Selectivity and capacity of the core-shell demetalizers for removal of nickel and calcium ions from heavy oil through conventional electric desalination process

Abstract In this work, micron core–shell particles (P4VP@SiO2) are synthesized by chemically grafting poly(4-vinyl pyridine) (P4VP) onto the surface of SiO2 to explore their adsorption selectivity and capacity over nickel and calcium ions from heavy oil through conventional electric desalination process. FT-IR, TGA, elemental analysis (EA), SEM and TEM are employed to confirm the structure and grafting ratio of P4VP@SiO2. Then, the effects of various process conditions on nickel and calcium removal rates are investigated. It is found that, removal rates of nickel and calcium increase with increasing demetalizer concentration. Proper temperature and oil/water ratio favor two metals removal rates. Interestingly, both the experimental results and DFT calculations show that three demetalizers exhibit different adsorption selectivity and capacity for the two metals. The order of adsorption selectivity for nickel is PVP@SiO2 > PVIm@SiO2 > P4VP@SiO2(strong to weak). Moreover, the absorption capacity follows the sequence: P4VP@SiO2 > PVP@SiO2 > PVIm@SiO2, and the calcium absorption capacity of P4VP@SiO2 is much higher than the other two. The removal rates reach 68.2% for nickel and 62.2% for calcium by P4VP@SiO2, indicating that it possesses a great potential for removal of both nickel and calcium from heavy oil.