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 150min 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 150min. However, Cl^- and SO₄^2- ions reduced the removal efficiency of PVA after 150min. 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 0.12gL^-1, an initial PVA concentration of 20mgL^-1, and an air flow rate of 400mLmin^-1, as measured after 150min.