Effects of γ-alumina nanoparticles on strontium sorption in smectite: Additive model approach

Mayordomo, Natalia; Alonso, Úrsula; Missana, Tiziana

doi:10.1016/j.apgeochem.2018.11.012

Cited by 17 publications

(14 citation statements)

References 64 publications

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“…They also showed that the metal-ion to ferrihydrite ratio determines the steepness of the adsorption edges in such scenarios. A similar approach was reported for γ-alumina [65], where the non-zero uptake of Sr covered a very broad pH range. From the available information, a definitive conclusion concerning the broad uptake curves as a function of pH, which can be considered as established according to Trivedi et al [64], cannot be drawn.…”

Section: Sr Adsorption Experiments On the Synthetic Iron(iii) Oxidesupporting

confidence: 52%

“…With respect to our uptake data, the zeta-potential results (Figure 3B) corroborate the batch experiment observations, because Sr causes a shift of the IEP at the low pH range, where adsorption is not decreasing towards zero (Figure 7). Pronounced uptake of Sr below the typical S-shape of the adsorption edge for cations (or very broad adsorption edges or distribution coefficient curves as a function of pH) were reported, for example, on ZrO 2 [61], hydrated TiO 2 [62], various other TiO 2 sorbents [63], hydrous Al, and Fe oxides [64] or γ-alumina [65]. While the pH range of the data on hematite by Karasyova et al [54] shown in Figure 7D does not allow a conclusion concerning this issue, Carrol et al report steeper pH-edges on goethite and amorphous silica [59].…”

Section: Sr Adsorption Experiments On the Synthetic Iron(iii) Oxidementioning

confidence: 99%

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Adsorption of Strontium onto Synthetic Iron(III) Oxide up to High Ionic Strength Systems

Garcia

Lützenkirchen

Huguenel³

et al. 2021

Minerals

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In this work, the adsorption behavior of Sr onto a synthetic iron(III) oxide (hematite with traces of goethite) has been studied. This solid, which might be considered a representative of Fe3+ solid phases (iron corrosion products), was characterized by X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS), and its specific surface area was determined. Both XRD and XPS data are consistent with a mixed solid containing more than 90% hematite and 10% goethite. The solid was further characterized by fast acid-base titrations at different NaCl concentrations (from 0.1 to 5 M). Subsequently, for each background NaCl concentration used for the acid-base titrations, Sr-uptake experiments were carried out involving two different levels of Sr concentration (1·10−5 and 5·10−5 M, respectively) at constant solid concentration (7.3 g/L) as a function of −log([H+]/M). A Surface Complexation Model (SCM) was fitted to the experimental data, following a coupled Pitzer/surface complexation approach. The Pitzer model was applied to aqueous species. A Basic Stern Model was used for interfacial electrostatics of the system, which includes ion-specific effects via ion-specific pair-formation constants, whereas the Pitzer-approach involves ion-interaction parameters that enter the model through activity coefficients for aqueous species. A simple 1-pK model was applied (generic surface species, denoted as >XOH−1/2). Parameter fitting was carried out using the general parameter estimation software UCODE, coupled to a modified version of FITEQL2. The combined approach describes the full set of data reasonably well and involves two Sr-surface complexes, one of them including chloride. Monodentate and bidentate models were tested and were found to perform equally well. The SCM is particularly able to account for the incomplete uptake of Sr at higher salt levels, supporting the idea that adsorption models conventionally used in salt concentrations below 1 M are applicable to high salt concentrations if the correct activity corrections for the aqueous species are applied. This generates a self-consistent model framework involving a practical approach for semi-mechanistic SCMs. The model framework of coupling conventional electrostatic double layer models for the surface with a Pitzer approach for the bulk solution earlier tested with strongly adsorbing solutes is here shown to be successful for more weakly adsorbing solutes.

