Functionalized β-cyclodextrin with polyethyleneimine-coated Fe3O4 as a recyclable demulsifier for the efficient treatment of oily wastewater

The treatment of oily wastewater is an urgent problem in the environmental engineering fields. In view of the problems of secondary pollution and difficult recycling of existing demulsifier, a magnetic nanometer demulsifier Fe3O4 @PEI@ β-CD with high interfacial activity was synthesized. The chemical composition, structure, morphology and magnetic properties of Fe3O4 @PEI@ β-CD were characterized by FTIR, XRD, TEM, DLS and VSM. In addition, the effects of dosage, temperature, settling time and pH value on demulsification performance were detailly studied. The results showed that Fe3O4 @PEI@ β-CD can realize separation of oil from oily wastewater quickly and efficiently in a wide pH range at room temperature. And under acidic, neutral and alkaline conditions, the demulsification efficiency was more than 95 % when the dosage of Fe3O4 @PEI@ β-CD was 200 mg /L, the temperature was 45 ℃, and the settling time was 30 min. In the recyclability test, the demulsification efficiency did not decrease significantly after 11 times of recycling. Furthermore, the mechanism of demulsification was investigated through interfacial tension, zeta potential and optical microscopy. The finding suggests that Fe3O4 @PEI@ β-CD is an efficient, recyclable and environmentally friendly demulsifier that is expected to be used for oil-water separation.