Fabrication of N-(Amino-Ethyl)-Amino-Propyl Functionalized Magnetite Nanoparticles for Oil–Water Separation of Wastewater From Tertiary Oil Recovery

N-(amino-ethyl)-amino-propyl trimethoxy silane (AEAPTMS) is used to modify Fe₃O₄ with a one-pot coprecipitation method. Powder X-ray diffraction measurements show the spinel structure of magnetite nanoparticles. A high positive charge of +33.96 mV was obtained on the surfaces of modified magnetic nanoparticles, with the diameter ranging from 6.5 to 22.5 nm. The modified Fe₃O₄ was first applied to the treatment of wastewater from tertiary oil recovery. The obtained results indicated that the oil removal rate increased with the dosage of modified Fe₃O₄ and slightly increased with the separation time. The mechanism of modified Fe₃O₄ toward wastewater from tertiary oil recovery was attributed to the electrostatic interaction between negatively charged microemulsion oil in wastewater and the positively charged surfaces of magnetic nanoparticles.