Xinjuan Hou

The geometric, electronic, and magnetic properties of Ag5X+ (X=Sc, Ti, V, Cr, Mn, Fe, Co, and Ni) clusters

Density functional theory calculations are performed on small cationic transition metal doped silver clusters, Ag5X+ (X = Sc, Ti, V, Cr, Mn, Fe, Co, and Ni) using the B3LYP and BP86 functionals. Several two-dimensional and three-dimensional isomers with the dopant at a high coordinated site are found to be close in energy. The relative energy of the isomers is checked with CCSD(T). The interaction between the dopant 3d electrons and the host is discussed by considering the density of states and the shape of the molecular orbitals. A large local spin magnetic moment on the dopant atom is predicted.

The direct adsorption of low concentration gallium from fly ash

ABSTRACT This study is mainly focused on the direct adsorption of low concentration gallium from the feed solution in pre-desilication soda-lime sintering process from coal fly ash. The adsorption kinetics, mechanism, and the influence of impurities, cyclic times, and eluant content are systematically researched. Results showed that the adsorption capacity was 2.89 mg/g resin with gallium concentration of 50 mg/L. The adsorption mechanism could be explained by the interaction between the oxygen atoms and nitrogen atoms of amidoxime group. Gallium was eluted efficiently by NaOH and Na2S mixed solution and the concentration could be reached to 2400 mg/L.

Molecular-Level Investigation of the Adsorption Mechanisms of Toluene and Aniline on Natural and Organically Modified Montmorillonite.

The present work reports the adsorption mechanisms of aniline and toluene in dry and hydrated montmorillonite (MMT-Na and MMT-Na-W) and tetramethylammonium-cation-modified MMT (MMT-TMA) as determined through density functional theory. These theoretical investigations explicitly demonstrate that cation-π interactions between Na(+)/TMA(+) cations and aromatics play the key role in adsorption of organics over MMT-Na and MMT-TMA. Weak hydrogen bonds between the H atoms of organics and basal O atoms of tetrahedral silicate also stabilize the location of organics. The combination of interactions between water and basal O atoms and between organics and water molecules in hydrated MMT complexes strengthens the adsorption of organics on MMT, resulting in higher formation energies in hydrated organically intercalated MMTs than in the corresponding dry complexes. The adsorption of organics also changes frontier orbital distributions and consequently promotes the preferential occurrence of reactions on the organics rather than on the MMT layers. These adsorption mechanisms predicted by theoretical investigation can be used to explicate the adsorption of aromatic organics on aluminosilicates with different external environment.

Comparison of the structures and electronic properties of sodalites containing alkali metals and alkali-earth metals and their hydrates

Abstract The effects of different alkali and alkali-earth metal ions on the electronic structures and properties of sodalite Mn[AlSiO4]6 (M-SOD) and their hydrates Mn[AlSiO4]6⋅8H2O (M=Li, Na, K, n = 6; M=Ca, n = 3) were studied using density functional theory method. Theoretical calculations predicted that the Al–O–Si bond angle and cation-framework oxide distance in sodalites with alkali metal cations are correlated with cell volumes. The reduced bandwidths in M-SOD (M=Li, Na and K) show that the inter-atomic orbital overlap in sodalites is weaker than those in the hydrate phases. Frontier molecular orbital analysis indicated that oxygen atoms in the frameworks and most metal ions of SOD and their corresponding hydrates exhibit high reactivity. The interactions existing in sodalites and hydrates were qualitative described. The calculated combination energies of metal ions with framework of sodalites are in the order of K+< Na+< Li+< Ca2+. This finding confirms the experimental observation for ion exchange.