Competitive adsorption of arsenate and phosphate onto calcite; experimental results and modeling with CCM and CD-MUSIC

Sø, Helle Ugilt; Postma, Dieke; Jakobsen, Rasmus; Larsen, Flemming

doi:10.1016/j.gca.2012.06.021

Cited by 46 publications

(18 citation statements)

References 49 publications

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“…A minor reaction occurs at the calcite surface in agreement with adsorption studies of arsenate onto the surface of calcite by Sø et al (2012) and Yokoyama et al (2012). When phosphate is present in the solution, the replacement of calcite by As-bearing apatite takes place rapidly within a few hours (Fig.…”

Section: Apatite Structure Is the Key For Arsenic Incorporationsupporting

confidence: 76%

Complex mineral zoning patterns caused by ultra-local equilibrium at reaction interfaces

Borg

Liu

Pearce

et al. 2014

Geology

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Section: Apatite Structure Is the Key For Arsenic Incorporationsupporting

confidence: 76%

Complex mineral zoning patterns caused by ultra-local equilibrium at reaction interfaces

Borg

Liu

Pearce

et al. 2014

Geology

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“…For a detailed discussion of the CD-MUSIC model for calcite and its sensitivity to the different parameters and assumptions, please see Wolthers et al (2008). Recently, the capacitance values have been refined in an otherwise successful application of the CD-MUSIC model to arsenic sorption data for calcite (Sø et al, 2010 In the derivation of the equations for calcite growth, we adopt most assumptions made by Zhang and Nancollas (1998). The assumption that the overall detachment frequencies for anions and cations are the same, however, does not hold for calcite as the net detachment frequency of (bi-)carbonate is related to the solubility product, as will be shown in the next section.…”

Section: Conceptual Approachmentioning

confidence: 99%

Calcite growth kinetics: Modeling the effect of solution stoichiometry

Wolthers

Nehrke

Gustafsson

et al. 2012

Geochimica et Cosmochimica Acta

132

160

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Until recently the influence of solution stoichiometry on calcite crystal growth kinetics has attracted little attention, despite the fact that in most aqueous environments calcite precipitates from non-stoichiometric solution. In order to account for the dependence of the calcite crystal growth rate on the cation to anion ratio in solution, we extend the growth model for binary symmetrical electrolyte crystals of Zhang and Nancollas (1998) by combining it with the surface complexation model for the chemical structure of the calcite-aqueous solution interface of Wolthers et al. (2008). To maintain crystal stoichiometry, the rate of attachment of calcium ions to step edges is assumed to equal the rate of attachment of carbonate plus bicarbonate ions. The model parameters are optimized by fitting the model to the step velocities obtained previously by atomic force microscopy (AFM, Teng et al., 2000;Stack and Grantham, 2010). A variable surface roughness factor is introduced in order to reconcile the new process-based growth model with bulk precipitation rates measured in seeded calcite growth experiments. For practical applications, we further present empirical parabolic rate equations fitted to bulk growth rates of calcite in common background electrolytes and in artificial seawater-type solutions. Both the process-based and empirical growth rate equations agree with measured calcite growth rates over broad ranges of ionic strength, pH, solution stoichiometry and degree of supersaturation.

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“…The presence of dissolved organic matter could also be taken into account in studying anion adsorption in natural samples, because it can compete for adsorption sites or supply a negative charge [11,12]. The presence of other ions may also exert competitive or synergistic effects on the adsorption, as occurs with arsenate [13] and calcium [14], respectively.…”

Section: Introductionmentioning

confidence: 99%

Modeling oxyanion adsorption on ferralic soil, part 1: Parameter validation with phosphate ion

Pérez

Antelo

Fiol

et al. 2014

Enviro Toxic and Chemistry

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Surface complexation models have proved to be valuable tools for predicting processes that occur at the solid-solution interface. Use of such models has become more widespread and nowadays more complex systems are studied, in an attempt to explain processes such as the competition between different species for mineral surfaces and the effect of the presence of organic matter. The aim of the present study was to analyze the mobility of phosphate in ferralic soils. The charge distribution model parameters for phosphate-goethite adsorption were used to predict phosphate mobility on samples from 2 horizons of a ferralic soil containing large amounts of iron oxides. The soil reactivity was attributed to the iron oxides, and some specific parameters were determined by means of phosphate adsorption-desorption experiments and included in the model. Adsorption of phosphate in the upper horizon, which contained more organic carbon and phosphate than the deeper one, was modeled by using the information obtained for the soil and the charge distribution model parameters derived for phosphate-goethite interaction with no need of further optimization. In contrast, some extra fitting parameters were required to improve the modeling of the phosphate adsorption in the deeper horizon.

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Competitive adsorption of arsenate and phosphate onto calcite; experimental results and modeling with CCM and CD-MUSIC

Cited by 46 publications

References 49 publications

Complex mineral zoning patterns caused by ultra-local equilibrium at reaction interfaces

Complex mineral zoning patterns caused by ultra-local equilibrium at reaction interfaces

Calcite growth kinetics: Modeling the effect of solution stoichiometry

Modeling oxyanion adsorption on ferralic soil, part 1: Parameter validation with phosphate ion

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