Effect of Hydrophobic and Hydrophilic Clays on Bitumen Displacement by Water on a Glass Surface

Abstract

Experiments were conducted to study the effect of hydrophobic and hydrophilic clays on bitumen displacement by an aqueous phase on a glass surface. A thin coating of bitumen on a glass surface displaced spontaneously in the inward radial direction upon exposure to an aqueous environment containing clay minerals. The initially circular bitumen disk took the shape of a spherical droplet. The dynamic and the static contact angles of bitumen on the glass surface were estimated by measuring the contact radius of bitumen with time. The dynamic and static contact angles in the presence of clay minerals are compared with the results when no clay is dispersed in the aqueous phase. The dynamic contact angle decreased in the presence of hydrophobic clays at higher pH when experiments were performed at 40 °C. The static contact angle also decreased in the presence of hydrophobic clays. The decrease in dynamic and static contact angles is found to be independent of clay concentrations over the range of the experimental study. The change in dynamic and static contact angles is small with increasing pH. Further, in the presence of hydrophobic clays, the dynamic and static contact angles did not decrease significantly at higher temperature, e.g., 80 °C. The effect of hydrophilic clays on the bitumen dynamic contact angle is not appreciable at different pHs and temperatures. The applicability of a previously proposed mathematical model based on the lubrication approximation for bitumen displacement is discussed. The dynamic contact angle predicted by the model is compared with experimental data for hydrophobic and hydrophilic clays at different pH conditions. The implication of the experimental results to hot water bitumen extraction is discussed.