Palygorskite and SnO2-TiO2 for the photodegradation of phenol

The photocatalytic removal of phenol was studied using palygorskite-SnO2-TiO2 composites (abbreviated as Paly-SnO2-TiO2) under ultraviolet radiation. The photocatalysts were prepared by attachment of SnO2-TiO2 oxides onto the surface of the palygorskite by in situ sol-gel technique. The products were characterized by XRD. TEM and BET measurements. SnO2-TiO2 nanoparticles, with an average diameter of about 10 nm, covered the surface of the palygorskite fibers without obvious aggregation. Compared with palygorskite-titania (Paly-TiO2), palygorskite-tin dioxide (Paly-SnO2), and Degussa P25, Paly-SnO2-TiO2 and SnO2-TiO2 exhibited much higher photocatalytic activity. The photodecomposition of phenol was as high as 99.8% within 1.5 h. The apparent rate constants (k(app)) for Paly-SnO2-TiO2. TiO2, and P25 were measured. Paly-SnO2-TiO2 showed the highest rate constant (0.03435 min(-1)). The chemical oxygen demand (COD) of the phenol solution was reduced from 220.2 mg/L to 0.21 mg/L, indicating the almost complete decomposition of phenol. Reusability of the photocatalyst was proved. (C) 2010 Elsevier B.V. All rights reserved.