Probing the Impact of Asphaltene Contamination on Kaolinite and Illite Clay Behaviors in Water and Organic Solvents: A Calorimetric Study

摘要

A detailed understanding of the impacts of trace compounds and asphaltene adsorption on the behavior of clays contributes to the development,of production processes for heavy oils and bitumen with lower environmental impacts, to the treatment of tailings from mined bitumen, and to the mitigation of impacts from oil spills in natural environments. Probes, such as solution calorimetry, are sensitive to species transfer to and from clay surfaces and outcomes can be interpreted unambiguously when supplemented with thermogravimetric analysis and scanning electron microscopy measurements. In this study, the effects of asphaltene coating on the enthalpy of solution of kaolinite and illite clays in toluene, n-heptane, and deionized water were investigated at 60 degrees C and atmospheric pressure. Asphaltene coating increases organic compound sorption but does not impact water sorption vis-a-vis uncoated clay particles or water displacement from clay particles by organic liquids as solvents or as trace contaminants in water. Experimental outcomes are interpreted using a quantitative mass and energy balance model framework that isolates terms for solvent and trace contaminant sorption/desorption and surface energy effects. Mechanistic and quantitative insights underlying the stability of asphaltene-coated clay dispersions in tailings ponds and the behaviors of these clays in diverse industrial and natural environments are discussed.