铅组分活化锡石促进辛基羟肟酸吸附的量子化学计算研究

Quantum chemistry computational study of lead species promoting the adsorption of octyl hydroxamic acid on cassiterite

基于密度泛函理论,采用Vienna Ab-initio Simulation Package(VASP)对经Pb^(2+)或PbOH^(+)活化的锡石开展了量子化学计算研究,研究了铅组分对辛基羟肟酸在锡石(110)面上吸附的影响.计算结果表明:Pb^(2+)和Pb(OH)^(+)可自发地吸附于锡石(110)面.Pb^(2+)在锡石(110)面的吸附能力大于Pb(OH)^(+),Pb^(2+)的吸附能更负且Pb—O键长更短,与锡石(110)面的吸附作用更稳定.辛基羟肟酸通过羟肟酸基团中的N与锡石(110)面的Sn吸附连接成键,其吸附能为-191.17 kJ/mol,因空间位阻作用,辛基羟肟酸并未与锡石(110)面形成螯合吸附.然而,通过Pb^(2+)和Pb(OH)^(+)对锡石(110)面活化后,辛基羟肟酸通过其O与锡石(110)面上吸附的Pb^(2+)或Pb(OH)^(+)中的Pb之间有电子转移形成化学键,吸附能分别为-223.01和-279.95 kJ/mol.Pb^(2+)和Pb(OH)^(+)提高了辛基羟肟酸在锡石(110)面的吸附能力和稳定性.

Based on density functional theory,Vienna Ab-initio Simulation Package(VASP)was used to carry out the quantum chemistry research of cassiterite activated by Pb^(2+)or PbOH^(+),and the effect of lead composition on the adsorption of octyl hydroxamic acid on cassiterite(110)surface was studied.The results show that Pb^(2+)and Pb(OH)^(+)can spontaneously adsorb on cassiterite(110)surface.The adsorption of Pb^(2+)on cassiterite(110)surface is stronger than that of Pb(OH)^(+).The adsorption energy of Pb^(2+)is more negative and the Pb—O bond length is shorter,thus the adsorption between Pb^(2+)and cassiterite(110)surface is more stable.Octyl hydroxamic acid is adsorbed on cassiterite by chemical bond between N in hydroxamic acid group and Sn on cassiterite(110)surface,and its adsorption energy is-191.17 kJ/mol.Due to steric effect,octyl hydroxamic acid does not form chelate adsorption with cassiterite(110)surface.However,after the activation of cassiterite(110)surface by Pb^(2+)and Pb(OH)^(+),there is electron transfer and chemical bond formation between O of octyl hydroxamic acid and Pb adsorbed on cassiterite(110)surface,and the adsorption energy is-223.01 kJ/mol and-279.95 kJ/mol,respectively.Pb^(2+)and Pb(OH)^(+)improve the adsorption and stability of octyl hydroxamic acid on cassiterite(110)surface.