Probing the Interaction Mechanisms of Dodecane and Mica/Calcite: Implications for Oil Recovery

Abstract

Understanding the interfacial interaction mechanisms between oil and minerals is of vital importance in the applications of petroleum production and environmental protection. In this work, the interactions of dodecane with mica and calcite in aqueous media were investigated by using the drop probe technique based on atomic force microscopy. For the dodecane–mica interactions, the electrical double layer (EDL) repulsion dominated in 10 mM NaCl solution, and a higher pH facilitated the detachment of dodecane. The EDL interaction was diminished with an elevated NaCl concentration, and the van der Waals (vdW) attraction triggered the oil attachment on the mica surface. In the presence of Ca²⁺ and Mg²⁺, the EDL repulsion was weakened leading to a thinner water film, and the oil attachment occurred. For the dodecane–calcite interactions, large adhesions were observed under all of the solution conditions, mainly attributed to the ionic bridging by Ca²⁺ formed during calcite dissolution. At pH 4, CO₂ bubbles appeared on the calcite surface, resulting in a repulsive vdW interaction between dodecane and the surface, which hindered the adhesion. The calcite surface wettability was modified in high concentrations of NaCl, leading to a reduced adhesion with oil. The ionic bridging effect was promoted, and the adhesion was enhanced in 500 mM Ca²⁺ and Mg²⁺ solutions. At pH 10, the precipitates of Ca(OH)₂(s) and Mg(OH)₂(s) appeared on the calcite surface, which diminished the adhesion. Our results provided fundamental insights into the mechanisms of oil–water–mineral interactions, which contributed to the understanding and modulation of engineering processes in the enhancement of oil pollutant removal and oil recovery.