School of Civil and Environmental Engineering, Cornell University, Ithaca, NY, 14853, USA.
Department of Chemistry, Northwestern University, Evanston, IL, 60208, USA.
Water Res. 2020 Sep 1;182:115950. doi: 10.1016/j.watres.2020.115950. Epub 2020 May 25.
Per and polyfluoroalkyl substances (PFASs) have raised great concern due to their ubiquity in aquatic environments, and adsorption technologies are among the most promising treatment solutions. This study investigated the key factors that influence the adsorption of anionic PFASs on conventional and emerging adsorbents. Batch adsorption experiments were conducted to evaluate the removal of 20 target PFASs at environmentally relevant concentrations by three different activated carbon (AC) materials and two different β-cyclodextrin polymers (CDPs). Experiments were conducted in Milli-Q water and in groundwater. Major physical properties of the adsorbents were measured, along with general water chemistry parameters for each groundwater sample. Principal component analysis (PCA) was subsequently employed to extract the important associations from the multivariate dataset. The distinct performances of ACs and CDPs were attributed to their different surface chemistry and the distinct nature of their adsorption binding sites. Hydrophobic interactions dominated PFAS adsorption onto ACs while CDPs mostly attracted anionic PFASs via favorable electrostatic interactions. ACs of a smaller average particle size performed better, with our data pointing to an increased external specific surface area as the likely reason. pH and the concentration of cations were the primary contributors to adsorption inhibition in groundwater. Higher pH values limit anionic PFAS adsorption by deprotonating the functional groups on adsorbent surfaces. The elevated levels of cations in some groundwater samples limited the effects of attractive electrostatic interactions. Knowledge of PFAS adsorption mechanisms gained from this study can be used to design more efficient adsorbents and to predict their performance under a range of environmental scenarios.
全氟和多氟烷基物质（PFASs）因其在水生环境中的普遍存在而引起了极大的关注，吸附技术是最有前途的处理解决方案之一。本研究调查了影响阴离子 PFASs 在常规和新兴吸附剂上吸附的关键因素。通过三种不同的活性炭（AC）材料和两种不同的β-环糊精聚合物（CDP），在环境相关浓度下进行了批量吸附实验，以评估 20 种目标 PFASs 的去除情况。实验在 Milli-Q 水和地下水进行。测量了吸附剂的主要物理性质，并测量了每个地下水样本的一般水化学参数。随后采用主成分分析（PCA）从多元数据集提取重要关联。AC 和 CDP 的不同性能归因于它们不同的表面化学性质和吸附结合位点的不同性质。疏水相互作用主导了 AC 对 PFAS 的吸附，而 CDP 主要通过有利的静电相互作用吸引阴离子 PFAS。平均粒径较小的 AC 表现更好，我们的数据表明增加的外部比表面积可能是原因。pH 值和阳离子浓度是地下水吸附抑制的主要因素。较高的 pH 值通过使吸附剂表面上的官能团去质子化来限制阴离子 PFAS 的吸附。一些地下水样本中较高水平的阳离子限制了吸引力静电相互作用的影响。从这项研究中获得的关于 PFAS 吸附机制的知识可用于设计更有效的吸附剂，并预测它们在一系列环境情况下的性能。
