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The density functional theory (DFT) is applied to predict elemental mercury (Hg 0) adsorption on CoMnO 3 surface for the first time. GGA/PBE functional were selected to determine the potential Hg 0 capture mechanisms. The results show that Hg 0 has good affinity with CoMnO 3 surfaces with chemical adsorption. The adsorption energy of Hg 0-CoMnO 3 (1 0 0), Hg 0-CoMnO 3 (1 0 1) and Hg 0-CoMnO 3 (1 1 0) are-85.225,-72.305 and-70.729 kJ/mol, respectively. The Hg-Mn and Hg-Co mechanisms were revealed on low index surfaces. Hg 0 was oxidized to its valence state of 0.236 on Mn site in CoMnO 3 (1 0 0) surface. The Hg-Co interaction mechanism occurred on Hg 0-CoMnO 3 (1 0 1) and Hg 0-CoMnO 3 (1 1 0) with 0.209eand 0.189etransformation, respectively. The PDOS analysis shows that Hg-Mn interaction depends on the hybridization of Hg(s-and d-orbitals) and Mn (s-, p-and d-orbitals). However, Hg-Co interaction stems from sand d-orbitals of Hg, which only overlapping with d-and p-orbital of Co. Both the adsorption energy and electronic structure analysis indicated that CoMnO 3 catalyst performed excellent in Hg 0 oxidation. Exposing CoMnO 3 (1 0 0) is most favorable in Hg 0 control, which provides theoretical instruction on certain crystal plane synthesis in experiment.

Manganese dioxide formed in oxidation process by potassium permanganate exhibits promising adsorptive capacity which can be utilized to remove organic pollutants in wastewater. However, the structure variances of organic molecules lead to wide difference of adsorption efficiency. Therefore, it is of great significance to find a general relationship between removal rate of organic compounds and their quantum parameters. This study focused on building up quantitative structure activity relationship (QSAR) models based on experimental removal rate (r(exp)) of 25 organic compounds and 17 quantum parameters of each organic compounds computed by Gaussian 09 and Material Studio 6.1. The recommended model is rpre = -0.502-7.742 f(+)x + 0.107 E HOMO + 0.959 q(H(+)) + 1.388 BOx. Both internal and external validations of the recommended model are satisfied, suggesting optimum stability and predictive ability. The definition of applicability domain and the Y-randomization test indicate all the prediction is reliable and no possibility of chance correlation. The recommended model contains four variables, which are closely related to adsorption mechanism. f(+)x reveals the degree of affinity for nucleophilic attack. E HOMO represents the difficulty of electron loss. q(H(+)) reflect the distribution of partial charge between carbon and hydrogen atom. BO x shows the stability of a molecule.

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a b s t r a c tPotassium permanganate oxidation is one of the effective water treatment processes applied to remove organic compounds, but structure variances of organic molecules and different water conditions result in different effects. To provide a complete understanding of potassium permanganate oxidation, it is meaningful to develop some relationships between reaction rate constants of organic compounds and structure of molecules in three conditions (acid, neutral and alkaline). In this study, 22 diverse organic compounds were measured for the reaction rate and Quantitative Structure Activity Relationship (QSAR) models were developed based on reaction rate constants of organic substances and 17 quantum descriptors. Quantum chemical descriptors were obtained by using Gaussian 09 and Material Studio 6.1, including μ, EB3LYP, q(CH + ), q(C -), q(H + ), E LUMO , E HOMO , bond order and Fukui indices. A set of 18 compounds were used as training set to develop models and 4 compounds were used as test set for external validation. Three optimal models were selected in three conditions, respectively. In the models, energy of the highest occupied molecular orbital (E HOMO ) and Fukui indices appeared in all the conditions, indicating the two quantum descriptors play the important role during the oxidation process. Based on the evaluation criteria, model 4 in the acid condition was recommended and exhibited optimum stability and predictive ability. The equation of model 4 is ln k' = 0.53 + 0.22 μ + 14.26 E HOMO + 4.89 q(H + ) -18.21 f(0) x , the results also indicate that the dipole moment (μ) is much more closely related to the value of ln k' than other quantum descriptors in potassium permanganate oxidation process.