Kishimoto Naoyuki, Doda Koji
Faculty of Science and Technology, Ryukoku University, 1-5 Yokotani, Setaoe-cho, Otsu 520-2194, Japan E-mail:
Water Sci Technol. 2018 Jan;77(1-2):108-113. doi: 10.2166/wst.2017.526.
Vacuum ultraviolet (VUV) photolysis at the wavelength of 172 nm in a sulfate solution was introduced as a more efficient process for perfluorooctane sulfonate (PFOS) degradation than ultraviolet (UV) photolysis at 254 nm. The effects of pH and coexisting chemicals on VUV photolysis under the coexistence of 100 mM sulfate were investigated. VUV irradiation successfully degraded PFOS, and the degradation rate was 5.5 times higher than by UV photolysis. Direct VUV photolysis was inferred to mainly contribute to PFOS degradation. PFOS degradation by VUV irradiation was enhanced at pH less than 2 due to sulfate radicals generated via VUV photolysis of sulfate ions. Consequently, VUV photolysis was superior to UV photolysis for PFOS removal on both the removal rate and energy efficiency. However, the inorganic chemicals phosphoric acid and nitric acid strongly inhibited PFOS degradation, probably by masking PFOS from VUV rays by their VUV absorption. Accordingly, PFOS separation from inorganic materials such as phosphate and nitrate will be recommended for the application of VUV techniques for PFOS removal. In this research, organic solvent abstraction was inferred to be one of candidates for PFOS separation.
在硫酸盐溶液中，172 nm波长的真空紫外线（VUV）光解被认为是一种比254 nm紫外线（UV）光解更高效的全氟辛烷磺酸（PFOS）降解方法。研究了在100 mM硫酸盐共存下pH值和共存化学物质对VUV光解的影响。VUV辐照成功降解了PFOS，降解速率比UV光解高5.5倍。推断直接VUV光解是PFOS降解的主要原因。由于硫酸根离子通过VUV光解产生硫酸根自由基，在pH小于2时，VUV辐照对PFOS的降解作用增强。因此，在去除率和能源效率方面，VUV光解在去除PFOS方面优于UV光解。然而，无机化学物质磷酸和硝酸强烈抑制PFOS降解，可能是通过它们对VUV的吸收将PFOS与VUV射线屏蔽开来。因此，对于应用VUV技术去除PFOS，建议将PFOS与磷酸盐和硝酸盐等无机材料分离。在本研究中，推断有机溶剂萃取是PFOS分离的候选方法之一。
