Enhanced photocatalytic activity of nafion-coated TiO2

Photocatalytic degradation (PCD) of aqueous paraquat was accelerated by the addition of either phosphate or sulfate salt. Attachment of these anions to the TiO(2) surface possibly results in increased adsorption of the cationic paraquat species and in turn its photocatalysis rate. The same effect was obtained more consistently using the Nafion : tan anionic polymer)-coated TiO(2). Enhanced PCD of paraquat and some amine compounds was noted, However the anionic and neutral compounds were not affected significantly. Nafion proved to be Stable against photocatalysis. It has been suggested that the degradation rate is larger for the cationic compounds with higher pK(a). For a phenol-paraquat TiO(2) system, paraquat degradation did not begin till near-complete phenol removal. Using,the Nafion-coated TiO(2), both phenol and paraquat degradations, , started simultaneously. Nevertheless, complete paraquat: removal: still-took longer than phenol.