Synthesis and Evaluation of CoFe2O4–Chitosan Nanoparticles in Enhanced Oil Recovery

Abstract

Chitosan nanoparticles with magnetic properties can be potentially used as separation materials in the adsorption of oil for enhanced oil recovery. Different from traditional surfactants, the novel magnetic CoFe2O4–chitosan nanoparticles have the advantages of excellent biodegradation and a high level of controllability. The CoFe2O4–chitosan nanoparticles with core–shell structure were prepared successfully. The images of transmission electron microscopy and scanning electron microscopy showed that the cube-shaped magnetic CoFe2O4 particles were encapsulated by the spherical chitosan nanoparticles. The sizes of the CoFe2O4–chitosan nanoparticles were all below 100 nm. The saturated magnetization of the CoFe2O4–chitosan nanoparticles could reach 80 emu/g and showed the characteristics of superparamagnetism at the same time. The evaluation of the interfacial properties of the product showed that the interfacial tension between crude oil and water could be reduced to ultra-low values—as low as 10−3 mN/m—when magnetic CoFe2O4–chitosan nanoparticle was used in several blocks in the Shengli Oilfield without other additives. Meanwhile, the magnetic CoFe2O4–chitosan nanoparticles possessed good salt-resisting capacity.