Adsorption of antimony(V) on kaolinite as a function of pH, ionic strength and humic acid

School of Chemistry and Chemical Engineering, Shanxi Datong University, 037009 Datong, China
Environmental Earth Sciences (Impact Factor: 1.77). 04/2009; 60(4):715-722. DOI: 10.1007/s12665-009-0209-z


The present work investigated the adsorption and mobility (desorption) of Sb(V) on kaolinite using batch experiments. The
adsorption of Sb(V) on kaolinite was studied as a function of contact time, pH, ionic strength, humic acid (HA), initial Sb(V)
concentration and temperature. Kinetic studies suggest that the equilibrium is achieved within 24h. The adsorption of Sb(V)
was strongly affected by changes in I at low ionic strength and unaffected at high ionic strength. The adsorption is weakly
dependent on the presence of humic acid, but is strongly dependent on pH. Within the range tested, the optimal pH for Sb(V)
adsorption is 3.6, and close to 75% removal can be achieved. Desorption is dependent on the original suspension pH. The addition
sequence of Sb(V)/HA do not influence the adsorption of Sb(V) on kaolinite. The adsorption data fit both the Freundlich and
Langmuir isotherm. The thermodynamic parameters (ΔH
0, ΔS
0 and ΔG
0) were calculated from the temperature dependence, and the results suggest the endothermic and spontaneous nature of the process.


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Available from: Jianhong Xi, Apr 29, 2015
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    • "Kaolinite 1 (initial concentration) 6 25 12 [35] "
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    ABSTRACT: Schwertmannite was incorporated onto graphene oxide to form nanocomposites (GO–SCH) to serve as an adsorbent for Sb(V) removal. A synergistic effect on Sb(V) uptake was observed for the composite adsorbent. A maximum Sb(V) adsorption capacity of 158.6 mg Sb(V)/g of GO–SCH at an equilibrium Sb(V) concentration of 8.0 mg/L at pH 7.0 was obtained. This capacity is superior to either GO or SCH alone. The effect of contact time, solution pH and co-existing competitive anions on Sb(V) uptake by GO–SCH was evaluated. External mass transfer governed the Sb(V) uptake kinetics within 1 h. After 1 h, intraparticle diffusion gradually became predominant. Common co-existing anions at their natural environmental concentrations had little effect on the performance of GO–SCH. Sb(V) in spiked tap water (100 μg/L), simulated river water (6400 μg/L), and acid mine drainage (50,000 μg/L) was adsorbed by GO–SCH to well below the regulation levels for these waters. XRD and SEM analyses showed that SCH was well incorporated among GO platelets and highly dispersed on the GO carrier’s surface. FTIR and Raman spectra showed that both SCH and GO surfaces in the composites contribute to Sb(V) removal and SCH was the main active phase. This was also confirmed by XPS Fe 2p spectra. Sb 3d3/2 XPS spectra indicated that no surface precipitation or reduction of Sb(V) to Sb(III) occurred. Deconvolution of C 1s XPS spectra and Boehm titration indicated the surface carboxyl, lactonic and phenolic hydroxyl groups of GO also contribute to Sb(V) removal. The outstanding Sb(V) uptake ability of GO–SCH suggests it is a promising adsorbent for antimony removal from contaminated water.
    The Chemical Engineering Journal 06/2015; 270. DOI:10.1016/j.cej.2015.01.071 · 4.32 Impact Factor
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    • "Various functional groups such as hydroxyl, carbonyl and carboxyl groups are the putative active sites responsible for sorption capacity of chars towards ionic adsorbates (Corapcioglu and Huang, 1987). The Sb, being a metalloid, is sorbed mainly by chemisorption (Xi et al., 2010). Our model was developed on the basis of experimental results: (a) the predominant surface functional groups are amphoteric; and (b) Sb will adsorb preferentially in neutral/acidic pH (positive surface charge). "
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    ABSTRACT: Limited mechanistic knowledge is available on the interaction of biochar with trace elements (Sb and As) that exist predominantly as oxoanions. Soybean stover biochars were produced at 300 °C (SBC300) and 700 °C (SBC700), and characterized by BET, Boehm titration, FT-IR, NMR and Raman spectroscopy. Bound protons were quantified by potentiometric titration, and two acidic sites were used to model biochar by the surface complexation modeling based on Boehm titration and NMR observations. The zero point of charge was observed at pH 7.20 and 7.75 for SBC300 and SBC700, respectively. Neither antimonate (Sb(V)) nor antimonite (Sb(III)) showed ionic strength dependency (0.1, 0.01 and 0.001 M NaNO3), indicating inner sphere complexation. Greater adsorption of Sb(III) and Sb(V) was observed for SBC300 having higher –OH content than SBC700. Sb(III) removal (85%) was greater than Sb(V) removal (68%). Maximum adsorption density for Sb(III) was calculated as 1.88 × 10−6 mol m−2. The Triple Layer Model (TLM) successfully described surface complexation of Sb onto soybean stover-derived biochar at pH 4–9, and suggested the formation of monodentate mononuclear and binuclear complexes. Spectroscopic investigations by Raman, FT-IR and XPS further confirmed strong chemisorptive binding of Sb to biochar surfaces.
    Journal of Environmental Management 03/2015; 151. DOI:10.1016/j.jenvman.2014.11.005 · 2.72 Impact Factor
    • "Furthermore, in the pH 8 systems, Sb (V) adsorption is not detected in the 25°C and 35°C systems (consistent with adsorption edge results of Essington (2013)). These findings differ from those of Xi et al. (2010 and 2011). They observed the increased retention of Sb(V) by kaolinite and bentonite with increasing temperature in pH 6 systems. "

    Soil Science 02/2015; 180(2):54-66. DOI:10.1097/SS.0000000000000112 · 0.79 Impact Factor
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