A comparative study of surfactant adsorption by clay minerals

The adsorption of surfactants from aqueous solutions in porous media is essential in enhanced oil recovery (EOR) from oil reservoirs. Surfactant loss that is due to adsorption by the reservoir rocks weakens the efficiency of the chemical slurry that is injected and decreases the oil–water interfacial tension (IFT). This project investigated the effect of the mineralogical composition of adsorbents on adsorption. The experiments were conducted in batches. Adsorbents were composed of various combinations of quartz sand and clay minerals at various percentages and were exposed to nonionic and anionic surfactants. The amount of surfactant that was adsorbed was quantified by subtracting the concentration of surfactants after adsorption from the initial concentration. We observed a direct relationship between the adsorption of the nonionic surfactant and the amount of clay minerals in the adsorbents as the amount of surfactant that was adsorbed by the adsorbents increased when the percentage of clay minerals in adsorbents increased (from 5% to 20% in the mixture). The rank order of adsorption power of clay minerals for the nonionic surfactant was montmorillonite⪢illite>kaolinite. Adsorption of the anionic surfactant by all adsorbents was negligible.