Adsorption and photocatalytic degradation of polyvinyl alcohol in aqueous solutions using P-25 TiO 2

Abstract

This investigation evaluates the effectiveness of P-25 TiO 2 in removing polyvinyl alcohol (PVA) from aqueous solutions. The effects of pH, P-25 TiO 2 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 TiO 2 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 TiO 2 was attributable to adsorption and photocatalytic degradation, and the mechanism differed greatly from that with larger TiO 2 particles. Adding oxygen increased the removal efficiency of PVA, as measured after 150 min. However, Cl − and SO 4 2− ions reduced the removal efficiency of PVA after 150 min. NO 3 − 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 TiO 2 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.