Battelle Memorial Institute, Columbus, OH 43201, USA.
Battelle Memorial Institute, Columbus, OH 43201, USA.
J Environ Manage. 2021 Jul 1;289:112439. doi: 10.1016/j.jenvman.2021.112439. Epub 2021 Apr 2.
Per- and polyfluoroalkyl substances (PFAS) are a large class of chemicals widely used for many commercial and industrial applications and have resulted in contamination at sites across globally. Pump-and-treat systems, groundwater extraction, and ex situ treatment using granular activated carbon (GAC) are being implemented, either in full or pilot scale, to treat PFAS-impacted groundwater and drinking water. The only current method of regenerating spent GAC is to reactivate it at temperatures greater than 1000 °C, which requires large amounts of energy and is quite expensive. This research focused on development and demonstration of an effective GAC regeneration technology using a solvent-based method for PFAS-laden GAC used in water treatment. Two different organic solvents (ethanol and isopropyl alcohol) with 0.5% and 1.0% ammonium hydroxide (NHOH) as a base additive were tested to determine the most effective regenerant solution to remove PFAS from the contaminated GAC. Based on column tests using laboratory-contaminated GAC with perfluorooctanoic acid (PFOA) and perfluorooctanoic sulfonate (PFOS), the solvent-base mix (SBM) of ethanol with 0.5% NHOH was found to be the optimum performing regenerant solution. The GAC life span assessment showed that solvent-regenerated GAC performed similar to virgin GAC without losing its optimal performance of PFAS sorption. Further, the solvent-regenerated GAC showed optimal performance even after four cycles of solvent regenerations tested using the optimum SBM. Average percent removal in laboratory-contaminated GAC using the optimum SBM was 65% and 93% for PFOS and PFOA, respectively. Four field-spent GAC samples were also regenerated using the optimum SBM. Percent removal from these samples was found to be in range of 55%-68%. The type of GAC used, level of contamination and type of PFAS present, water type and quality, and the presence of co-contaminants may have influenced the removal capacity. Distillation experiments have shown that it is feasible to concentrate the spent solvent prior to disposal, which reduces the amount of PFAS-contaminated solvent waste produced in regeneration cycles.
全氟和多氟烷基物质（PFAS）是一大类化学物质，广泛用于许多商业和工业应用，导致全球各地的场地受到污染。正在实施（或正在全面或试点规模实施）泵抽处理系统、地下水抽取和使用颗粒状活性炭（GAC）的异位处理，以处理受 PFAS 影响的地下水和饮用水。目前唯一的再生用过的 GAC 的方法是在高于 1000°C 的温度下使其再活化，这需要大量的能量并且非常昂贵。这项研究专注于开发和展示一种有效的 GAC 再生技术，该技术使用基于溶剂的方法用于处理水中的负载有 PFAS 的 GAC。测试了两种不同的有机溶剂（乙醇和异丙醇），并以 0.5%和 1.0%的氨水溶液（NHOH）作为基础添加剂，以确定从受污染的 GAC 中去除 PFAS 的最有效再生剂溶液。基于使用含全氟辛酸（PFOA）和全氟辛烷磺酸（PFOS）的实验室污染 GAC 的柱测试，发现乙醇与 0.5%NHOH 的溶剂基混合物（SBM）是性能最佳的再生剂溶液。GAC 寿命评估表明，溶剂再生的 GAC 表现与原始 GAC 相似，不会失去其对 PFAS 吸附的最佳性能。此外，即使在使用最佳 SBM 测试的四个溶剂再生循环之后，溶剂再生的 GAC 也表现出最佳性能。使用最佳 SBM 在实验室污染 GAC 中的平均去除率分别为 PFOS 和 PFOA 的 65%和 93%。还使用最佳 SBM 对四个现场使用的 GAC 样品进行了再生。从这些样品中的去除率在 55%-68%的范围内。所使用的 GAC 类型、污染程度和存在的 PFAS 类型、水类型和质量以及共存污染物的存在可能影响了去除能力。蒸馏实验表明，在处置之前浓缩用过的溶剂是可行的，这减少了再生循环中产生的受 PFAS 污染的溶剂废物的量。
