论文标题
使用低成本石墨烯海绵电极的per和多氟烷基物质（PFA）的电化学降解
Electrochemical Degradation of Per- and Polyfluoroalkyl Substances (PFAS) using Low-cost Graphene Sponge Electrodes
论文作者
论文摘要
合成了硼龙掺杂的石墨烯海绵阳极，并应用于每次C4-C8的电化学氧化和多氟烷基物质（PFASS）。在低电导率电解度（1 ms cm-1）和一通流动模式下获得的去除效率在230 A M-2的阳极电流密度时，范围为16.7-67％，能耗为10.1+-0.7 kWh M-3。它们的去除归因于电吸附（7.4-35％）和电氧化（9.3-32％）。 C4-C8全烷基磺酸盐和酸的脱氟化效率为8-24％，因为仅在阳极表面被电吸收的一小部分。然而，相对于电氧化的部分，氟化物的回收率为74-87％，这表明一旦启动了PFA的降解，C-F键的裂解就非常有效。相对于电氧化级分的全氟烷基磺酸盐（91-98％）获得的几乎化学计量硫酸盐的回收率显示出有效的磺酸盐头组裂解。可吸附的有机氟化物（AOF）分析表明，剩余的部分放流的副产物在电流施用期间在石墨烯海绵阳极上被电吸收，并在电流关闭后将其释放到溶液中。这项概念证明的研究表明，发达的石墨烯海绵阳极能够键合裂解和PFA的脱氟。鉴于石墨烯海绵阳极对氯化物是电化学惰性的，即使在咸液溶液中也不会形成任何氯酸盐和高氯酸盐，因此开发的材料可能会解锁PFAS复合物废水和盐水的电化学降解。
Boron-doped, graphene sponge anode was synthesized and applied for the electrochemical oxidation of C4-C8 per and polyfluoroalkyl substances (PFASs). Removal efficiencies, obtained in low conductivity electrolyte (1 mS cm-1) and one-pass flow-through mode, were in the range 16.7-67% at 230 A m-2 of anodic current density, and with the energy consumption of 10.1+-0.7 kWh m-3. Their removal was attributed to electrosorption (7.4-35%), and electrooxidation (9.3-32 %). Defluorination efficiencies of C4-C8 perfluoroalkyl sulfonates and acids were 8-24% due to a fraction of PFAS being electrosorbed only at the anode surface. Yet, the recovery of fluoride was 74-87% relative to the electrooxidized fraction, suggesting that once the degradation of the PFAS is initiated, the C-F bond cleavage is very efficient. The nearly stoichiometric sulfate recoveries obtained for perfluoroalkyl sulfonates (91-98%) relative to the electrooxidized fraction demonstrated an efficient cleavage of the sulfonate head-group. Adsorbable organic fluoride (AOF) analysis showed that the remaining partially defluorinated byproducts are electrosorbed at the graphene sponge anode during current application and are released into the solution after the current is switched off. This proof-of-concept study demonstrated that the developed graphene sponge anode is capable of C-F bond cleavage and defluorination of PFAS. Given that the graphene sponge anode is electrochemically inert towards chloride and does not form any chlorate and perchlorate even in brackish solutions, the developed material may unlock the electrochemical degradation of PFAS complex wastewaters and brines.
