Adsorption and photocatalytic degradation of polyvinyl alcohol in aqueous solutions using P-25 TiO2

This investigation evaluates the effectiveness of P-25 TiO2 in removing polyvinyl alcohol (PVA) from aqueous solutions. The effects of pH, P-25 TiO2 dosage, initial PVA concentration, and addition of oxygen and inorganic anions on the removal efficiency of PVA were studied experimentally. The results importantly indicate that lower pH, higher P-25 TiO2 dosage, and lower initial PVA concentration were associated with high removal efficiency of PVA during 150 min of operation. The observed behavior reveals that the removal of PVA using P-25 TiO2 was attributable to adsorption and photocatalytic degradation, and the mechanism differed greatly from that with larger TiO2 particles. Adding oxygen increased the removal efficiency of PVA, as measured after 150 min. However, Cl- and SO42- ions reduced the removal efficiency of PVA after 150 min. NO3- ions did not affect the removal efficiency of PVA over such a period. In the absence of inorganic anions, around 100% of PVA was removed at pH 5, with a P-25 TiO2 dosage of 0.12 g L-1, an initial PVA concentration of 20 mg L-1 and an air flow rate of 400 mL min(-1), as measured after 150 min. (C) 2011 Elsevier B.V. All rights reserved.