Enhanced treatment of perfluoroalkyl acids in groundwater by membrane separation and electrochemical oxidation
Enhanced treatment of perfluoroalkyl acids in groundwater by membrane separation and electrochemical oxidation
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DOI：
10.1016/j.ceja.2020.100042
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发表时间：
2020-10
期刊：
影响因子：
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通讯作者：
Á. Soriano;C. Schaefer;A. Urtiaga
中科院分区：
文献类型：
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作者：
Á. Soriano;C. Schaefer;A. Urtiaga
本工作探讨了膜分离-电化学氧化耦合技术处理地下水中的多氟烷基酸和全氟烷基酸。一个过程系统工程方法的基础上建模和经验数据。对两种纳米过滤（NF 90）和反渗透（BW 30）膜进行了表征，用于处理含有PFOA、PFHpA、PFHxA、PFPeA和PFBA的全氟羧酸（PFCAs）的电解质（NaCl和CaSO 4）混合物，初始浓度各为10 µg L-1。膜表面电荷屏蔽和浓差极化对NF 90的性能产生负面影响，并选择了BW 30膜。采用掺硼金刚石阳极进行电化学氧化，处理添加了全氟辛烷磺酸和6：2 FTSA的全氟辛烷磺酸混合物，模拟先前预浓缩的进料和非预浓缩的进料条件。在20至350 A m−2的不同电流密度（J）下，全氟辛酸、全氟辛烷磺酸和6：2 FTSA的去除遵循一级表观动力学，尽管较短链的全氟辛烷磺酸最初表现出增加的趋势，因为它们同时发生电生成和降解。总的来说，在整个测试范围内，PFAA电解遵循一级动力学线性相关。出乎意料的是，PFAAs电解是更快的低导电性非预浓缩进料，这是归因于增强的直接电子转移机制，从较高的电池电压。对于99.9%的全氟辛酸去除率，通过四级反渗透级联和浓缩物的反渗透X处理，最大限度地降低了处理的具体总成本，使全氟辛酸达到美国环保局建议的饮用水健康咨询水平以下（全氟辛酸和全氟辛烷磺酸总和<70 ng L− 1）。
This work explores the treatment of poly- and perfluoroalkyl acids (PFAAs) in groundwater by coupling membrane separation and electrochemical oxidation (ELOX). A process system engineering approach based on modelling and empirical data was followed. Two nanofiltration (NF90) and reverse osmosis (BW30) membranes were characterized for treating an electrolyte (NaCl and CaSO4) mixture of perfluorocarboxylic acids (PFCAs) containing PFOA, PFHpA, PFHxA, PFPeA and PFBA with initial concentrations of 10 µg L−1each. Membrane surface charge shielding and concentration polarization negatively influenced NF90 performance, and the BW30 membrane was selected. Electrochemical oxidation with boron doped diamond anodes treated the PFCAs mixture amended with PFOS and 6:2 FTSA, emulating previously pre-concentrated feed and non-preconcentrated feed conditions. Working at different current densities (J) between 20 and 350 A m−2, the removal of PFOA, PFOS and 6:2 FTSA followed first order apparent kinetics, although shorter chain PFCAs initially showed increasing trends because of their simultaneous electrogeneration and degradation. Overall, ΣPFAA electrolysis followed first order kinetics linearly correlated toJin the full range of testing. Unexpectedly, PFAAs electrolysis was faster for the low conductive non-preconcentrated feed, a result that was ascribed to the enhanced direct electron transfer mechanism resulting from the higher cell voltage. For 99.9% PFAAs removal, the total specific cost of treatment was minimized using a cascade of four RO stages and ELOX treatment of the concentrate, to reach ΣPFAA below the Health Advisory Levels recommended by the USEPA in drinking water (<70 ng L−1sum of PFOA and PFOS).