Fluorinated polyether-coated Fe3O4-functionalized oxidized carbon nanotubes as a recyclable demulsifier for crude oil emulsion treatment

Abstract

Based on the excellent adsorption properties of carbon materials, a new magnetic nanodemulsifier was prepared in this study. First, carbon nanotubes were oxidized using a solvothermal method. Then, Fe₃O₄ was combined with oxidized carbon nanotubes using a one-pot method, and then grafted onto fluorine-containing polyether to prepare a magnetic composite demulsifier (Fe₃O₄@C–F) with good demulsification properties. The surface morphology of the composite demulsifier was analyzed using scanning electron microscopy (SEM). The structure of the composite demulsifier was characterized using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectrometry (XPS). The stability of the composite demulsifier was characterized using thermogravimetric analysis (TGA). Results showed that the oxidized carbon nanotubes and fluorinated polyether were successfully attached to Fe₃O₄. The experimental objective was to obtain a self-made crude oil emulsion. The demulsification test and recovery performance test were then performed, and the main factors affecting the demulsification performance of the demulsifier were investigated. Results showed that when the dosage was 800 mg L⁻¹, the temperature was 65 °C, the demulsification time was 90 min, and the pH value was 6. The demulsification effect of the Fe₃O₄@C–F magnetic composite demulsifier was the best, whereby the demulsification rate could reach 91.68%, and the oil–water interface was clear. Fe₃O₄@C–F had a magnetic response and could be recycled from the two-phase system six times under the action of an external magnetic field. Fe₃O₄@C–F is an efficient and environmentally friendly demulsifier that has important application value for enriching demulsification technology systems.