Performance of UV/S2O82− process in degrading polyvinyl alcohol in aqueous solutions

Abstract

Abstract This study evaluates the performance of UV/S 2 O 8 2− process in degrading polyvinyl alcohol (PVA) in aqueous solutions. The effects of pH, Na 2 S 2 O 8 dose, initial PVA concentration, and addition of inorganic anions on the degradation efficiency of PVA were determined. The degradation efficiency of PVA followed the order pH 3 > pH 7 > pH 11. Additionally, higher Na 2 S 2 O 8 dose and lower initial PVA concentration were associated with high degradation efficiency of PVA. Moreover, adding Cl − and NO 3 − reduced the degradation efficiency of PVA. Radical scavenging tests adopted to identify predominant radicals reveal that SO 4 − was the predominant radical at pH 3, but OH was the predominant radical at pH 11. At pH 3, an Na 2 S 2 O 8 dose of 1.00 mM, an initial PVA concentration of 20 mg/L, and a temperature of 25 °C, the degradation efficiency of PVA in the absence of inorganic anions was 97% with the observed degradation rate coefficient of 0.3785 min −1 , as measured after 10 min. Comparison with heat/S 2 O 8 2− process reveals that UV/S 2 O 8 2− process can enhance the degradation of PVA at ambient temperature, suggesting that UV/S 2 O 8 2− process would be alternative to degrade PVA in aqueous solutions.