Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, United States.
Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States.
Environ Sci Technol. 2024 Apr 9;58(14):6425-6434. doi: 10.1021/acs.est.3c10584. Epub 2024 Mar 30.
Hydrated electron () treatment processes show great potential in remediating recalcitrant water contaminants, including perfluoroalkyl and polyfluoroalkyl substances (PFAS). However, treatment efficacy depends upon many factors relating to source water composition, UV light source characteristics, and contaminant reactivity. Here, we provide critical insights into the complex roles of solution parameters on contaminant abatement through application of a UV-sulfite kinetic model that incorporates first-principles information on photogeneration and reactivity. The model accurately predicts decay profiles of short-chain perfluoroalkyl acids (PFAAs) during UV-sulfite treatment and facilitates quantitative interpretation of the effects of changing solution composition on PFAS degradation rates. Model results also confirm that the enhanced degradation of PFAAs observed under highly alkaline pH conditions results from changes in speciation of nontarget scavengers. Reverse application of the model to UV-sulfite data collected for longer chain PFAAs enabled estimation of bimolecular rate constants (, M s), providing an alternative to laser flash photolysis (LFP) measurements that are not feasible due to the water solubility limitations of these compounds. The proposed model links the disparate means of investigating processes, namely, UV photolysis and LFP, and provides a framework to estimate UV-sulfite treatment efficacy of PFAS in diverse water sources.
水合电子（）处理工艺在修复包括全氟烷基和多氟烷基物质（PFAS）在内的难处理的水中污染物方面显示出巨大的潜力。然而，处理效果取决于许多因素，包括原水成分、紫外光源特性和污染物的反应性。在这里，我们通过应用包含光致生成和反应的第一性原理信息的紫外-亚硫酸盐动力学模型，为溶液参数对污染物去除的复杂作用提供了重要的见解。该模型准确预测了紫外-亚硫酸盐处理过程中短链全氟烷酸（PFAAs）的衰减曲线，并有助于定量解释改变溶液组成对 PFAS 降解速率的影响。模型结果还证实，在高碱性 pH 条件下观察到的 PFAAs 增强降解是由于非目标 清除剂的形态变化所致。将该模型反向应用于更长链 PFAAs 的紫外-亚硫酸盐数据，可估算双分子速率常数（，M s），这是替代由于这些化合物的水溶性限制而不可行的激光闪光光解（LFP）测量的一种方法。所提出的模型将研究 过程的不同方法（即紫外光解和 LFP）联系起来，并为估计不同水源中紫外-亚硫酸盐处理 PFAS 的效果提供了框架。
