Effect of dispersants on the stability of calcite in non-polar solutions

Abstract

The surface modification of calcite has been widely used to improve the compatibility of calcite with non-polar solutions, but this method is complex, time-consuming and uneconomical. Thus, we propose to use dispersants for improving the compatibility of calcite with non-polar solutions and systematically study the dispersion effect and mechanism of various dispersants. Anionic bis (2-ethylhexyl) sulfosuccinate sodium (AOT), non-ionic sorbitol monooleate sodium (Span 80) and sorbitol trioleate (Span 85), cationic cetyltrimethylammonium bromide (CTAB), oleic acid (OA) and stearic acid (SA), are used to change the surface properties of calcite in nonpolar solutions. The results of sedimentation and rheology showed that the anionic dispersant AOT had the best dispersion performance and efficiency. All dispersants, except CTAB, can significantly improve the wettability of particle surface, and the calcite adsorbed AOT has the best hydrophobicity. XRD results showed that all dispersants were adsorbed on the surface of calcite. FT-IR and XPS confirmed that AOT adsorbed on the particle surface through the coordination between AOT and Ca2+. Zeta potential shows that the calcite system with anionic AOT has the highest surface charges, indicating that the strong electrostatic interaction is one reason of the stabilization of calcite particles. This work has guiding implications for the selection of dispersants to improve the compatibility of calcite with non-polar solvents.