Sorption of selenium oxyanions on TiO2 (rutile) studied by batch or column experiments and spectroscopic methods

Švecová, Lenka; Dossot, Manuel; Cremel, Sébastien; Simonnot, Marie-Odile; Sardin, M.; Humbert, Bernard; Auwer, Christophe Den; Michot, Laurent J.

doi:10.1016/j.jhazmat.2011.02.090

Cited by 26 publications

(6 citation statements)

References 53 publications

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“…In addition, oxo-anions have also demonstrated trends in sorption strength. Oxo-anions that have a strong affinity for the metal (hydr)oxide surface (e.g., HSeO 3 – H 2 PO 4 – , H 2 AsO 4 – ), have been shown to form stable inner-sphere complexes regardless of metal (hydr)oxide composition. ,− These high-affinity oxo-anions have high intrinsic equilibrium constants and can disrupt the water coordination sphere of the metal (hydr)oxide to directly coordinate or chemisorb to the surface. In general these strongly coordinated surface species are relatively immobile and much less likely to desorb from the sorbent surface as solution conditions change .…”

Section: Selectivity Due To Differences In Surface Complexationmentioning

confidence: 99%

Exploring the Mechanisms of Selectivity for Environmentally Significant Oxo-Anion Removal during Water Treatment: A Review of Common Competing Oxo-Anions and Tools for Quantifying Selective Adsorption

Pincus

Rudel

Petrović

et al. 2020

Environ. Sci. Technol.

141

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Development of novel adsorbents often neglects the competitive adsorption between co-occurring oxo-anions, overestimating realistic pollutant removal potentials, and overlooking the need to improve selectivity of materials. This critical review focuses on adsorptive competition between commonly co-occurring oxo-anions in water and mechanistic approaches for the design and development of selective adsorbents. Six “target” oxo-anion pollutants (arsenate, arsenite, selenate, selenite, chromate, and perchlorate) were selected for study. Five “competing” co-occurring oxo-anions (phosphate, sulfate, bicarbonate, silicate, and nitrate) were selected due to their potential to compete with target oxo-anions for sorption sites resulting in decreased removal of the target oxo-anions. First, a comprehensive review of competition between target and competitor oxo-anions to sorb on commonly used, nonselective, metal (hydr)oxide materials is presented, and the strength of competition between each target and competitive oxo-anion pair is classified. This is followed by a critical discussion of the different equations and models used to quantify selectivity. Next, four mechanisms that have been successfully utilized in the development of selective adsorbents are reviewed: variation in surface complexation, Lewis acid/base hardness, steric hindrance, and electrostatic interactions. For each mechanism, the oxo-anions, both target and competitors, are ranked in terms of adsorptive attraction and technologies that exploit this mechanism are reviewed. Third, given the significant effort to evaluate these systems empirically, the potential to use computational quantum techniques, such as density functional theory (DFT), for modeling and prediction is explored. Finally, areas within the field of selective adsorption requiring further research are detailed with guidance on priorities for screening and defining selective adsorbents.

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Section: Selectivity Due To Differences In Surface Complexationmentioning

confidence: 99%

Exploring the Mechanisms of Selectivity for Environmentally Significant Oxo-Anion Removal during Water Treatment: A Review of Common Competing Oxo-Anions and Tools for Quantifying Selective Adsorption

Pincus

Rudel

Petrović

et al. 2020

Environ. Sci. Technol.

141

View full text Add to dashboard Cite

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“…For this reason, one of the most effective sorbents for selenium oxoanions are layered double hydroxides (LDHs) which, due to the higher PZC in the range of ∼8–12.5, can display better selenium removal capacities at pH > 7 compared to other common metal oxide sorbents such as TiO 2 , − Al 2 O 3 , , and iron oxides. , LDHs are anionic clays that have been investigated for a wide number of uses, including as photo- and electrocatalysts, , gas adsorption materials, , catalyst supports, flame retardants, and for water treatment , and biomedical/drug-delivery applications. , LDHs contain positively charged layers of brucite-like octahedral hydroxide sheets separated by compensating anions and water molecules that can be exchanged with other anions , and can adopt the formula [M 1– x II M x III (OH) 2 ] x + [A x / n n – ] x − · m H 2 O, where M II is a divalent metal, M III is a trivalent metal, A n – is an exchangeable anion with a valence of n , and the x value is in the range of 0–0.33 …”

Section: Introductionmentioning

confidence: 99%

Layered Double Hydroxide/Chitosan Nanocomposite Beads as Sorbents for Selenium Oxoanions

Dopilka

Kraetz

et al. 2018

Ind. Eng. Chem. Res.

