The influence of solution matrix on the photocatalytic removal of color from natural waters

Abstract

Photocatalytic color removal of humic acid was studied in the presence of common inorganic anions; namely, chloride, nitrate, sulfate and phosphate ions at pH 6.8. Color removal rates were explained in terms of pseudo-first order and Langmuir-Hinshelwood kinetics. The Freundlich adsorption data were also evaluated to assess a relationship between the adsorption data and the reaction kinetics. The presence of chloride, nitrate and sulfate ions exhibited different trends when the rate is expressed as pseudo-first order reaction kinetics. In case of Langmuir-Hinshelwood kinetics, the decolorization rates were decreased in the order of the anions as, chloride, nitrate and sulfate. The presence of phosphate ions strongly inhibited the color removal rate.