Functional graphene oxide coated diatomite for efficient and recyclable demulsification of crude oil-in-water emulsion

The separation of micro-sized oil droplets from crude oil-in-water (O/W) emulsion is urgently required by petroleum industry and the environmental protection. Herein, we demonstrate a magnetically recyclable diatomite-graphene oxide (M-DM-GO) composite relying on the superior adsorption performance of graphene oxide (GO) and cost-effectiveness of diatomite (DM). Combining the improved positive surface charge by chemical grafting polyethyleneimine (PEI) on the GO surface, the as-prepared M-DM-GO exhibited high demulsification efficiency (Ed) of 96.8% for crude O/W emulsion with pH 6.0 at optimal dosage of 350 mg/L. Importantly, M-DM-GO displayed favorable demulsification performances under broaden pH conditions, suggesting its wide application scopes. Meanwhile, due to the magnetic response capability, M-DM-GO ensured efficient demulsification performance with Ed> 90% after 5 cycles. The efficiency, recyclability and wide pH application conditions make the M-DM-GO have universal application prospects in the management of crude O/W emulsion.