Abstract：
Layered double hydroxides (LDH) have been shown to be effective adsorbents, but their utility for the treatment of per- and polyfluoroalkyl substances (PFAS) in water has not been fully explored. In this study, the adsorption of 9 PFAS on hydrotalcite (HT), a type of LDH, was investigated using reaction solutions with environmentally relevant PFAS concentrations. The adsorption of individual PFAS by HT depended upon a range of factors, including the temperature used to pre-treat (i.e., calcine) the HT, aging conditions, and the presence of anions in the solution. HT calcined near 400 °C most effectively adsorbed PFAS, but its ability to adsorb PFAS was sensitive to storage conditions. The adsorption of CO2 and moisture from air, which likely resulted in the re-intercalation of CO32- into the interlayer regions of HT, was observed to reduce PFAS adsorption and may explain performance loss over time. The adsorption trend among 9 PFAS and the influence on this process by Cl-, NO3-, SO42-, and CO32- indicated that adsorption occurred via a combination of ion exchange, electrostatic attraction, and hydrophobic interactions, although the relative importance of each mechanism deserves further investigation. During this study, we also demonstrated for the first time that HT can be thermally regenerated at 400 °C without affecting its ability to adsorb PFOS and PFBA. Overall, our results suggest that HT may serve as an effective alternative for PFAS treatment.
摘要：
层状双氢氧化物（LDH）已被证明是有效的吸附剂，但是它们用于处理水中的全氟烷基和多氟烷基物质（PFAS）的效用尚未得到充分探索。在这项研究中,9PFAS在水滑石（HT）上的吸附，一种LDH,使用具有环境相关PFAS浓度的反应溶液进行了研究。HT对单个PFAS的吸附取决于一系列因素，包括用于预处理的温度(即，煅烧)HT，老化条件，以及溶液中阴离子的存在。在400°C附近煅烧的HT最有效地吸附PFAS，但其吸附PFAS的能力对储存条件敏感。从空气中吸附CO2和水分，这可能导致CO32-重新嵌入HT的夹层区域，观察到减少PFAS吸附，并可以解释性能随时间的损失。9PFAS之间的吸附趋势以及Cl-对这一过程的影响，NO3-,SO42-,和CO32-表明吸附是通过离子交换的组合发生的，静电吸引,和疏水相互作用，尽管每种机制的相对重要性值得进一步研究。在这项研究中,我们还首次证明HT可以在400°C下热再生，而不会影响其吸附PFOS和PFBA的能力。总的来说,我们的结果表明,HT可能是PFAS治疗的有效替代方案.
