The Kinetics and Surface Chemistry of Mineral Corrosion

矿物腐蚀动力学和表面化学

• 批准号: 9302069
• 负责人: William Casey
• 金额: $ 17.52万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-07-01 至 1997-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9302069&HistoricalAwards=false
• 关键词: Kinetics; Surface; Chemistry; Mineral; Corrosion

We will continue our research into the mechanisms by which mineral surfaces interact with an aqueous solution during corrosion. In particular, we will determine the enthalpy contribution to the activation energy (Eexp) for mineral dissolution that arises from the rapid acid-base reactions which precede the rate-controlling step in dissolution. These acid-base reactions impart a distinct pH-dependence of the overall reaction. In research funded under EAR-910583, we showed that the enthalpy arising from acid-base reactions is the largest contribution to the Eexp (Casey and Sposito, 1992). This contribution varies considerably with pH and temperature, and is poorly constrained for silicate minerals. This research is important because atomistic models of the reaction energetics , such as molecular-orbital calculations (e.g., Casey et al., 1990), employ Eexp values as a gauge of the model accuracy. We also will indirectly probe the elementary step reaction controlling dissolution of simple minerals containing first-row transition metals. We predict that the affect of certain rate- enhancing ligands on the dissolution rates of these minerals will differ systematically and predictable with the delectronic structure of bonds to oxygen. This prediction arises from differences in the activation entropies and activation volumes of solvent exchange reactions around corresponding dissolved metal complexes. In previous work (e.g., Casey, 1991; Casey and Westrich, 1992) we found a close correspondence between reactivity trends for solvent-exchange reactions and metal removal from a dissolving oxide or orthosilicate mineral surface.

我们将继续研究 矿物表面与水溶液相互作用 腐蚀 特别地，我们将确定焓 对矿物溶解活化能（Eexp）的贡献 这是由快速的酸碱反应引起的， 溶解的速率控制步骤。 这些酸碱反应 赋予整个反应明显的pH依赖性。 在 在一项研究资助下，我们发现，焓 由酸碱反应产生的是对 Eexp（凯西和Sposito，1992）。 这种贡献各不相同 pH值和温度的影响很大，并且对于 硅酸盐矿物 这项研究很重要，因为原子论 反应能量学模型，如分子轨道 计算（例如，凯西等人，1990），采用Eexp值作为 模型的准确性。 我们还将间接地探讨基元步反应 控制含有第一排的简单矿物的溶解 过渡金属 我们预测，一定的利率的影响- 增强配体对这些矿物溶解速率的影响， 与电子系统不同且可预测 与氧键合的结构。 这一预测源于 激活熵和激活体积的差异 在相应溶解金属周围的溶剂交换反应 配合物 在以前的工作中（例如，凯西，1991年;凯西和 Westrich，1992年），我们发现了反应性之间的密切对应关系 溶剂交换反应和金属去除的趋势 溶解氧化物或正硅酸盐矿物表面。