Antimony (V) Adsorption at the Hematite–Water Interface: A Macroscopic and In Situ ATR-FTIR Study

The environmental mobility of antimony (Sb) is largely unexplored in geochemical environments. Iron oxide minerals are considered major sinks for Sb. Among the different oxidation states of Sb, (+) V is found more commonly in a wide redox range. Despite many adsorption studies of Sb (V) with various iron oxide minerals, detailed research on the adsorption mechanism of Sb (V) on hematite using macroscopic, spectroscopic, and surface complexation modeling is rare. Thus, the main objective of our study is to evaluate the surface complexation mechanism of Sb (V) on hematite under a range of solution properties using macroscopic, in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopic, and surface complexation modeling. The results indicate that the Sb (V) adsorption on hematite was highest at pH 4–6. After pH 6, the adsorption decreased sharply and became negligible above pH 9. The effect of ionic strength was negligible from pH 4 to 6. The spectroscopic results confirmed the presence of inner- and outer-sphere surface complexes at lower pH values, and only outer-sphere-type surface complex at pH 8. Surface complexation models successfully predicted the Sb (V) adsorption envelope. Our research will improve the understanding of Sb (V) mobility in iron-oxide-rich environments.

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In situ ATR–FTIR and surface complexation modeling studies on the adsorption of dimethylarsinic acid and p-arsanilic acid on iron-(oxyhydr)oxides

Journal of Colloid and Interface Science ◽

10.1016/j.jcis.2011.02.040 ◽

2011 ◽

Vol 358 (2) ◽

pp. 534-540 ◽

Cited By ~ 37

Author(s):

William Mitchell ◽

Sabine Goldberg ◽

Hind A. Al-Abadleh

Keyword(s):

Surface Complexation ◽

Dimethylarsinic Acid ◽

Surface Complexation Modeling ◽

Arsanilic Acid ◽

Modeling Studies

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Benzenecarboxylate Surface Complexation at the Goethite (α-FeOOH)/Water Interface: I. A Mechanistic Description of Pyromellitate Surface Complexes from the Combined Evidence of Infrared Spectroscopy, Potentiometry, Adsorption Data, and Surface Complexation Modeling

Langmuir ◽

10.1021/la991407o ◽

2000 ◽

Vol 16 (13) ◽

pp. 5719-5729 ◽

Cited By ~ 48

Author(s):

Jean-François Boily ◽

Nils Nilsson ◽

Per Persson ◽

Staffan Sjöberg

Keyword(s):

Infrared Spectroscopy ◽

Surface Complexation ◽

Water Interface ◽

Surface Complexation Modeling ◽

Surface Complexes ◽

Adsorption Data

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THERMODINAMIC PARAMETERS ON THE SORPTION OF PHOSPHATE IONS BY MONTMORILLONITE

Jurnal Sains Dasar ◽

10.21831/jsd.v4i1.8429 ◽

2016 ◽

Vol 4 (1) ◽

Author(s):

Ikhsan Jaslin ◽

Wijayanti Endang ◽

Sunarto Sunarto

Keyword(s):

Active Sites ◽

Surface Complexation ◽

Outer Sphere ◽

Hydroxyl Groups ◽

Process Data ◽

Surface Complexes ◽

Surface Complexation Model ◽

Surface Hydroxyl ◽

Phosphate Ions ◽

Sorbate Concentration

The sorption of phosphate by montmorillonite at 10, 30, and 50 oC were investigated aiming to mainly determine thermodynamic parameters for the formation of surface complexes in the adsorption of phosphate ions by montmorillonite. Data were collected by adsorption edge experiments investigating the effect of pH, adsorption isotherms enabling the effect of sorbate concentration, and acid-base titration calculating protons released or taken up by adsorption process. Data analysis was carried out using surface complexation model to fit the data collected in this study using the parameters obtained from previous study, as well as to calculate the values of ΔH and ΔS. Previous study reported that phosphate ions formed two outer-sphere surface complexes with active sites of montmorillonite through hydrogen bonding. In the first complex, [(XH)0– H2L─]─, the phosphate was held to permanent-charge X─ sites on the tetrahedral siloxane faces, and the second complex, [[(SO─)(SOH)]– – [H2L]─] 2─ was formed through the interaction between the phosphate and variable charge surface hydroxyl groups at the edges of montmorillonite crystals and on the octahedral alumina faces. The values of ΔH for the first and second reactions are 39.756 and 3.765x10-7 kJ mol‒1 respectively. Since both reactions have positive enthalpy values, it can be concluded that the reactions are endothermic. Large energy for the first reaction is needed by X─ sites (permanent negatively charge sites of montmorillonite) to be partially desolvated, on which K+ or other surface cations are replaced by H+ ions in the surface protonated process, and are then ready to interact phosphate ions in the solution. Small values of ΔH for the second reactions indicates that hydrogen bonds formed by phosphate and SOH sites in the second reaction are easily broken out, and the phosphate can easily desorbed from the surface. The values of ΔS for the first and second reactions are 122.523 and 2.393 x10-2 J K‒1 mol‒1, which are greater than -10 kJ mol‒1 and indicates that the surface reactions occurs through dissociative mechanisms.Keywords: montmorillonite, adsorption edge, extended constant capacitance, surface complexation model, enthalpy, reaction mechanisms

