Semiconductor-photocatalyzed degradation of carboxylic acids: Enhancement by particulate semiconductor mixture.

Degradation of oxalic acid on particulate TiO₂, ZnO, CuO, Bi₂O₃, In₂O₃, and Nb₂O₅ under UV-A light exhibits first-order kinetics, and the degradation rates increase linearly with the photon flux. All the oxides show sustainable photocatalytic activity, and the photonic efficiencies of degradation of oxalate are very much lower than those of the acid. The ease of degradation of carboxylic acids is the following: formic > oxalic > acetic > citric. Intimate mixtures of two different particulate semiconductors kept under suspension and at continuous motion exhibit higher photocatalytic activity, revealing interparticle charge transfer. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 716–726, 2009 [ABSTRACT FROM AUTHOR]