Experimental assessment of graphene oxide adsorption onto sandstone reservoir rocks through response surface methodology

This study mainly deals with the adsorption behavior of the graphene oxide (GO) onto sandstone which is an important factor for applying a material in chemical enhanced oil recovery methods. The combined effects of initial GO concentration, salinity and pH of the solution are assessed by adopting response surface methodology. The results show that the GO concentration has a stronger influence on the GO adsorption than those of the initial pH and salinity. The effect of pH on the GO adsorption becomes significant at high GO concentrations and low salinities. The Derjaguin-Landau-Verwey-Overbeek (DLVO) theory is applied to explain the observed trend of GO adsorption under various salinity and pH conditions. Reduction in the height of energy barrier and formation of a secondary minimum are responsible for increasing the GO adsorption at lower pH values and moderate salinities (1 wt.%). The contact angle measurement of the rock surface treated in GO solution at optimum conditions (GO concentration of 0.89 mg/mL, salinity of 5 wt.% and pH of 6.74) shows that the adsorbed GO can alter the wettability of sandstone from strongly oil wet (150 degrees) to intermediate conditions (90). (C) 2017 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.