(104f) Characterizing the Electrochemically Enhanced Dissolution of Silica and Alumina in Alkaline Environments

Alumina (Al₂O₃) and silica (SiO₂) materials are prevalent in geological environments and complex materials used for device fabrication, structural materials, and catalysts. In each of these systems, the solid-liquid-solid interface plays a crucial role in determining material properties and interactions in aqueous environments, especially with regards to dissolution. In particular, both pressure solution and chemical-mechanical polishing demonstrate that the dissolution of alumina and silica materials can be drastically enhanced in aqueous environments however the cause of enhancement is highly debated. Dissolution enhancement in both of these systems share the same setup: asymmetric, or distinct, materials in close proximity in a saline, aqueous environment. In this work, we study the enhanced dissolution of alumina and silica in alkaline environments due to the presence of asymmetric surfaces. Using the surface forces apparatus (SFA) to characterize the enhanced dissolution of alumina and silica in proximity to muscovite mica surfaces, we found that the dissolution is enhanced to varying degrees depending on the relative surface potentials of the asymmetric surfaces. The impact of key parameters of the electrostatic double layer, such as the decay length and surface potential, were explored to provide insight into the electrochemical enhancement. Our findings highlight the importance of the asymmetric solid-liquid-solid interface and have implications in a variety of technological applications, such as structural materials development and chemical mechanical polishing.