Lifetime and regeneration of immobilized titania for photocatalytic removal of aqueous hexavalent chromium [An article from: Journal of Hazardous Materials]

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Description:
Immobilized titania (TiO"2) batch reactors reduced hexavalent chromium (Cr(VI)) in the form of potassium dichromate (K"2Cr"2O"7) to trivalent chromium (Cr(III)) in aqueous solution at pH 3 under 171W/m^2 light intensity. The light source was a 125-W ultraviolet (UV) lamp. The Cr(VI) reduction showed zero-order kinetics (k"0), while the Cr(VI) adsorption fitted with first-order kinetics (k"1"s"t). Adsorption capacity increased with increasing initial Cr(VI) concentration, and the area of immobilized TiO"2 limited the reduction efficiency. The lifetime of fresh immobilized TiO"2 was approximately 14h. In addition, the regeneration of TiO"2 with 3M sodium hydroxide (NaOH) was necessary to improve adsorption reaction.