Preparation of Graphene Oxide/Attapulgite Composites and Their Demulsification Performance for Oil-in-Water Emulsion

In this study, attapulgite (AT) and graphene oxide (GO) nanosheets were grafted together via a silane coupling agent to synthesize attapulgite-graphene oxide (AT-GO) composites and apply them to remove the emulsified oil from the oily wastewater. The structure and morphology of the AT-GO composites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, zeta potential measurements, and transmission electron microscopy. The amphiphilicity of the AT-GO composites was evaluated by visual observation of their distribution in the oil-water mixture. The results showed that the AT-GO composites have been successively prepared and have good amphiphilic and interfacial activity. The effects of the pH, demulsifier dosage, temperature, and the mass ratio of AT and GO (R-A/G) in the composites on the demulsification performance of AT-GO were studied. It was found that the demulsification process could be completed efficiently and quickly at room temperature. Under optimal demulsification conditions, the demulsification efficiency is above 95%. The demulsification mechanism was studied and discussed. It is believed that the interaction behavior between the AT-GO material and the emulsified molecules of asphaltenes is a key for the demulsification. Once the nanoparticles are combined with the emulsified molecules, the external stirring, vibration, and other mechanical actions provide them enough kinetic energy to destroy the protective film at the oil/water interface and then promote the merging of dispersed oil droplets to realize the oil-water separation.

Automated summary

In this study, AT-GO composites were successfully prepared and showed good demulsification performance, with a demulsification efficiency above 95% at room temperature. The interaction behavior between the AT-GO material and emulsified molecules of asphaltenes was found to be key to the demulsification process.