Desorption of Asphaltenes from Silica-Coated Quartz Crystal Surfaces in Low Saline Aqueous Solutions

Abstract

The quartz crystal microbalance (QCM) was used to study desorption of asphaltenes from silica-coated quartz crystals upon exposure to various aqueous low saline solutions of different salt concentrations and cationic valency. Ultraviolet (UV) spectroscopy measurements confirmed desorption in selected experiments. The amount of desorption was related to the type and concentration of electrolyte and the sequence of injecting the electrolyte solutions. Initial desorption upon exposure to solutions with high ionic strength was likely due to repulsion between negatively charged sites acquired at the silica and the asphaltenes. During the injection of low saline aqueous solutions, a critical expansion of the diffuse double layer was required for desorption to occur. Comparatively lower desorption of asphaltenes was observed in the CaCl₂ solutions than in NaCl and seawater solutions.

Keywords:

• Asphaltenes
• desorption
• ionic strength
• low salinity
• quartz crystal microbalance

Acknowledgments

The authors would like to acknowledge the financial support from VISTA.

Notes

X = Na⁺, Ca²⁺, or SW.

X = Na⁺, Ca²⁺, or SW.