Photoinduced hydrophilicity and photocatalytic decomposition of endocrine-disrupting chemical pentachlorophenol on hollandite

Abstract

Surface properties and photocatalytic oxidation reactions on the hollandite-type compound K2Ga2Sn6O16 (KGSO) were examined for photoinduced hydrophilicity and oxidative decomposition of an endocrine-disrupting chemical, pentachlorophenol (C6Cl5OH, PCP), under ultraviolet (UV) illumination. The thin films and mesoporous powders of hollandite were used for examination of surface properties and photocatalysis, respectively. The photoinduced surface property was examined by measurement of the contact angle of water, ortho-chlorophenol (o-C6H4ClOH), and toluene on the surface of KGSO. The contact angle of H2O and o-C6H4ClOH decreased to 0° under UV illumination. The toluene showed little change in contact angle under UV irradiation. It is concluded that the surface of KGSO shows photoinduced hydrophilicity for H2O and aromatic compounds with hydroxyl groups (−OH). In addition, KGSO clearly showed a photo-oxidative decomposition of PCP under weak UV illumination at room temperature. The decomposition speed of C6Cl5OH on KGSO was much faster than that on previous reported nano-sized SnO2 photocatalysts. It is expected that photo-oxidative decomposition of aromatic compound will be controlled by a combination of optimum composition of the hollandite phase and control of the morphology of the hollandite particles. This suggests that hollandite would be a promising photocatalyst for decomposition of aromatic compounds in endocrine-disrupting chemicals.