Synthesis Of Hydrophilically-modified Fe₃O₄ Nanoparticles And Research On Enhancing Separation Process Of Oil Sands

With the reduction of conventional fossil energy reserves around the world,the exploitation and utilization of unconventional oil is becoming an important part of energy supply.Recent reports show that the introduction of nanoparticles（NPs）can effectively enhance the recovery of unconventional oil.The base material of this research is superparamagnetic Fe₃O₄ NPs,which are further modified with hydrophilic group polyethylene glycol 600（PEG600）.The modification on one hand improves the dispersibility in water,on the other hand would reinforce the liberation process of bitumen from SiO₂ minerals by its hydrophilicity.Fe₃O₄ NPs were prepared by the coprecipitation method.They were further modified with PEG600-KH560（a kind of silane coupling agent）molecules by the hydroxyl substitution reaction on the surface to obtain PK-Fe₃O₄ NPs.Test results showed that the average size of the PK-Fe₃O₄ NPs was 15.89 nm,with the property of superparamagnetism.PK molecules accounted for about 30%of the total quality of PK-Fe₃O₄ NPs.PK-Fe₃O₄ NPs were stable under 200°C.PK-Fe₃O₄ nanofluids（NFs）were prepared by dispersing in alkaline water.The average particle size was 105.7 nm.PK-Fe₃O₄ NPs could be effectively recycled and evenly dispersed by controlling external magnetic field.PK-Fe₃O₄ NFs were applied to extract bitumen from Canadian oil sands by floatation experiment.The results showed that the introduction of PK-Fe₃O₄ NPs could increase the recovery of bitumen by around 12%and the quality ratio of bitumen to sand（B/S）by 0.17.As the NPs adsorbed a small amount of bitumen component,the recovery of bitumen and the B/S decreased with the increase of cycling times.PK-Fe₃O₄ NPs were recycled by magnetism.The recovery of NPs could increase to 70%with the increase of cycling times.The adsorption property of NPs on the surface of SiO₂ minerals was tested by QCM-D.Test results showed that PK-Fe₃O₄ NPs would adsorb on the surface of SiO₂minerals during the flooding of NFs.After alkaline cleaning of the surface,there was still a small amount of residual NPs.Results of contact angle tests showed that the adsorption could improve the wettability of SiO₂ minerals,thus enhancing bitumen recovery.The mechanism of bitumen liberation might be the wedge pressure caused by the regular arrangement of NPs.In addition,PK-Fe₃O₄ NPs could reduce the IFT of bitumen-water and improve the viscosity of NFs,thus promoting the transfer of bitumen to fluids.