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| Oxidative degradation of perfluorooctane sulfonate by a sono-activated persulfate system in an aqueous solution |
| Received:May 15, 2018 |
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| KeyWord:perfluorooctane sulfonate(PFOS);sono-activated;persulfate;kinetic characteristics;degradation mechanism |
| Author Name | Affiliation | E-mail | | LI Bing-zhi | Shanghai Academy of Environmental Sciences, Shanghai 200233, China | | | ZHU Jiang | Shanghai Academy of Environmental Sciences, Shanghai 200233, China | jzh@sjtu.edu.cn |
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| Abstract: |
| A sono-activated persulfate oxidative system was built to remove typical perfluorooctane sulfonate (PFOS). The effects of ultrasonic frequency, persulfate concentration, initial pH value, and the cavitation gas of the system on PFOS degradation rates were studied. The generated radicals and degradation intermediates of PFOS in this process were also captured and identified. The results indicated that 99.5% of 18.58 μmol·L-1 PFOS was degraded under a reaction temperature of 30℃, pH of 7.0, persulfate concentration of 0.93 mmol·L-1, ultrasonic frequency of 400 kHz, power of 100 W, ultrasonic density of 2.67 W·cm-2, and reaction time of 8 h. The PFOS degradation rate of the sono-activated persulfate system was 4.77 times higher than that of the single ultrasound and persulfate systems, which suggested a notable synergic effect. Further investigation also demonstrated that the apparent pseudo-first-order rate constants tended to increase with both the increase in ultrasonic frequency from 20 to 400 kHz and persulfate concentration from 18.58 to 930.0 μmol·L-1, but decreased with both the increase in the initial pH values from 3.00 to 11.03 and with the order of cavitation gases as argon, oxygen, nitrogen, and air. Electron spin trapping experiments showed that sulfate and hydroxyl radicals were involved in PFOS degradation. According to the seven types of degradation intermediates detected by UPLC-MS analysis, a tentative PFOS degradation pathway was proposed. |
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