MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China.
MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China.
J Environ Manage. 2023 Oct 15;344:118745. doi: 10.1016/j.jenvman.2023.118745. Epub 2023 Aug 8.
Efficient removal of perfluoroalkyl acids (PFAAs), especially short-chain ones, from contaminated water is of great challenge and is urgently called for so as to safeguard the ecosystem and human health. Herein, polypyrrole (PPy) functionalized biochar (BC) composites were innovatively synthesized by an in situ self-sacrificial approach to allow efficient capture of PFAAs with different chain lengths. Compared with conventional PPy-based composites synthesized by direct polymerization using FeCl as an oxidizing agent, PPy/BC composites were fabricated utilizing freshly generated Fe as an oxidizing agent from self-sacrificial FeO for pyrrole monomers in situ polymerizing on BC. As a result, with the support of BC and gradual release of Fe, PPy overcame its tendency to aggregate and became uniformly dispersed on BC, and meanwhile, PPy could well tailor the surface chemistry of BC to endow its positively charged surface. Consequently, the composites exhibited strong sorption capacities of 3.89 and 1.53 mmol/g for short-chain perfluorobutanoic acid (PFBA) and perfluorobutane sulfonic acid (PFBS), 2.55 and 1.22 mmol/g for long-chain perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), respectively, which were superior to those of pristine BC, commercial activated carbon, and anion exchange resins reported. Additionally, they could effectively remove 17 different classes of per- and polyfluoroalkyl substances (PFAS) (removal >95%) from actual PFAS-contaminated water, and the spent sorbent could be well regenerated and reused at least 5 times. An integrated analysis indicated that such an outstanding PFAA sorption performance on PPy/BC composites could be mainly attributed to surface adsorption enhanced by electrostatic attractions (anion exchange interaction) with the traditional hydrophobic interaction and pore filling of less contribution, particularly for short-chain analogues. These results are expected to inform the design of BC with greater ability to remove PFAS from water and the new sorbent could help water facilities comply with PFAS regulations.
高效去除水中的全氟烷基酸（PFAAs），尤其是短链 PFAAs，是一项极具挑战性的工作，迫切需要解决这一问题，以保护生态系统和人类健康。在此，通过原位自牺牲法创新性地合成了聚吡咯（PPy）功能化生物炭（BC）复合材料，以实现对不同链长的 PFAAs 的高效捕获。与传统的以 FeCl3 为氧化剂通过直接聚合合成的基于 PPy 的复合材料相比，PPy/BC 复合材料是利用新鲜生成的 Fe 作为氧化剂，从自牺牲的 FeO 中原位聚合吡咯单体在 BC 上制备的。结果，在 BC 的支持和 Fe 的逐渐释放下，PPy 克服了其聚集的趋势，均匀地分散在 BC 上，同时，PPy 可以很好地调整 BC 的表面化学性质，赋予其带正电荷的表面。因此，该复合材料对短链全氟丁烷酸（PFBA）和全氟丁烷磺酸（PFBS）具有 3.89 和 1.53 mmol/g 的强吸附能力，对长链全氟辛酸（PFOA）和全氟辛烷磺酸（PFOS）具有 2.55 和 1.22 mmol/g 的吸附能力，优于原始 BC、商业活性炭和阴离子交换树脂。此外，它们可以有效地从实际的 PFAS 污染水中去除 17 种不同类别的全氟和多氟烷基物质（PFAS）（去除率>95%），并且可以至少 5 次再生和重复使用用过的吸附剂。综合分析表明，PPy/BC 复合材料对 PFAAs 的出色吸附性能主要归因于静电吸引（阴离子交换相互作用）增强的表面吸附作用，而传统的疏水性相互作用和孔填充的贡献较小，尤其是对于短链类似物。这些结果有望为设计具有更强从水中去除 PFAS 能力的 BC 提供信息，并且新的吸附剂可以帮助水设施符合 PFAS 法规。
