testing was done as function of reaction time and pH in a semi batch reactor. The oxidation products formed in the reaction were characterized by IR, 1H NMR and LC–MS mass spectral data. Dihydroxyfumaric acid (DHFA) and oxalic acid (OA) were the main oxidation products. The product distribution was dependent on the acidic character of the catalysts. Among the catalysts tested, 2.5% Ce–Zr/SiO2 showed good activity with 100% conversion in 4h while others needed 5h.