Journals
  Publication Years
  Keywords
Search within results Open Search
Please wait a minute...
For Selected: Toggle Thumbnails
Adsorption Mechanism of Two Organic Molecules with Different Polarities on Calcite (104) Surface: Density Functional Theory Study
CHAI Rukuan, LIU Yuetian, YANG Li, ZHANG Yixin, XIN Jing, MA Jing
CHINESE JOURNAL OF COMPUTATIONAL PHYSICS    2020, 37 (2): 221-230.   DOI: 10.19596/j.cnki.1001-246x.8027
Abstract382)   HTML2)    PDF (11446KB)(1478)      
Density functional theory was employed to explore adsorption mechanism of benzoic acid and toluene molecules on calcite surface, and to analyze influence of polarity on the adsorption. It showed that benzoic acid was tilted adsorbed on CaCO3(104) surface in the form of undissociated molecules and in monodentate mode, while toluene was parallel adsorbed. Geometrical structure of organic molecules changed significantly during the adsorption, in which the deformation of benzoic acid was much greater than that of toluene. Meanwhile, electronic structure of the adsorption system was also changed. During the adsorption of benzoic acid, Ca-O ionic bond and H-O covalent bond were formed. However, there was only weak hydrogen bond between toluene and CaCO3(104) surface. Obviously, adsorption intensity of benzoic acid (polar molecule) on CaCO3(104) surface is greater than that of toluene (non-polar molecule). It provided theoretical support for EOR and mineral flotation engineering.
Reference | Related Articles | Metrics
Molecular Dynamics Simulation of Wettability of Calcite and Dolomite
CHAI Rukuan, LIU Yuetian, WANG Junqiang, XIN Jing, PI Jian, LI Changyong
CHINESE JOURNAL OF COMPUTATIONAL PHYSICS    2019, 36 (4): 474-482.   DOI: 10.19596/j.cnki.1001-246x.7868
Abstract605)   HTML10)    PDF (23678KB)(1606)      
We studied adsorption characteristics of oil-water system on calcite and dolomite surface with molecular dynamic simulation. To study wettability of calcite/dolomite surfaces, we analyzed equilibrium conformation, relative concentration, radial distribution function and adsorption energy of calcite/dolomite-oil/water system. Then, we proposed a two-step adsorption mechanism. It shows that dolomite-oil/water system is more easily to achieve thermodynamic stability and is more stable; A water film is formed on calcite and dolomite surfaces, which is a double-layer structure; There are interactions among oil molecules, water molecules and the crystal surface; Attraction of dolomite surface to oil and water molecules is stronger than calcite. Finally, we divided the adsorption process into two steps:Water molecules adsorbed on crystal surfaces form a tightly adsorbed layer under van der Waals forces, electrostatic forces and O(CaCO3,CaMg(CO3)2)-H(H2O) hydrogen bonds. In addition, the remaining water molecules move to the crystal surface form a diffusion layer under the influence of O(H2O)-H(H2O) hydrogen bonds. It reveals wettability formation and alteration mechanisms on calcite and dolomite surface, which paves a foundation of further enhance oil reovery.
Reference | Related Articles | Metrics