Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Florida State University, 2525 Pottsdamer Street, Tallahassee, FL 32310, United States.
Department of Civil and Environmental Engineering, FAMU-FSU College of Engineering, Florida State University, 2525 Pottsdamer Street, Tallahassee, FL 32310, United States.
Waste Manag. 2023 Apr 15;161:104-115. doi: 10.1016/j.wasman.2023.02.030. Epub 2023 Mar 4.
Per- and polyfluoroalkyl substances (PFAS) are present in landfill leachate, posing potential challenges to leachate disposal and treatment. This work represents the first study of a thin-water-film nonthermal plasma reactor for PFAS degradation in landfill leachate. Of the 30 PFAS measured in three raw leachates, 21 were above the detection limits. The removal percentage depended on the category of PFAS. For example, perfluorooctanoic acid PFOA (C8) had the highest removal percentage (77% as an average of the three leachates) of the perfluoroalkyl carboxylic acids (PFCAs) category. The removal percentage decreased when the carbon number increased from 8 to 11 and decreased from 8 to 4. The effects of various landfill leachate components, including sodium chloride, acetate, humic acids, pH, and surfactants, had no or minor impacts (<30%) on PFOA mineralization in synthetic samples. This might be explained by the plasma-generation and PFAS-degradation mainly occurring at the gas/liquid interface. Shorter-chain PFCAs were produced as intermediates of PFOA degradation, and shorter-chain PFCAs and perfluorosulfonic acids (PFSAs) were produced as intermediates of perfluorooctanesulfonic acid (PFOS). The concentrations of the intermediates decreased with decreasing carbon number, suggesting a stepwise removal of difluoromethylene (CF) in the degradation pathway. Potential PFAS species in the raw and treated leachates were identified at the molecular level through non-targeted Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The intermediates did not show accurate toxicity per Microtox bioassay.
全氟和多氟烷基物质（PFAS）存在于垃圾渗滤液中，对渗滤液的处理和处置构成潜在挑战。本工作代表了用于降解垃圾渗滤液中 PFAS 的薄水膜非热等离子体反应器的首次研究。在三种原始渗滤液中测量的 30 种 PFAS 中，有 21 种超过检测限。去除率取决于 PFAS 的类别。例如，全氟辛酸（PFOA）（C8）作为三种渗滤液的平均值，具有最高的去除率（77%），属于全氟烷酸（PFCAs）类别。当碳数从 8 增加到 11 时，去除率降低，当从 8 减少到 4 时，去除率降低。各种垃圾渗滤液成分（包括氯化钠、醋酸盐、腐殖酸、pH 值和表面活性剂）对合成样品中 PFOA 矿化的影响无或较小（<30%）。这可以通过等离子体生成和 PFAS 降解主要发生在气/液界面来解释。作为 PFOA 降解的中间体，产生了较短链的 PFCAs，作为全氟辛烷磺酸（PFOS）的中间体，产生了较短链的 PFCAs 和全氟磺酸（PFSAs）。随着碳数的减少，中间体的浓度降低，表明降解途径中逐步去除二氟亚甲基（CF）。通过非靶向傅里叶变换离子回旋共振质谱（FT-ICR MS）在分子水平上鉴定了原始和处理后的渗滤液中的潜在 PFAS 物质。中间体在 Microtox 生物测定中没有显示出准确的毒性。
