Degradation of Chlorinated Contaminants at Mineral - Water Interface: The Engineered vs. Natural Surfaces of Sulfide Materials

在这个由美国国家科学基金会化学部环境化学科学项目资助的项目中，来自德克萨斯理工大学（TTU）的Weile Yan教授和Kayleigh Millerick教授研究了一类表面硫化铁材料，这种材料可能有潜力在地下环境中降解氯化分子（特别是乙烯）。据推测，通过化学或生物手段控制铁金属（Fe(0)）的硫化产生的表面对氯化乙烯的反应性显著增强。本研究探讨了使用环境兼容的反应表面在原位减少持久性地下水污染物。本研究为本科生和研究生从事环境生物地球化学和修复的多学科研究提供了一个训练基地。这些发现被纳入了一门新的环境界面化学课程。此外，研究人员还开发了实验包，并通过TTU的科学丰富课程向K-12学生介绍地下水污染的主题。采用综合实验方法，探讨了不同条件下制备的硫化材料的化学性质与三氯乙烯（TCE）和过氯乙烯（PCE）在这些反应表面上的反应之间的关系。通过动力学和同位素研究，阐明了控制PCE和TCE在这些表面上降解速率和途径的关键因素。硫化层和Fe(0)相之间的界面为环境介质中的氧化钝化提供了持续的驱动力。研究了地表硫化铁和天然硫化铁在地下水环境中的转化，特别是相关生物地球化学过程的影响。这项研究促进了对氯化乙烯和活性表面之间相互作用的基本理解，这些表面要么是由工程干预引入的，要么是自然存在于地下环境中的。本研究探讨了地下水持久性污染物的原位减排，并培养本科生和研究生从事环境生物地球化学和修复的多学科研究。

In this project funded by the Environmental Chemical Sciences Program in the Chemistry Division at the National Science Foundation, Professors Weile Yan and Kayleigh Millerick from Texas Tech University (TTU) investigate a class of surface sulfided iron materials, which may have potential to degrade chlorinated molecules (specifically ethenes) in the sub-surface environment. It is hypothesized that controlled sulfidation of iron metal (Fe(0)) through chemical or biological means creates surfaces that have significantly enhanced reactivity towards chlorinated ethenes. This study explores the use of environmentally-compatible reactive surfaces for in situ abatement of persistent groundwater contaminants. This research provides a training ground for undergraduate and graduate researchers to engage in multidisciplinary investigations in environmental biogeochemistry and remediation. The findings are incorporated into a new course on Environmental Interfacial Chemistry. In addition, the investigators develop experiment kits and introduce the subject of groundwater contamination to K-12 students through science enrichment programs at TTU. The investigators take an integrated experimental approach to probe the relationship between the chemistry of the sulfided materials prepared under different conditions and the reactions of perchloroethene (PCE) and trichloroethene (TCE) on these reactive surfaces. Key factors controlling the rates and pathways of PCE and TCE degradation on these surfaces are elucidated through kinetic and isotopic investigations. The interface between a sulfided overlayer and an Fe(0) phase provides a sustained driving force against oxidative passivation in the environmental media. The transformation of surface sulfided iron and natural iron sulfides in groundwater environment, particularly under the influence of pertinent biogeochemical processes, are studied. This study advances the fundamental understanding of interactions between chlorinated ethenes and reactive surfaces that are either introduced by engineering intervention or naturally present in the subsurface environment. This study explores in situ abatement of persistent groundwater contaminants and trains undergraduate and graduate researchers to engage in multidisciplinary investigations in environmental biogeochemistry and remediation.