Palygorskite and SnO2–TiO2 for the photodegradation of phenol

Abstract The photocatalytic removal of phenol was studied using palygorskite-SnO 2 –TiO 2 composites (abbreviated as Paly-SnO 2 –TiO 2 ) under ultraviolet radiation. The photocatalysts were prepared by attachment of SnO 2 –TiO 2 oxides onto the surface of the palygorskite by in situ sol–gel technique. The products were characterized by XRD, TEM and BET measurements. SnO 2 –TiO 2 nanoparticles, with an average diameter of about 10 nm, covered the surface of the palygorskite fibers without obvious aggregation. Compared with palygorskite-titania (Paly-TiO 2 ), palygorskite-tin dioxide (Paly-SnO 2 ), and Degussa P25, Paly-SnO 2 –TiO 2 and SnO 2 –TiO 2 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-SnO 2 –TiO 2, TiO 2 , and P25 were measured. Paly-SnO 2 –TiO 2 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.