WET OXIDATIVE METHOD FOR REMOVAL OF 2-CHLOROPHENOL IN WATER USING Fe(III), Co(II), Ni(II) and Cu(II) -IMPREGNATED SiO2 CATALYSTS
The common practice of microbiological oxidation of organic pollutants in the effluents of organochemical and petroleum-based industries is not effective in mineralizing chlorinated phenols, which are persistent and toxic to organisms even at low concentrations. Effluents containing these recalcitrant organics require tertiary treatment and catalytic wet oxidation (CWO) has shown tremendous promise in this regard. The present work emphasizes on the catalytic wet oxidation of 2-chlorophenol (2-CP) with the assistance of catalysts prepared by impregnating transition metal ions [Fe(III), Co(II), Ni(II) and Cu(II)] on the surface of SiO2. The structural features of the catalyst were determined with FTIR, powder XRD and SEM. The amount of metal entering into silica matrix was estimated with atomic absorption spectrometry(AAS). The oxidation was carried out in a high-pressure stirred reactor at different process variables. The conversion achieved with Fe(III), Co(II), Ni(II) and Cu(II) impregnated SiO2 in 6 h is respectively 61.7, 78.3, 59.2 and 73.5% with 2-CP:H2O2 molar ratio of 1:1. It was observed that with increasing temperature, catalyst load and mole ratio of H2O2 in the feed, the oxidative conversion could be further improved both in presence of the chemical oxidant and without it. Effects of various reaction conditions, kinetics of the catalytic process and the probable mechanism of oxidation have been discussed.