In this work, micron core–shell particles (P4VP@SiO 2 ) are synthesized by chemically grafting poly(4-vinyl pyridine) (P4VP) onto the surface of SiO 2 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@SiO 2 . 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@SiO 2 > PVIm@SiO 2 > P4VP@SiO 2 (strong to weak). Moreover, the absorption capacity follows the sequence: P4VP@SiO 2 > PVP@SiO 2 > PVIm@SiO 2 , and the calcium absorption capacity of P4VP@SiO 2 is much higher than the other two. The removal rates reach 68.2% for nickel and 62.2% for calcium by P4VP@SiO 2 , indicating that it possesses a great potential for removal of both nickel and calcium from heavy oil.
Mofan Li,Donghai Yang,Hongxu Zhong,Jie Pan,Liangyu Cai,Jiaxu Miao,Haotian Liu,Limin He
The rapid development of shale oil and offshore oil extraction has exacerbated brine contamination in crude oil, presenting challenges for conventional electric dehydration and desalination processes. Electric-magnetic coupling technology emerges as a promising alternative, while its underlying mechanisms and economic viability remain underexplored. In this study, we coupled a stabilized magnetic field with a high-frequency (greater than 1 kHz) pulsed alternating current electric field, enhancing the critical coalescence condition of salty droplets across a concentration range of 8.25 to 18.65 g·L −1 . Molecular dynamics simulations based on oil–water interface reveal that this enhancement is attributed to a reduction in the density and transport rate of surface charge on the droplets, influenced by ion electro enrichment and migration, ultimately allowing the electric field force to be insufficient against the capillary forces driving coalescence. Additionally, emulsion separation experiments show that the electric–magnetic coupling field increased separation efficiency by 33 % compared to the original electric field, achieving a rapid reduction of water content in high-salinity emulsions to 0.5 wt% within 20 min (includes 10 min of synchronized coupled field action). Furthermore, results of the techno-economic calculations based on our developed electric–magnetic coupling separation system indicate that the coupled-field system demonstrated a 8.26 % reduction in total costs due to lower energy consumption, highlighting its economic advantages in lower interest rate and high electricity price scenarios. Our findings provide novel insights into droplet coalescence dynamics and interfacial responses, paving the way for energy-efficient dehydration and desalination of crude oil.
Nickel in crude oil adversely affects the refining process for rapidly deactivating the hydrogenation and cracking catalysts. Polymer brushes bearing high-density ligands have shown promising nickel removal ability. In this work, submicron polybutadiene (PB) grafted by polyacrylamide (PAM@PB) was prepared and characterized by the transmission electron microscope, dynamic light scattering, and elemental analysis, which was also compared with the PB latex grafted by polyacrylic acid (PAA@PB) synthesized in our previous work. The nickel removal rates by both brushes were evaluated through the electric desalination process. The results show that the nickel removal capacity of PAA@PB is higher than that of PAM@PB. By the molecular dynamics simulations, the stretching and competitive chelation of polymer brush models PAA@PB-M and PAM@PB-M were investigated. Charged polyacrylic acid brushes usually have a higher thickness layer and a lower ligand density under the electrostatic repulsion and hydrogen bonding. The electrostatic interaction plays a more important role than the van der Waals interactions on nickel removal. PAA@PB-M is more attractive against Ni 2+ ions than PAM@PB-M. The inevitable formation of stable sandwiched π-π stacking structures between Ni 2+ ions and multiple porphyrin rings causes great difficulty in nickel removal during the electric desalination process. Adding protons to the oil phase can reduce the formation of the sandwiched structures and further improve nickel removal rates. In this paper, molecular dynamics simulation is innovatively applied to the mechanism of demetallization of polymer brushes, revealing the differences in structure and demetallization between charged and neutral polymer brushes, which provides guidance for the design of core–shell polymer brushes with high demetallization efficiency.
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