Chemical Research in Chinese Universities ›› 2016, Vol. 32 ›› Issue (1): 118-126.doi: 10.1007/s40242-016-5201-z

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Theoretical Study About Effects of H2O and Na+ on Adsorption of CO2 on Kaolinite Surfaces

WU Dinglu, JIANG Wen, LIU Xiaoqiang, QIU Nianxiang, XUE Ying   

  1. College of Chemistry, Sichuan University, Chengdu 610064, P. R. China
  • Received:2015-05-20 Revised:2015-06-02 Online:2016-02-01 Published:2015-07-22
  • Contact: XUE Ying E-mail:yxue@scu.edu.cn
  • Supported by:

    Supported by the National Basic Research Program of China(No.2011CB201202) and the National Natural Science Foundation of China(Nos.21173151, 21573153).

Abstract:

The density functional theory(DFT) was used to investigate the adsorptions of carbon dioxide(CO2) on kaolinite surfaces and the influences of Na+ and H2O on the adsorption. Both cluster and periodic models of kaolinite were considered. The calculated results indicate that stable complexes can be formed between adsorbed CO2 and the surfaces of kaolinite in the presence or absence of sodium cation and water molecule. The Al-O octahedral surface has a larger adsorption affinity for CO2 than the Si-O tetrahedral surface of kaolinite because the hydroxyl groups of kaolinite Al-O surface present more activity than the basal O atoms of the Si-O tetrahedral surface in the inter-molecular interactions. The existence of exchangeable sodium cations exerts the significant effect on the adsorption of CO2 with the dramatic increase of the adsorption energy, while the presence of water molecule decreases the adsorption strength insignificantly. The calculated Gibbs free energies of the adsorption reveal that the adsorptions of CO2 on all the investigated kaolinite surfaces are feasible thermodynamically in the gas phase. Surface free energy was calculated to provide the predictions of the surface stability as a function of temperature.

Key words: Carbon capture, storage, and utilization(CCSU), CO2, Kaolinite, Adsorption, Density functional theory