Comparative study of PFAS treatment by UV, UV/ozone, and fractionations with air and ozonated air
Comparative study of PFAS treatment by UV, UV/ozone, and fractionations with air and ozonated air
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DOI：
10.1039/c9ew00701f
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发表时间：
2019-11-01
影响因子：
5
通讯作者：
Zhang, Jianhua
中科院分区：
文献类型：
--
作者：
Dai, Xiaodong;Xie, Zongli;Zhang, Jianhua
全氟烷基和多氟烷基物质及其衍生物是持久性有机化学品，对人类健康和环境造成重大不利影响。本文对紫外光、臭氧化空气分级、空气分级以及紫外光/臭氧联合处理去除PFAS进行了研究和比较。给水由消防泡沫合成，其含有多种全氟化和多氟化烷基物质。EGL专利的紫外线和臭氧组合设备被用来比较不同处理方法的性能，其中两个单元的钻机被用作台式设置和使用紫外线/臭氧组合处理的九个单元的钻机被用作试验钻机。试验结果表明，在紫外/臭氧联合处理中，随着空气流量和进水流量的增加，PFAS的去除率提高。在空气流速为30 L min（-1）和进料流速为1.4 L min（-1）（10 min停留时间）时，达到的最高PFAS去除效率为87%。不同的处理技术，包括紫外线，臭氧化空气分馏，空气分馏，进行了比较与紫外线/臭氧组合处理在20分钟的停留时间。紫外线单独去除16.8%的PFAS，这表明所有测试的最差性能。紫外线/臭氧组合处理去除73%的PFAS，空气分馏能够实现81%的PFAS去除。臭氧化空气分馏法对PFAS的去除率最高，可达95%以上，这是由于气泡中富含OH自由基。对于9个单元的试验装置，UV/臭氧组合处理实现了约79%的PFAS去除。然而，在处理过程中发生泡沫分离，这导致基于质量平衡的约4%的PFAS去除。因此，紫外线和臭氧联合处理的PFAS去除率为75%，这与台式装置的结果相似。所有处理导致至少一种类型的短链PFAS的浓度增加。当处理中发生气泡泡沫分离时，全氟烷基磺酸盐（PFSA）比全氟烷基羧酸盐（PFCA）更容易去除，因为PFSA比PFCA更疏水，这使其对气泡更有亲和力。此外，与长链PFAS相比，通过分馏技术去除短链PFAS要困难得多，这是由于分配因子随着碳数的减少而呈指数下降。
Per- and poly-fluorinated alkyl substances (PFAS) and their derivatives are persistent organic chemicals that result in significant adverse human health and environmental effects. In this paper, UV, ozonated air fractionation, air fractionation and combined UV/ozone treatment for PFAS removal were studied and compared. The feed water was synthesized from firefighting foam, which contained multiple per- and poly-fluorinated alkyl substances. Combined UV and ozone equipment patented by EGL were used to compare the performance of the different treatment methods, in which a two-unit rig was employed as a benchtop setup and a nine-unit rig using UV/ozone combined treatment was employed as a pilot rig. It was found from the benchtop tests that the PFAS removal efficiency was improved with the increase in air and feed flow rates in the UV/ozone combined treatment. The highest PFAS removal efficiency achieved was 87% at an air flow rate of 30 L min(-1) and a feed flow rate of 1.4 L min(-1) (10 min residence time). The different treatment techniques, including UV only, ozonated air fractionation, and air fractionation, were compared with the UV/ozone combined treatment at the residence time of 20 min. UV alone removed 16.8% PFAS, which showed the worst performance of all tests. The UV/ozone combined treatment removed 73% PFAS, and air fractionation was able to achieve 81% PFAS removal. Ozonated air fractionation showed the best PFAS removal efficiency, which was more than 95%, as a result of the enriched OH radicals in the gas bubbles. For the nine-unit pilot rig, the UV/ozone combined treatment achieved about 79% PFAS removal. However, foam fractionation occurred during the treatment, which led to approximately 4% removal of PFAS based on the mass balance. Therefore, the PFAS removal contributed by UV and ozone combined treatment was 75%, which was similar to the result from the benchtop rig. All treatment resulted in a concentration increase in at least one type of short-chain PFAS. When foam fractionation with gas bubbles occurred in the treatment, it was easier to remove perfluoroalkyl sulfonate (PFSA) than perfluoroalkyl carboxylate (PFCA) because PFSA is more hydrophobic than PFCA, which gives it more affinity for gas bubbles. In addition, in comparison with long-chain PFAS it is much more difficult to remove the short-chain PFAS by fractionation technologies, due to the partition factor declining exponentially with the reduced carbon number.