Calculation of Entropy of Adsorption for Small Molecules on Mineral Surfaces
Calculation of Entropy of Adsorption for Small Molecules on Mineral Surfaces
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DOI：
10.1021/acs.jpcc.7b11860
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发表时间：
2018-04-19
影响因子：
3.7
通讯作者：
Andersson, M. P.
中科院分区：
文献类型：
--
作者：
Budi, A.;Stipp, S. L. S.;Andersson, M. P.
我们进行了密度泛函理论计算吸附在方解石，石英和高岭石矿物表面的有机小分子，并计算了吸附的熵变。我们的研究结果表明，熵贡献的自由能主要是独立的结合机制，但它是受表面覆盖度，分子大小，字符，和自由度。与弱键合分子的实验结果相比，密度泛函理论计算预测吸附的熵损失更高，这可以用作估计吸附到矿物表面的熵贡献的上限。该研究表明，吸附分子的熵和气相熵之间存在线性关系，可用于估计熵对矿物吸附自由能的贡献，而无需显式密度泛函理论计算，这是预测污染物和其他有机化合物在多孔介质（如土壤，含水层和油藏）中行为的重要一步。
We performed density functional theory calculations for small organic molecules adsorbed on calcite, quartz, and kaolinite mineral surfaces and calculated the entropy change as a result of adsorption. Our results demonstrate that the entropy contribution to the free energy is mainly independent of the mechanism of binding, but it is affected by surface coverage, molecule size, character, and degrees of freedom. Compared with experimental results for weakly bonded molecules, density functional theory calculations predict a higher loss of entropy as a result of adsorption, which can be used as the upper limit for estimating the entropy contribution for adsorption to a mineral surface. The study has demonstrated a linear relationship between the entropy of the adsorbed molecule and the gas phase entropy, which can be used to estimate the entropy contribution to the free energy of adsorption on minerals without explicit density functional theory calculations, which is an important step forward in predicting the behavior of contaminants and other organic compounds in porous media such as soils, aquifers, and oil reservoirs.