Performance of UV/S₂O₈²⁻ process in degrading polyvinyl alcohol in aqueous solutions
2013
Lin, Chia-Chang | Lee, Li-Ting | Hsu, Ling-Jung
This study evaluates the performance of UV/S₂O₈ ²⁻ process in degrading polyvinyl alcohol (PVA) in aqueous solutions. The effects of pH, Na₂S₂O₈ 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 Na₂S₂O₈ dose and lower initial PVA concentration were associated with high degradation efficiency of PVA. Moreover, adding Cl⁻ and NO₃ ⁻ reduced the degradation efficiency of PVA. Radical scavenging tests adopted to identify predominant radicals reveal that SO₄ ⁻ was the predominant radical at pH 3, but OH was the predominant radical at pH 11. At pH 3, an Na₂S₂O₈ dose of 1.00mM, an initial PVA concentration of 20mg/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 0.3785min⁻¹, as measured after 10min. Comparison with heat/S₂O₈ ²⁻ process reveals that UV/S₂O₈ ²⁻ process can enhance the degradation of PVA at ambient temperature, suggesting that UV/S₂O₈ ²⁻ process would be alternative to degrade PVA in aqueous solutions.
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