The Role of Surface Heterogeneity in Adsorption

Halsey, G. D.

doi:10.1016/s0360-0564(08)60616-1

Cited by 166 publications

(57 citation statements)

References 10 publications

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“…Halsey (1952) and Adamson (1976) Tables 8 and 9. The D value data were generated by assuming an initial U concentration, determining the (x/m) value with the Freundlich-like constants given in Table 9 and using the (x/m) value to compute a C value with the Freundlich constants given in Table 8.…”

Section: Discussionmentioning

confidence: 99%

Sorption of Trace Constituents from Aqueous Solutions Onto Secondary Minerals. I. Uranium

Ames

1983

Clays and clay miner.

106

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Abstract--Well-characterized American Petroleum Institute clay standards, source clays from The Clay Minerals Society, and other secondary minerals were used to determine the effects of U concentration, temperature, and solution composition on U-sorption properties. Uranium concentrations ranged from about 1.00 x 10 -4 M to 4.00 x 10 7 M, temperatures from 5 ~ to 65~ and solution compositions containing 0.01 M NaCl and 0.01 M NaHCO3. Silica gel efficiently sorbed uranyl carbonate anion complexes. The higher cation-exchange capacity materials most readily sorbed uranyl ions from the 0.01 M NaCl solution. Temperature increases tended to affect uranyl ion sorption adversely except when the U was present as carbonate complexes. Noncrystalline ferric oxyhydroxides sorbed uranyl ions much more efficiently than any of the secondary crystalline minerals studied. A method for accurately extrapolating U-sorption efficiencies between experimental points based on the Freundlich equation is presented.

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Section: Discussionmentioning

confidence: 99%

Sorption of Trace Constituents from Aqueous Solutions Onto Secondary Minerals. I. Uranium

Ames

1983

Clays and clay miner.

106

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“…The natural clinoptilolite (NCp) zeolite employed in our research was obtained from the region of the West Semnan, Central Alborz Mountains, Iran and its structural properties is as (Na, K, Ca) 6 (Si, Al) 36 …”

Section: Experimental Materials and Reagentsmentioning

confidence: 99%

“…The Hasley isotherm model can be utilized to evaluate the multilayer adsorption for the adsorption of 90 Sr at a relatively large distance from the surface. Herein we discuss this isotherm model with equilibrium equation below (9) [36]:…”

Section: Adsorption Reaction Isothermsmentioning

confidence: 99%

Effective removal of radioactive 90Sr by CuO NPs/Ag-clinoptilolite zeolite composite adsorbent from water sample: isotherm, kinetic and thermodynamic reactions study

et al. 2016

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In this research, the natural zeolite named clinoptilolite (NCp) was considered as an applicable base structure for subsequent preparation and modification by pre-selected chemical agents to use for removal/adsorption goals in progress. To make Na-clinoptilolite form, the mentioned zeolite undergoes variations by treating with NaCl salt. Ion exchange procedure was utilized to imprint silver ions (Ag ? ) from silver (I) nitrate solution as silver precursor on the modified clinoptilolite zeolite structure to attain Ag-clinoptilolite zeolite. Tenorite (CuO) NPs have been then dispersed and deposited on the external surface of the pre-prepared Ag-clinoptilolite zeolite through impregnation method to prepare the CuO NPs/Ag-clinoptilolite zeolite as a novel composite adsorbent. A series of analyses techniques including SEM-EDAX, XRD and FT-IR were applied for characterization and identification of crystal structure, morphology and elemental composition of the synthesized samples. The removal and adsorption process of radioactive strontium-90 ( 90 Sr) by CuO NPs/Agclinoptilolite zeolite composite adsorbent was exploited under various experimental conditions including pH, amount of adsorbent and the contact time at room temperature and the final optimized procedure used for removal of probable presence of 90 Sr in water sample of Bushehr city. Adsorption isotherm models including Langmuir, Freundlich, Temkin, D-R, H-J and Hasley have been applied and equilibrium adsorption data was better fitted to the Freundlich, Temkin, H-J and Halsey isotherms. The reaction kinetic information was studied by utilizing pseudo first and second orders, Elovich and Intra particle diffusion kinetic models. The adsorption kinetics is finely described by the pseudo second-order model. The energy of activation E a calculated using the Arrhenius equation was found to be 44.75 kJ/mol. Further, the evaluation of the thermodynamic parameters such as DG 0 , DH 0 and DS 0 , denoted that adsorption process of 90 Sr was spontaneous and illustrates a chemical adsorption properties and exothermic nature of the adsorption. The obtained results revealed that 90 Sr ions were removed by CuO NPs/Agclinoptilolite zeolite composite under optimized conditions after 6 h with a yield more than 97 %.

