The photocatalytic degradation of pentachlorophenol (PCP) using a TiO2 catalyst in a surfactant-containing system was investigated. PCP abatement by photocatalysis was significantly enhanced by the addition of cationic and nonionic surfactants, both single and mixed, at appropriate concentrations. The enhanced photodegradation can be mainly attributed to the formation of admicelles on the TiO2 surface. This phenomenon can lead to the incorporation of more PCP, thereby providing TiO2 with remarkably higher capture rates for target pollutants. Hence, PCP was rendered easily available to photo-yielded oxidative radicals on the catalyst surface. Notably, mixed cationic-nonionic surfactants yielded much higher photodegradation efficiencies than the corresponding single surfactants, indicating the existence of a synergistic effect in the complex system. The adsorption behavior of PCP on TiO2 in the surfactant solutions was investigated to elucidate this synergism. Fourier-transform infrared (FTIR) spectroscopy was adopted to gain insight into the structural changes induced by the surfactants and a better understanding of the surfactant-assisted photocatalytic degradation mechanism was obtained. (C) 2012 Elsevier B.V. All rights reserved.