Articles written in Journal of Chemical Sciences

    • Manganese zinc ferrite nanoparticles as efficient catalysts for wet peroxide oxidation of organic aqueous wastes

      Manju Kurian Divya S Nair

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      Manganese substituted zinc nanoparticles, MnxZn1−xFe2O4 (x = 0.0, 0.25, 0.5, 0.75, 1.0) prepared by sol gel method were found to be efficient catalysts for wet peroxide oxidation of 4-chlorophenol. Complete degradation of the target pollutant occurred within 90 min at 70°C. Zinc substitution enhanced the catalytic efficiency and the unsubstituted ZnFe2O4 oxidized the target compound completely within 45 min. Studies on the effect of reaction variables revealed that only a small amount of the oxidant, H2O2 (3–4 mL) is required for complete degradation of 4-chlorophenol. More than 80% of 4-chlorophenol was removed at catalyst concentrations of 100 mg/L. Direct correlation between the amount of catalyst present and the extent of degradation of 4-chlorophenol was observed, ruling out hesterogeneous-homogeneous mechanism. The catalysts are reusable and complete degradation of target pollutant occurred after five successive runs. The extent of iron leaching was fairly low after five consecutive cycles indicating the mechanism to be heterogeneous.

    • Mixed cerium nanooxides as efficient and selective C-alkylation catalysts for gas phase methylation of phenol


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      Phenol methylation is an acid-base catalysed reaction that produces valuable chemicals that are used in fine chemical synthesis. Methylation of phenol was studied over iron, vanadium and zirconium doped cerium nano oxides under optimized reaction conditions such as catalyst weight 0.5 g, phenol/methanol molar ratio 1/3 and WHSV 1.4 h-1 at 300°C and 2 h. 80-90% conversion and 90% ortho selectivity are achieved with all prepared mixed oxides. o-cresol and 2,6-xylenol are the major products of the reaction. Catalytic activity depends on the number and strength of moderate and strong acidic sites on the surface which in turn depends on the nature and composition of the catalyst. Structural stability of the catalyst substantiates the heterogeneous nature of the catalyst

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