科研之友
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摘要
As one of the most reactive species, hydrated electron (e(aq)(-)) is promising for reductive decomposition of recalcitrant organic pollutants, such as perfluorooctane sulfonate (PFOS). In this study, PFOS decomposition using a vacuum ultraviolet (VUV)/sulfite system was systematically investigated in comparison with sole VUV and ultraviolet (UV)/sulfite systems. A fast and nearly complete (97.3%) PFOS decomposition was observed within 4 h from its initial concentration of 37.2 mu M in the VUV/sulfite system. The observed rate constant (kobs) for PFOS decomposition in the studied system was 0.87 +/- 0.0060 h(-1), which was nearly 7.5 and 2 folds faster than that in sole VUV and UV/ sulfite systems, respectively. Compared to previously studied UV/sulfite system, VUV/sulfite system enhanced PFOS decomposition in both weak acidic and alkaline pH conditions. In weak acidic condition (pH 6.0), PFOS predominantly decomposed via direct VUV photolysis, whereas in alkaline condition (pH > 9.0), PFOS decomposition was mainly induced by e(aq)(-) generated from both sulfite and VUV photolytic reactions. At a fixed initial solution pH (pH 10.0), PFOS decomposition kinetics showed a positive linear dependence with sulfite dosage. The co-presence of humic acid (HA) and NO3- obviously suppressed PFOS decomposition, whereas HCO3- showed marginal inhibition. A fewamount of short chain perfluorocarboxylic acids (PFCAs) were detected in PFOS decomposition process, and a high defluorination efficiency (75.4%) was achieved. These results suggested most fluorine atoms in PFOS molecule ultimatelymineralized into fluoride ions, and themechanisms for PFOS decomposition in the VUV/sulfite system were proposed.
- 出版日期2017-12-31
- 单位哈尔滨工业大学
