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，以研究高温下矿物表面电荷、Zeta电位和在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，几乎没有关于这些参数的数据。将采用的方法是微电泳法，用于确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，通过放射性废物储存设施附近的地壳和热液地区的水流动。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至关重要，因为符号的变化可以发出从吸附到解吸的信号。了解吸附行为反过来又是预测污染物在地下迁移能力的关键。由于在高温条件下很难在原位评估矿物表面附近的离子位置，分子模拟是这项研究的实验部分的宝贵伙伴。计划对表面、水和反离子进行量子和经典的机械模拟。通过测量和模拟零点电荷和Zeta电势，将实验和理论联系起来，可以可靠地模拟表面附近的反离子结构。分子模拟提供了对可能发生的吸附量和控制离子在表面附近的动力学的吸附机制的洞察。

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.