不同胺/铵阳离子在高岭石(001)面吸附的密度泛函计算

DFT calculations of different amine/ammonium cations adsorption on kaolinite(001) surface

为探索阳离子胺盐和季铵盐在高岭石表面的吸附机理,构建了CH6N+(伯胺阳离子)、C_2H_8N^+(仲胺阳离子)、C3H10N+(叔胺阳离子)及C4H12N+(季铵阳离子)4种不同胺/铵阳离子构型,并采用密度泛函理论对4种阳离子在高岭石(001)面的吸附进行模拟计算。模拟结果表明,4种阳离子CH6N+,C_2H_8N^+,C3H10N+及C4H12N+在高岭石(001)面都能发生稳定吸附,其较为稳定构型的吸附能分别-125.385,-126.154,-128.654和-109.711 k J/mol;但3种胺阳离子与季铵阳离子的吸附机理不同:胺阳离子在高岭石(001)面的吸附是静电引力和氢键的共同作用,季铵阳离子则只通过静电引力作用与高岭石(001)面发生吸附。静电引力作用是导致不同胺/铵阳离子在高岭石(001)发生吸附的主导作用。

To explore the adsorption mechanism of the cationic amine salts and quaternary ammonium salts on kaolinite surfaces, the authors built four configurations of amine/ammonium cations of CH6 N＋ （ Amine cation）, C2 Hs N＋ （ Second- ary amine cation）, Ca H10 N＋ （ Tertiary amine cation ） and C4H12N＋ （ Quaternary ammonium cation）. Also, the adsorp- tions of these four cations on kaolinite （001） surface were calculated using DFT （ Density functional theory）. The calculation results indicate that the four cations of CH6N＋, C2H8N＋, C3H10N＋ and C4H12N＋ could be favorably adsorbed on kaolinite （001） surface, and the adsorption energies of the more stable configuration of these four cations are 125. 385,-126. 154, - 128. 654 and - 109. 711 kJ/mol, respectively. However, the mechanism of three amine cations and quaternary ammonium cation adsorption on kaolinite （001） surface are different,where the amine cations are ad- sorbed on kaolinite （001） surfaces through both electrostatic attraction and hydrogen bonds while the quaternary ammonium cation only through the electrostatic attraction. The electrostatic attraction plays the main role in different a- mine-ammonium cations adsorption on kaolinite （001） surface.