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Layered double hydroxide (LDH) nanoparticles are effective sorbents for selenium oxoanions but must be fabricated in a suitable fashion for implementation in water treatment applications using packed columns. In this work, we demonstrate the preparation of nanocomposite beads prepared from Mg–Al–CO3 LDH nanoparticles and chitosan, a sustainable and biodegradable biopolymer. The synthesis of the nanocomposite beads is achieved by direct mixing or in situ synthesis of the LDH nanoparticles into the chitosan matrix. The effect of the preparation route on the nanocomposite structure, maximum loading of LDH in the composite, removal kinetics, and the maximum sorption capabilities for selenate and selenite oxoanions are studied and compared to LDH nanopowders and granular media. The results indicate that the in situ synthesis of LDH inside the beads leads to several favorable characteristics such as a higher mass loading of LDH and better dispersion of the nanoparticles while displaying good selenium removal over a wide pH range, superior sorption capacities to the nanopowder, and sorption kinetics similar to those of the granulated media. The maximum adsorption capacities for the nanocomposite beads from Langmuir isotherms were 17 mg/g for Se(IV) and ∼12 mg/g for Se(VI) with respect to the mass of LDH, which is higher than reported capacities obtained in chitosan beads embedded with other nanocrystalline metal oxide fillers. These results show that the LDH/chitosan nanocomposite beads are promising alternatives to granulated media for selenium removal and sheds light on how best to design and fabricate high performance and sustainable nanoenabled sorbents for water treatment applications.

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“…Among these, sorption is considered as an efficient, simple, and low-cost process, particularly suitable for removing contaminated selenium at low levels and point-of-use applications . Inorganic titanium oxide, − aluminum oxide, − iron oxides, − mixed metal oxides, − and other minerals − were commonly used for this application. However, due to the limited activated sites for sorption, most of the inorganic oxide sorbents exhibit low capacity for capturing selenium.…”

Section: Introductionmentioning

confidence: 99%

Selenium Sequestration in a Cationic Layered Rare Earth Hydroxide: A Combined Batch Experiments and EXAFS Investigation

Zhu

Zhang

et al. 2017

Environ. Sci. Technol.

105

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Selenium is of great concern owing to its acutely toxic characteristic at elevated dosage and the long-term radiotoxicity of Se. The contents of selenium in industrial wastewater, agricultural runoff, and drinking water have to be constrained to a value of 50 μg/L as the maximum concentration limit. We reported here the selenium uptake using a structurally well-defined cationic layered rare earth hydroxide, Y(OH)Cl·1.5HO. The sorption kinetics, isotherms, selectivity, and desorption of selenite and selenate on Y(OH)Cl·1.5HO at pH 7 and 8.5 were systematically investigated using a batch method. The maximum sorption capacities of selenite and selenate are 207 and 124 mg/g, respectively, both representing the new records among those of inorganic sorbents. In the low concentration region, Y(OH)Cl·1.5HO is able to almost completely remove selenium from aqueous solution even in the presence of competitive anions such as NO, Cl, CO, SO, and HPO. The resulting concentration of selenium is below 10 μg/L, well meeting the strictest criterion for the drinking water. The selenate on loaded samples could be desorbed by rinsing with concentrated noncomplexing NaCl solutions whereas complexing ligands have to be employed to elute selenite for the material regeneration. After desorption, Y(OH)Cl·1.5HO could be reused to remove selenate and selenite. In addition, the sorption mechanism was unraveled by the combination of EDS, FT-IR, Raman, PXRD, and EXAFS techniques. Specifically, the selenate ions were exchanged with chloride ions in the interlayer space, forming outer-sphere complexes. In comparison, besides anion exchange mechanism, the selenite ions were directly bound to the Y center in the positively charged layer of [Y(OH)(HO)] through strong bidentate binuclear inner-sphere complexation, consistent with the observation of the higher uptake of selenite over selenate. The results presented in this work confirm that the cationic layered rare earth hydroxide is an emerging and promising material for efficient removal of selenite and selenate as well as other anionic environmental pollutants.

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Sorption of selenium oxyanions on TiO2 (rutile) studied by batch or column experiments and spectroscopic methods

Cited by 26 publications

References 53 publications

Exploring the Mechanisms of Selectivity for Environmentally Significant Oxo-Anion Removal during Water Treatment: A Review of Common Competing Oxo-Anions and Tools for Quantifying Selective Adsorption

Exploring the Mechanisms of Selectivity for Environmentally Significant Oxo-Anion Removal during Water Treatment: A Review of Common Competing Oxo-Anions and Tools for Quantifying Selective Adsorption

Layered Double Hydroxide/Chitosan Nanocomposite Beads as Sorbents for Selenium Oxoanions

Selenium Sequestration in a Cationic Layered Rare Earth Hydroxide: A Combined Batch Experiments and EXAFS Investigation

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