Adsorptive removal of oil drops from ASP flooding-produced water by polyether polysiloxane-grafted ZIF-8

A novel [email protected] demulsifier was developed through grafting branched polyether polysiloxane (PPS) molecules onto the ZIF-8 crystal. This demulsifier presented a rough surface structure with interconnected pores, large surface area and high hydrophobicity. When processing the simulated alkaline-surfactant-polymer (ASP) flooding produced water that contained 0.4 g L−1 oil, the demulsifier exhibited an oil removal rate of 90.03%, much higher than that of PPS (65.66%) and ZIF-8 (55.43%). The excellent oil removal rate was ascribed to its abilities to destabilize and coalesce the emulsified fine-sized oil droplets, including the demulsification of PPS and the adsorption of ZIF-8. An adsorption kinetics and isotherm study manifested that oil drops uptake onto ZIF-8 exhibited homogeneous and monolayer adsorption. A maximum adsorption capacity of 1753 mg g−1 was achieved due to the electrostatic and hydrophobic interaction between ZIF-8 and oil. The [email protected] demulsifier with unique oil adsorption properties offers great potential for oily wastewater treatment.