Preparation of a recyclable demulsifier for the treatment of emulsified oil wastewater by chitosan modification and sodium oleate grafting Fe3O4

Abstract In this study, to deal with the problem of emulsified oil contamination, Fe3O4 magnetic nanoparticle (MNP) was synthesized by thermal solvent method, then chitosan (CS) was applied to the surface of Fe3O4 to form Fe3O4@CS and sodium oleate (NaOL) was grafted onto the surface of Fe3O4@CS. A novel and environmentally friendly material Fe3O4@CS@NaOL MNP was synthesized. Synthetic MNP that is superparamagnetic and superhydrophobic which is used as a recyclable demulsifier to treat emulsified oil wastewater and its demulsification performance was evaluated. Especially, the effects of pH, demulsifier dosage and salt concentration on oil separation efficiency have been studied detailedly. The results show that the light transmittance of the emulsified wastewater increases to the highest when Fe3O4@CS@NaOL is added 400 mg/L. In addition, the new synthetic material has at least 8 cycle life and nearly no impact on demulsification performance. What’s more, the new synthetic material has at least 8 cycle life and nearly no impact on demulsification performance. In addition, the demulsification mechanism was also explored. The results indicate that the emulsified oil is effectively attached to Fe3O4@CS @NAOL under acidic and neutral conditions by electrostatic attraction. Especially after the introduction of NaOL, demulsification performance has been improved obviously. In conclusion, its preparation method is simple and easy to recycle. It provides a new feasible way to make a new demulsifier for the treatment of emulsified oil wastewater.