Collaborative Research: Interfacial Water Restructuring: An Unrecognized Contribution to Mineral Surface Reactivity

有了这个奖项，化学系的环境化学科学计划资助教授杰弗里G。位于圣路易斯的华盛顿大学的Catalano和Sara E.这项研究是由爱荷华州大学的梅森教授进行的，他的目的是研究矿物表面附近的水分子排列如何影响污染物的吸附。吸附是环境界面的一个关键化学过程，直接控制污染物的命运和养分的可用性，是沉淀物的成核和生长，表面催化氧化还原反应，以及微生物和配体促进的氧化物矿物溶解的重要前体步骤。虽然吸附机制和表面电位对界面反应的影响是公认的，但对界面水的作用知之甚少。从这些研究中收集到的信息有望提供对重要环境过程中涉及的基本反应机制的深入了解，如污染物的命运，运输和降解，营养物质的生物利用度，二氧化碳封存和纳米颗粒动员。该项目将研究生、本科生和高中生实习生融入研究的进行中，并支持新的教育和推广活动。华盛顿大学的一名研究生将接受STEM生物学培训，然后为环境和人类健康课程开发新的积极学习活动。在爱荷华州的大学，每年的博物馆展览将准备教育K-12学生的社会重要性的地球化学表面science.The项目的目标是表征吸附剂诱导的矿物表面的界面水重构及其依赖于表面结构，表面充电，和流体组成。初步数据表明，砷酸盐吸附在氧化铝表面改变界面水的结构。批发重组发生在一个表面上，弱初始水秩序，而一个小的结构扰动，观察到强有序的表面上。界面水的这种结构转变预计会影响界面反应的能量学和动力学。本研究整合了砷酸盐吸附过程中铝和铁氧化物表面界面水行为的实验和计算研究。更具体地说，这项工作集成了基于同步加速器的表面晶体学技术，吸附等温线和动力学的实验室测量，密度泛函理论计算和从头算分子动力学模拟，以研究界面水的结构如何响应污染物砷的吸附，以及这些影响如何随矿物表面结构和充电而变化。 这项研究预计将揭示一个以前未被认识的机制，影响界面反应的能量学和动力学。

With this award, the Environmental Chemical Sciences Program of the Division of Chemistry is funding Professor Jeffrey G. Catalano of Washington University in St. Louis and Professor Sara E. Mason of the University of Iowa to investigate how the arrangement of water molecules near a mineral surface affects the adsorption of contaminants. Adsorption is a key chemical process at environmental interfaces that directly controls contaminant fate and nutrient availability and is an important precursor step in the nucleation and growth of precipitates, surface-catalyzed redox reactions, and microbial and ligand-promoted dissolution of oxide minerals. While adsorption mechanisms and the effect of surface potential on interfacial reactions are well established, little is known about the role of interfacial water. The information gleaned from these studies is expected to provide insight into fundamental reaction mechanisms involved in important environmental processes such as contaminant fate, transport, and degradation, nutrient bioavailability, carbon dioxide sequestration, and nanoparticle mobilization. This project integrates graduate students, undergraduate students, and high school student interns into the conduct of the research and supports new educational and outreach activities. A graduate student at Washington University will be trained in STEM pedagogies and then develop new active learning activities for a course on the environment and human health. At the University of Iowa, an annual museum exhibit will be prepared to educate K-12 students on the societal importance of geochemical surface science.The objective of this project is to characterize adsorbate-induced interfacial water restructuring on mineral surfaces and its dependence on surface structure, surface charging, and fluid composition. Preliminary data shows that arsenate adsorption on aluminum oxide surfaces alters interfacial water structure. Wholesale restructuring occurred on a surface with weak initial water ordering whereas a small structural perturbation was observed on a surface with strong ordering. Such structural transitions of interfacial water are expected to affect the energetics and kinetics of interfacial reactions. This investigation integrates experimental and computational studies of interfacial water behavior on aluminum and iron oxide surface during arsenate adsorption. More specifically, the work integrates synchrotron-based surface crystallography techniques, laboratory measurements of adsorption isotherms and kinetics, density functional theory calculations, and ab initio molecular dynamics simulations to study how the structure of interfacial water responds to the adsorption of the contaminant arsenic and how such effects vary with mineral surface structure and charging. This study is anticipated to reveal a previously unrecognized mechanism that affects the energetics and kinetics of interfacial reactions.