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Section: Sr Adsorption Experiments On the Synthetic Iron(iii) Oxidesupporting

confidence: 52%

Section: Sr Adsorption Experiments On the Synthetic Iron(iii) Oxidementioning

confidence: 99%

Adsorption of Strontium onto Synthetic Iron(III) Oxide up to High Ionic Strength Systems

Garcia

Lützenkirchen

Huguenel³

et al. 2021

Minerals

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“…The predominant adsorption mechanism in the FEBEX-clay for alkaline cations (Cs + , Ca 2+ , Sr 2+ ) [ 23 , 40 , 45 , 46 , 47 , 47 ] is cation exchange (Equation (2)), and for these elements, the adsorption is highly dependent on the ionic strength of the solution, but almost independent of the pH up to pH 9 or even higher.…”

Section: Discussionmentioning

confidence: 99%

Analysis of Cadmium Retention Mechanisms by a Smectite Clay in the Presence of Carbonates

Missana¹,

Alonso²,

Mayordomo

et al. 2023

Toxics

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Cadmium (Cd) is a toxic heavy metal with very low permissible exposure limits and is, thus, a very dangerous pollutant for the environment and public health and is considered by the World Health Organisation as one of the ten chemicals of major public concern. Adsorption onto solid phases and (co)precipitation processes are the most powerful mechanisms to retain pollutants and limit their migration; thus, the understanding of these processes is fundamental for assessing the risks of their presence in the environment. In this study, the immobilisation of Cd by smectite clay has been investigated by batch sorption tests, and the experimental data were interpreted with a thermodynamic model, including cation exchange and surface complexation processes. The model can describe the adsorption of Cd in smectite under a wide range of experimental conditions (pH, ionic strength, and Cd concentration). Under the conditions analysed in this study, the precipitation of otavite (CdCO3) is shown to have a limited contribution to Cd immobilisation.

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“…This work aims to analyze Cd immobilization in γ-Al 2 O 3 nanoparticles and in mixtures of FEBEX smectite and γ-Al 2 O 3 nanoparticles with a combined experimental and theoretical approach. Both sorbents were selected because of their ubiquity and their good cation sorption capabilities (γ-Al 2 O 3 nanoparticles [34,35] and FEBEX smectite [14,[36][37][38][39]). Cd sorption on γ-Al 2 O 3 nanoparticles, and in mixtures of smectite and γ-Al 2 O 3 nanoparticles was studied in a wide range of pH values (3.0-11.0), Cd concentrations (from 1•10 −10 to 1•10 −3 M), Cl − concentrations (0, 1•10 −8 , and 1•10 −3 M), ionic strengths (from 5•10 −4 to 1•10 −1 M), and mixture composition (from 0% γ-Al 2 O 3 nanoparticles to 100% γ-Al 2 O 3 nanoparticles).…”

Section: Introductionmentioning

confidence: 99%

Cadmium Sorption on Alumina Nanoparticles and Mixtures of Alumina and Smectite: An Experimental and Modelling Study

Mayordomo,

Missana,

Alonso

2023

Minerals

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Cadmium (Cd) is one of the most toxic transition metals for living organisms. Thus, effective measures to remediate Cd from water and soils need to be developed. Cd immobilization by alumina and mixtures of alumina and smectite have been analyzed experimentally and theoretically by sorption experiments and sorption modelling, respectively. Removal of aqueous Cd was dependent on pH and Cd concentration, being maximal for pH > 7.5. A two-site non-electrostatic sorption model for Cd sorption on alumina was developed and it successfully reproduced the experimental Cd immobilization on alumina. Cd sorption on mixtures of alumina and smectite were depending on pH, ionic strength, and alumina content in the mixture. Cd removal in mixtures increased with alumina content at high pH and ionic strength values. However, Cd sorption decreased with increasing alumina content under acidic conditions and low ionic strength. This effect was the result of alumina dissolution and the release of Al3+ into the suspension at low pH values. Modelling of Cd sorption on mixtures of alumina and smectite was performed by considering the individual Cd sorption models for alumina and smectite. It could be shown that the contributions of the individual sorption models were additive in the model for the mixtures when the competition of Al3+ with Cd2+ for cation exchange sites in smectite was included.

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Effects of γ-alumina nanoparticles on strontium sorption in smectite: Additive model approach

Cited by 17 publications

References 64 publications

Adsorption of Strontium onto Synthetic Iron(III) Oxide up to High Ionic Strength Systems

Adsorption of Strontium onto Synthetic Iron(III) Oxide up to High Ionic Strength Systems

Analysis of Cadmium Retention Mechanisms by a Smectite Clay in the Presence of Carbonates

Cadmium Sorption on Alumina Nanoparticles and Mixtures of Alumina and Smectite: An Experimental and Modelling Study

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