Iron reduction in nontronite-type clay minerals: Modelling a complex system

Geatches, Dawn L.; Clark, S. J.; Greenwell, H. Christopher

doi:10.1016/j.gca.2011.12.013

Cited by 13 publications

(10 citation statements)

References 49 publications

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“…This increase in total energy occurred because the screening density of the background charge decreased when the b -length was doubled; thus the positively charged monomers were able to interact more strongly. We found a similar effect due to a decrease in background charge density in a previous study . As increasing the cell size in the x and y directions did not reduce electrostatic interactions, the cell size described at the beginning of this section and shown in Figure was considered to be optimal within our method of like-with-like comparisons; that is, by reproducing identical environments in which only one variable changes (the monomers), we are effectively canceling-out the effect of the electrostatic interactions.…”

Section: Computational Details and Modelssupporting

confidence: 72%

Monomer Adsorption on Kaolinite: Modeling the Essential Ingredients

Geatches

Jacquet²,

Clark

et al. 2012

J. Phys. Chem. C

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In this study we investigate the fundamentals of a problem pertinent to the cement and concrete manufacturing industries, where clay minerals are pollutants of sands due to their capacity to adsorb additives designed to improve concrete workability. In this density functional theory (DFT) investigation we examine the adsorption of a selection of organic monomers, (e.g., CH 3 CH 2 CHOHCH 3 and (CH 3 ) 3 N + CH 2 CHOHCH 2 CH 3 ,Cl − ) on kaolinite (Al 2 Si 2 O 5 (OH) 4 ) to determine the nature of the basal surface/monomer interactions and, also, to determine whether the presence of an additional clay layer and separately water changes the nature of these interactions. We gauge these effects by examining their formation energies, structural configurations post relaxation, Mulliken charges, and molecular orbitals occupancies. The results show that interactions are predominantly electrostatic for charged monomers and H-bonding for noncharged and also that increasing the complexity of these systems does not change the nature of these interactions, but that it does change the strength of them as well as the potential chemical reactivity of these clay/monomer environments.

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Section: Computational Details and Modelssupporting

confidence: 72%

Monomer Adsorption on Kaolinite: Modeling the Essential Ingredients

Geatches

Jacquet²,

Clark

et al. 2012

J. Phys. Chem. C

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“…Their presence in the Dunino deposit was confirmed in a previous study (Matusik, 2010). A similar phenomenon was investigated and reported in the literature concerning the structures of clay minerals and iron oxides/hydroxides (Bose & Sharma, 2002;Pedersen et al, 2006;Geatches et al, 2012).…”

Section: Sorption Mechanismssupporting

confidence: 69%

The effect of acid activation and calcination of halloysite on the efficiency and selectivity of Pb(II), Cd(II), Zn(II) and As(V) uptake

Maziarz

Matusik

2016

Clay miner.

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The present study investigated the efficiency and mechanisms of aqueous Pb(II), Cd(II), Zn(II) and As(V) adsorption on natural (H), calcined (HC), and acid-activated halloysite (HA). The XRD and FTIR measurements indicated that the aluminosilicate framework was not affected by high-temperature treatment, in contrast to acid activation, which led to structural changes mainly in the tetrahedral sheet. The sorption of cations on H sample was low, though it was most effective for As(V). The X-ray photoelectron spectroscopy results suggested that removal of As(V) might be related to its reduction to As(III) involving oxidation of Fe(II) present in the mineral structure and/or iron minerals. The calcination enhanced halloysite sorption capacity for cations, while the As(V) sorption decreased. This was due to partial dehydroxylation and the subsequent formation of additional active sites. The acid treatment induced selective adsorption of Pb(II).

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“…[36][37][38][39][40] The aim of the present work is to provide, based on ab-initio electronic structure electronic states), vibrational (IR spectra) and dielectric (reflectance spectra) properties is presented. Special attention to the differences between Mg-pure and Fe-containing surfaces is also addressed.…”

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confidence: 99%

B3LYP Periodic Study of the Physicochemical Properties of the Nonpolar (010) Mg-Pure and Fe-Containing Olivine Surfaces

et al. 2014

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B3LYP periodic simulations have been carried out to study some physico-chemical properties of the bulk structures and the corresponding non-polar (010) surfaces of Mgpure and Fe-containing olivine systems; i.e, Mg2SiO4 (Fo) and Mg1.5Fe0.5SiO4 (Fo75). A detailed structural analysis of the (010) In contrast, the IR spectra of the surfaces are shifted to upper values and exhibit more bands compared to the corresponding bulk systems due to the shorter metal-O distances given in the coordinatively unsaturated metals and to symmetry reduction which brings non-equivalent motions between the outermost and the internal modes, respectively.

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Iron reduction in nontronite-type clay minerals: Modelling a complex system

Cited by 13 publications

References 49 publications

Monomer Adsorption on Kaolinite: Modeling the Essential Ingredients

Monomer Adsorption on Kaolinite: Modeling the Essential Ingredients

The effect of acid activation and calcination of halloysite on the efficiency and selectivity of Pb(II), Cd(II), Zn(II) and As(V) uptake

B3LYP Periodic Study of the Physicochemical Properties of the Nonpolar (010) Mg-Pure and Fe-Containing Olivine Surfaces

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