Lifetime and regeneration of immobilized titania for photocatalytic removal of aqueous hexavalent chromium

• Published in: Journal of hazardous materials 2005-09, Vol.124 (1), p.53-58
• Main Authors: Tuprakay, Seree, Liengcharernsit, Winai
• Format: Article
• Language: English
• Subjects: Adsorption; Applied sciences; Catalysis; Catalytic reactions; Chemical engineering; Chemistry; Chromium - isolation & purification; Cr(VI); Exact sciences and technology; General and physical chemistry; Immobilized titania; Lifetime; Osmolar Concentration; Oxidation-Reduction; Photocatalytic; Photochemistry - methods; Pollution; Reactors; Regeneration; Solutions - chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Titanium - chemistry; Water - chemistry; Water Pollutants, Chemical - isolation & purification
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2005.03.027

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 171 W/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 1st). 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 14 h. In addition, the regeneration of TiO 2 with 3 M sodium hydroxide (NaOH) was necessary to improve adsorption reaction.