Catalytic decomposition of hydrogen peroxide and 2-chlorophenol with iron oxides

The aim of this study was to examine the catalyzed decomposition of hydroge n peroxide and 2-chlorophenol (2-CP) in the presence of iron oxides. C;ranu lar ferrihydrite, goethite, and hematite were selected as catalysts in this study. 2-CP was used as the model compound because it is a typical toxic c ompound and has not been investigated in the catalytic decomposition by iro n oxides. The catalytic activity for hydrogen peroxide decomposition follow ed the sequence: granular ferrihydrite > goethite > hematite. However, hema tite exhibited the highest activity in catalyzing 2-CP oxidation. The oxida tion efficiency of 2-CP corresponded with the inverse sequence of specific area and pH,,, of the iron oxides. The catalytic activity of granular ferri hydrite was affected significantly by the mixing speed and particle size fo r its large value of Thiele modulus (phi) and Damkohler number (Da). The st rong diffusion resistance for granular ferrihydrite was attributed either t o its microporous structure or to the formation of oxygen in the pores of t he iron oxide leading to the unexpected catalytic activity of granular ferr ihydrite to hydrogen peroxide and 2-CP. (C) 2001 Elsevier Science Ltd. All rights reserved.