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“…It was found that Freundlich isotherm held for the heterogenous surface when adsorption energy was reciprocal to logΘ, where Θ was a/a m (a degree of surface coverage). 28 …”

Section: Freundlich Isothermmentioning

confidence: 99%

Study of silver adsorption on montmorillonite

Praus¹,

Turicová²,

Valášková³

2008

J. Braz. Chem. Soc.

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Neste trabalho foi estudada a adsorção de Ag + sobre montmorilonita (MMT) do tipo Wyoming rica em Na + . Os dados de adsorção foram ajustados de acordo com várias isotermas comuns, mas os melhores parâmetros de regressão foram obtidos pelo modelo de Langmuir, indicando que Ag + foi adsorvido na superfície de MMT formando monocamadas. A adsorção de pequenas quantidades de Ag + promoveu o aumento da área superficial específica (SSA) de micro (r = 0.4-0.5 nm) a mesoporos (r = 1.5-3 nm). A intercalação de Ag + em MMT foi observada por difração de raios-X (XRD). Com o aumento da concentração de soluções de nitrato de prata, a quantidade de Ag + em MMT também aumentou e a estrutura em camadas gradualmente sofreu colapso e esfoliação. As amostras de MTT saturadas com Ag + foram tratadas com solução de boro hidreto de sódio para produzir Ag 0 . Foi estimado um tamanho médio de L 111 = 8.5(1) nm dos cristalitos de Ag 0 . As nanopartículas de prata metálica ficaram localizadas na superfície e nas bordas dos cristais de MMT.In this study Ag + adsorption on Na + -rich montmorillonite (MMT) type Wyoming was studied. Adsorption data were fitted with several common isotherms but the best regression parameters were obtained for Langmuir model. It indicates that Ag + was adsorbed on the MMT surface forming a monolayer. By adsorption of small amounts of Ag + enlargement of the specific surface area (SSA) of micro-(r = 0.4-0.5 nm) and mesopores (r = 1.5-3 nm) was found. Intercalation of Ag + into MMT was observed using X-ray diffraction (XRD). With increasing concentration of the silver nitrate solutions the content of Ag + in MMT increased and the layered MMT structure gradually collapsed and exfoliated. The MMT samples saturated with Ag + were treated with the sodium borohydride solutions to produce Ag 0 . The mean size of the Ag 0 crystallites of L 111 = 8.5(1) nm was estimated. The metal silver nanoparticles are assumed to be located at the layer surface and crystal edges of MMT.Keywords: adsorption, intercalation, silver, montmorillonite, nanoparticles IntroductionSilver is a noble metal with high electrical and thermal conductivity, chemical inertness to oxygen and many other gases and chemicals, photosensitivity to visible, X-ray and gamma-ray wavelengths in the electromagnetic spectrum, and also having catalytic and antibacterial properties. All these features have been widely used in many industrial applications. In the last few years, an effort of many basic research and application research laboratories has been focused on preparation of nanosize particles, which are known for their excellent physical and chemical properties. The two last mentioned papers describe silver reduction on silicates with layered structures (phyllosilicates). Their interlayer spacing serves as a nanoreactor, in which nanoparticles could form. The aim of this work was to investigate the adsorption of silver cations on montmorillonite, which seems to be capable of silver nanoparticles fabrication. Experimental ReagentsThe used chemicals were of ...

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The Role of Surface Heterogeneity in Adsorption

Cited by 166 publications

References 10 publications

Sorption of Trace Constituents from Aqueous Solutions Onto Secondary Minerals. I. Uranium

Sorption of Trace Constituents from Aqueous Solutions Onto Secondary Minerals. I. Uranium

Effective removal of radioactive 90Sr by CuO NPs/Ag-clinoptilolite zeolite composite adsorbent from water sample: isotherm, kinetic and thermodynamic reactions study

Study of silver adsorption on montmorillonite

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