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Cadmium adsorption capacity of selected Ontario soils

Canadian Journal of Soil Science ◽

10.4141/cjss96-025 ◽

1996 ◽

Vol 76 (2) ◽

pp. 183-189 ◽

Cited By ~ 34

Author(s):

K. A. Bolton ◽

L. J. Evans

Keyword(s):

Soil Properties ◽

Linear Regression Analysis ◽

Surface Complexation ◽

Solution Concentration ◽

Multiple Linear Regression Analysis ◽

Batch Adsorption ◽

Surface Complexation Modeling ◽

Ph Values ◽

Cadmium Adsorption ◽

Cd Adsorption

The retention of Cd by selected Ontario soils with a range of soil properties was investigated. Batch adsorption experiments were carried out at the actual (unadjusted) PH of the soil and at a range of PH values adjusted by the addition of acid or base. For all soils, Cd adsorption increased with increasing pH and with increasing Cd solution concentration. The adsorption data was fitted, by a linear least squares technique, to the Langmuir adsorption isotherm. Maximum adsorption, qmax, at unadjusted soil pH values ranged from less than 8 mmol kg−1 for the Fox sandy soil to 64.8 mmol kg−1 for the Hanbury heavy clay soil. Calculated Cd adsorption maxima were regressed against measured soil properties to determine the most important properties involved in the adsorption of Cd. Multiple linear regression analysis revealed the best model to be qmax = 8.33 + 0.67 (organic carbon) + 4.37 (inorganic – poorly crystalline Fe, Fepc). Surface complexation modeling indicates that humic surfaces account for adsorption at pH values beginning at approximately 3.5 and that hydrous ferric oxide surfaces account for Cd adsorption at pH values greater than 7. Key words: Cadmium adsorption, Langmuir isotherm, surface complexation, soil contamination

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Competitive Adsorption of As(III), As(V), and PO4 by an Iron Oxide Impregnated Activated Carbon: Surface Complex Modeling

Water Air & Soil Pollution ◽

10.1007/s11270-020-04853-y ◽

2020 ◽

Vol 231 (9) ◽

Author(s):

T. Angele Ngantcha-Kwimi ◽

Brian E. Reed

Keyword(s):

Iron Oxide ◽

Competitive Adsorption ◽

Surface Complexation ◽

Carbon Surface ◽

Hydrous Ferric Oxide ◽

Layer Model ◽

Surface Complexation Modeling ◽

Adsorption Data ◽

Double Layer Model ◽

Binuclear Species

Abstract The objective of this study was to predict the competitive adsorption of As(III), As(V), and PO4 by an iron oxide impregnated carbon (L-Act, 9% Fe(III) amorphous iron oxide) over a range of environmental conditions using the surface complexation modeling (SCM) approach. L-Act surface complexation constants determined from a single pH-adsorption edge were used to predict pH-dependent competitive removal in singular, binary, and tertiary adsorbate systems. As(III), As(V), and PO4 complexes were modeled as bidentate binuclear species at low pH and monodentate species at high pH using the two monoprotic surface site/diffuse electric double layer model (2MDLM). F values determined based on 2MDLM predictions were close to those calculated by FITEQL (a statistical optimization program) demonstrating the effectiveness of the 2MDLM in describing adsorption behavior. F values were generally in the recommended range of 0.1–20 indicating a good fit between the data and the model. The 2MDLM also successfully predicted As(III)/As(V)/PO4 adsorption data of hydrous ferric oxide and goethite adsorbents from the literature.

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Retracted Article: Enhanced adsorption of Eu(iii) on mesoporous Al2O3/expanded graphite composites investigated by macroscopic and microscopic techniques

Dalton Transactions ◽

10.1039/c2dt31510f ◽

2012 ◽

Vol 41 (43) ◽

pp. 13388-13394 ◽

Cited By ~ 81

Author(s):

Yubing Sun ◽

Changlun Chen ◽

Xiaoli Tan ◽

Dadong Shao ◽

Jiaxing Li ◽

...

Keyword(s):

Adsorption Mechanism ◽

Surface Complexation ◽

Expanded Graphite ◽

Outer Sphere ◽

Sphere Surface ◽

Inner Sphere ◽

Retracted Article ◽

Enhanced Adsorption ◽

Graphite Composites ◽

Microscopic Techniques

The adsorption mechanism between Eu(iii) and mesoporous Al2O3/EG composites shifts from outer-sphere to inner-sphere surface complexation with increasing pH.

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