Specification of the operational parameters contribution in the efficiency of TiO2-P25 nanoparticles in the photocatalytic removal of Cr(VI) by Taguchi method

Abstract

Chromium exists in environment both as trivalent [Cr(III)] and hexavalent [Cr(VI)] forms. However, hexavalent form is five hundred times more toxic than the trivalent form. Heterogeneous photocatalysis processes, using aqueous suspensions of semiconductors, have received considerable attention in the removal of toxic metals from aqueous media. In this work the nanoparticles of TiO2-P25 in the form of slurry were used for photoreduction of Cr(VI) to the less harmful Cr(III). The process has been conducted in different operational conditions such as different initial concentrations of Cr(VI), dosage of photocatalyst, irradiation times, irradiation intensities of light and pH. For the optimization of the process Taguchi experimental design was used. The results of optimization using the Taguchi method, indicated that the pH with 28%, initial concentration of Cr(VI) with 26.99% and dosage of TiO2 nanocatalyst with 20.53% have the most effects among the selected factors. The intensity of UV light irradiation has the least effect on the efficiency of the process.