A predictive model (ETLM) for As(III) adsorption and surface speciation on oxides consistent with spectroscopic data

Sverjensky, Dimitri A.; Fukushi, Keisuke

doi:10.1016/j.gca.2006.05.012

Cited by 105 publications

(103 citation statements)

References 64 publications

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“…4a, b). Although previous studies showed that As(V) always had stronger affinity than As(III) to adsorb on Fe oxides (Tufano et al 2008;Sverjensky and Fukushi 2006), our results suggested that the released As(V) could not be further adsorbed on hematite (Fig. 4a).…”

Section: Oxidation Of As(iii) In Mn(ii)-hematite Suspensioncontrasting

confidence: 79%

Abiotic oxidation of Mn(II) and its effect on the oxidation of As(III) in the presence of nano-hematite

Han

2012

Ecotoxicology

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Manganese (hydr)oxides (MnO(x)) is a powerful oxidant in the oxidation of As(III) in natural environment. Under some circumstances, Mn(II) can be oxidized to MnO(x) which in turn accelerates the oxidation of As(III). However, to the best of our knowledge, little is known regarding how Mn(II) affects the oxidation of both the dissolved and the adsorbed As(III) in aquatic environments. In this study, effects of abiotic oxidation of Mn(II) on the oxidation of As(III) were investigated. Kinetic results as well as TEM and XRD analyses confirmed the formation of amorphous MnO(x) after sorption of Mn(II) on hematite nano-particles under oxic conditions. Mn(II) was oxidized to Mn(III) and then to Mn(IV), and this process was dependent upon pH and Mn(II) concentrations. The newly formed MnO(x) played an important role in the further oxidation of the dissolved and the adsorbed As(III) on hematite, and the oxidation rate of As(III) increased with the rising Mn(II) concentrations. As the adsorbed As(III) was oxidized to As(V), a fraction of As(V) was released into the solution, which increased the mobility of As. The present study reveals that abiotic oxidation of Mn(II) affects the oxidation of As(III) in aquatic environment.

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Section: Oxidation Of As(iii) In Mn(ii)-hematite Suspensioncontrasting

confidence: 79%

Abiotic oxidation of Mn(II) and its effect on the oxidation of As(III) in the presence of nano-hematite

Han

2012

Ecotoxicology

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“…5). The monodentate binding is different from the bidentate binding common to Fe and Al oxides [26]. One zirconyl cation can thereby accommodate up to two arsenate anions at hydroxyl edges, which readily explains its high As sorption capacity [6].…”

Section: Discussionmentioning

confidence: 98%

Adsorption mechanism of arsenate by zirconyl-functionalized activated carbon

Schmidt

Власова

Zuzaan

et al. 2008

Journal of Colloid and Interface Science

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Arsenate [As(V)] and arsenite [As(III)] sorption at the solid-water interface of activated carbon impregnated with zirconyl nitrate (Zr-AC) was investigated using X-ray absorption spectroscopy (XAS) and surface complexation modeling. The XAS data at the Zr K-edge suggest that the structure of the zirconyl nitrate coating is built from chains of edge-sharing ZrO 8 trigonal dodecahedra bound to each other through two double hydroxyl bridges. The 8-fold coordination of each Zr atom is completed by four O atoms, which share a bit less than the two theoretically possible bidentate nitrate groups. On impregnation, two of the O atoms may lose their nitrate group and be transformed to hydroxyl groups ready for binding to carboxylic or phenolic ligands at the AC surface. As K-edge XANES results showed the presence of only As(V) on adsorption regardless of the initial As oxidation state. Oxidation to As(V) is probably mediated by available carbon species on the AC surface as found by batch titration. Zr K-edge EXAFS data indicate that arsenate tetrahedra form monodentate mononuclear surface complexes with free hydroxyl groups of zirconyl dodecahedra, whereby each bidentate nitrate group is exchanged by up to two arsenate groups. The inner-sphere arsenate binding to the Zr-AC surface sites constrained with the spectroscopic results was used in the formulation of a surface complexation model to successfully describe the adsorption behavior of arsenate in the pH range between 4 and 12. The results suggest therefore that Zr-AC is an effective adsorbent for arsenic removal due to its high surface area and the presence of high affinity surface hydroxyl groups.

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“…The sample characteristics and surface protonation and electrolyte adsorption equilibrium constants used in the present study are summarized in Table 1. Although HFO and ferrihydrite might be thought to have extremely similar surface chemical properties, we distinguished between them in our previous study of As(III) adsorption (Sverjensky and Fukushi, 2006b). By using differences in the pH ZPC (i.e.…”

Section: Aqueous Speciation Surface Protonation and Electrolyte Adsomentioning

confidence: 99%

“…(6)-(9) using the tabulated values of N S , A S , pH ZPC and DpK h n . a Values generated by regression of arsenate adsorption as a function of surface coverage, with the following exceptions: values for HFO, ferrihydrite, b-Al(OH) 3 , FeOOH (Dixit and Hering, 2003) and amAEAlO were taken from previous regression calculations of arsenite adsorption data on the same samples (Sverjensky and Fukushi, 2006b); the value for the Manning and Goldberg goethite was generated with the equation for the line in Fig. 6 based on arsenite and sulfate regressions (Fukushi and Sverjensky, 2006).…”

Section: Aqueous Speciation Surface Protonation and Electrolyte Adsomentioning

confidence: 99%

A predictive model (ETLM) for arsenate adsorption and surface speciation on oxides consistent with spectroscopic and theoretical molecular evidence

Fukushi

Sverjensky

2007

Geochimica et Cosmochimica Acta

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A predictive model (ETLM) for As(III) adsorption and surface speciation on oxides consistent with spectroscopic data

Cited by 105 publications

References 64 publications

Abiotic oxidation of Mn(II) and its effect on the oxidation of As(III) in the presence of nano-hematite

Abiotic oxidation of Mn(II) and its effect on the oxidation of As(III) in the presence of nano-hematite

Adsorption mechanism of arsenate by zirconyl-functionalized activated carbon

A predictive model (ETLM) for arsenate adsorption and surface speciation on oxides consistent with spectroscopic and theoretical molecular evidence

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