Recyclable Fe₃O₄ Nanoparticles Responsive to Temperature for Heavy Oil Viscosity Reduction: Synthesis, Characterization, and Performance

Abstract

Responsive nanoparticles have attracted extensive attention because they can effectively switch between emulsification and demulsification, providing great convenience for the viscosity reduction and transportation of heavy oil. Based on the background, Fe 3 O 4 nanoparticles were prepared in this study by the coprecipitation method. N,N diethylacrylamide was grafted onto the surface of magnetic nanoparticles using reversible addition−fragmentation chain transfer polymerization to synthesize a temperature-responsive nanoparticle polymer. The morphology of it was observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), and its chemical structure was characterized by Fourier transform infrared (FTIR) spectroscopy and thermogravimetric (TG) analysis. The results show that the viscosity reduction rate was 94.7% at an oil/water ratio of 2:8 and a concentration of nanoparticles of 0.5 wt %. Meanwhile, it exhibited a decent viscosity reduction rate of about 77% at high salinity (10,000 mg/L). More importantly, the heavy oil emulsions could effectively achieve demulsification and recycle by cooling and applying a magnetic field. After 5 cycles, the viscosity reduction rate remained at more than 90%, showing its great potential of tuning the emulsion stability of heavy oil in a sustainable way.