Adsorption of Cations on Mineral-Aqueous Solution Interface at Elevated Temperatures

Kubicki/ lvovear -0073722实验和分子模拟将并行进行，以检查矿物表面电荷，zeta电位和在高温水溶液中的吸附行为。许多研究小组目前正在研究这些现象；然而，在高达300摄氏度的高温下，这些参数几乎没有数据存在。所采用的方法是微电泳测定氧化物颗粒的电迁移率。本研究选用的矿物为刚玉和锆石。在本研究的温度范围内，在放射性废物储存设施附近和热液区，水流通过地壳。表面电荷和zeta电位随温度的变化对于预测离子的吸附行为是至关重要的，因为符号的变化可以表明从吸附到解吸的转变。了解吸附行为是预测污染物在地下迁移能力的关键。由于在高温条件下难以原位评估矿物表面附近离子的位置，分子模拟是本研究实验部分的有价值的伴侣。计划对表面、水和反离子进行量子和经典力学模拟。通过测量和模拟零点电荷和ζ电位，将实验和理论联系起来，可以可靠地模拟表面附近反离子的结构。分子模拟提供了对可能发生的吸附量和控制表面离子动力学的吸附机制的深入了解。

Kubicki/LvovEAR-0073722Experiments and molecular simulations will be performed in parallel to examine the behavior of mineral surface charge, zeta potential and adsorption in aqueous solutions at elevated temperatures. Numerous research groups are currently working on these phenomena; however, almost no data exists for these parameters at elevated temperatures up to 300 degrees C. The method to be employed is microelectrophoresis for determination of electrical mobilities of oxide particles. The minerals chosen for this study are corundum and zircon. Water flow through the crust near radioactive waste storage facilities and in hydrothermal areas occurs in the temperature range of this study. Knowledge of the surface charge and zeta potential with temperature are critical for predicting adsorption behavior of ions because a change in sign can signal a shift from adsorption to desorption. Understanding adsorption behavior is in turn key to the ability to predict the migration of contaminants in the subsurface. Due to difficulties in assessing the positions of ions near a mineral surface in situ under high temperature conditions, molecular simulations are a valuable companion to the experimental component of this research. Both quantum and classic mechanical simulations of surfaces, water and counterions are planned. By linking experiment and theory via the measured and simulated points-of-zero charge and zeta potentials, the structure of counter-ions near a surface may be reliably modeled. Molecular simulations provide insight into the amount of adsorption likely to take place and the mechanisms of adsorption that control the kinetics of ions near surfaces.