College of Environment, Zhejiang University of Technology, Hangzhou 310014, China.
School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Environ Sci Technol. 2023 Jul 4;57(26):9811-9821. doi: 10.1021/acs.est.3c02039. Epub 2023 Jun 20.
Chloroform (CF) is a widely used chemical reagent and disinfectant and a probable human carcinogen. The extensive literature on halocarbon reduction with zerovalent iron (ZVI) shows that transformation of CF is slow, even with nano, bimetallic, sulfidated, and other modified forms of ZVI. In this study, an alternative method of ZVI modification─involving simultaneous sulfidation and nitridation through mechanochemical ball milling─was developed and shown to give improved degradation of CF (i.e., higher degradation rate and inhibited H evolution reaction). The composite material (denoted as S-N(C)-ZVI) gave synergistic effects of nitridation and sulfidation on CF degradation. A complete chemical reaction network (CRN) analysis of CF degradation suggests that O-nucleophile-mediated transformation pathways may be the main route for the formation of the terminal nonchlorinated products (formate, CO, and glycolic polymers) that have been used to explain the undetected products needed for mass balance. Material characterizations of the ZVI recovered after batch experiments showed that sulfidation and nitridation promoted the formation of FeO on the S-N(C)-ZVI particles, and the effect of aging on CF degradation rates was minor for S-N(C)-ZVI. The synergistic benefits of sulfidation and nitridation on CF degradation were also observed in experiments performed with groundwater.
氯仿（CF）是一种广泛使用的化学试剂和消毒剂，也是一种可能的人类致癌物。大量关于零价铁（ZVI）还原卤代烃的文献表明，即使使用纳米、双金属、硫化和其他改性形式的 ZVI，CF 的转化也很慢。在这项研究中，开发了一种 ZVI 改性的替代方法——通过机械化学球磨同时进行硫化和氮化，结果表明该方法可以提高 CF 的降解效率（即，更高的降解速率和抑制 H 逸出反应）。该复合材料（表示为 S-N(C)-ZVI）对 CF 降解具有氮化和硫化的协同作用。CF 降解的完整化学反应网络（CRN）分析表明，O-亲核试剂介导的转化途径可能是形成末端无氯化产物（甲酸盐、CO 和乙醇酸聚合物）的主要途径，这些产物已被用于解释质量平衡所需的未检测到的产物。批量实验后回收的 ZVI 的材料特性表明，S-N(C)-ZVI 颗粒上的硫化和氮化促进了 FeO 的形成，并且 S-N(C)-ZVI 对 CF 降解速率的老化影响较小。在地下水实验中也观察到了硫化和氮化对 CF 降解的协同益处。
