The effect of formate brines on the emulsification of ionic, non-ionic, and enzymatic surfactants

Environmental concerns on contamination of subsurface porous media by toxic chemicals have motivated the petroleum industry to replace them with environmentally sustainable (green) and biodegradable alternatives. Green surfactants have emerged such as sugar, enzymatic, and microbial based surfactants. However, their emulsification with different oils and salinity conditions is unknown. In this study, different oil and brine systems are tested to measure interfacial properties, rheology and emulsification of Coco Glucoside (CG), a sugar-derived surfactant; and Greenzyme (GZ), an enzymatic-environmentally friendly surfactant. Emulsification with light and medium crude oil in the presence of sodium chloride and sodium formate brines gave similar results with 10-20 mu m average droplet size. However, medium-heavy crude oil with potassium formate produced 98 vol% emulsion with 3-6 mu m average droplet size. Most of the emulsions demonstrated a shear thinning behaviour apart from emulsions resulting from Coco Glucoside and medium-heavy crude oil in which a clear Newtonian behaviour was observed. (C) 2022 The Author(s). Published by Elsevier Ltd.