Kinetic derivation of common isotherm equations for surface and micropore adsorption

Afonso, Rui; Gales, Luı́s; Mendes, Adélio

doi:10.1007/s10450-016-9803-z

Cited by 27 publications

(17 citation statements)

References 15 publications

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“…It is later used for the derivation of the BET, 36 the GAB, 39 and the Fowler-Guggenheim isotherm. 52 Alternatively the derivation of the isotherms is based on classical thermodynamics or statistical thermodynamics. 53 The first example of the latter concept has been presented by Fowler and Guggenheim in their deduction of a sigmoidal isotherm.…”

Section: Introductionmentioning

confidence: 99%

Modeling of type IV and V sigmoidal adsorption isotherms

Buttersack

2019

Phys. Chem. Chem. Phys.

163

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Section: Introductionmentioning

confidence: 99%

Modeling of type IV and V sigmoidal adsorption isotherms

Buttersack

2019

Phys. Chem. Chem. Phys.

163

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“…This difference of interaction depends on the strength of the adsorbate with the surface of adsorbent and the strength between adsorbate molecules. Fowler–Guggenheim localizes lateral interactions of adsorbed molecules and is derived from the following equation (Afonso et al, 2016):

K C_{normale} = \frac{normalθ}{1 - θ} \exp (- c θ)

with

c = \frac{2 W}{R T}

where K represents the Fowler–Guggenheim equilibrium constant (L mg −1 ), θ represents the fractional coverage, R represents the universal gas constant (kJ mol −1 K −1 ), T represents the temperature (K), W represents the interaction energy between adsorbed molecules (kJ mol −1 ), and c represents a system‐specific constant.…”

Section: Methodsmentioning

confidence: 99%

“…The Hill–de Boer model describes mobile and lateral interactions of the distributed adsorbates and is given by (Afonso et al, 2016)

C_{normale} = K_{2} \frac{normalθ}{1 - θ} \exp (\frac{normalθ}{1 - θ} - K_{1} θ)

where K 2 (L mmol −1 ) represents a parameter connected to the gas–solid interaction, and K 1 (kJ mol −1 ) represents the Hill–de Boer constant. θ represents a function of two parameters.…”

Section: Methodsmentioning

confidence: 99%

“…This difference of interaction depends on the strength of the adsorbate with the surface of adsorbent and the strength between adsorbate molecules. Fowler-Guggenheim localizes lateral interactions of adsorbed molecules and is derived from the following equation (Afonso et al, 2016):…”

Section: Fowler-guggenheim Modelmentioning

confidence: 99%

“…The Hill-de Boer model describes mobile and lateral interactions of the distributed adsorbates and is given by (Afonso et al, 2016)…”

Section: Hill-de Boer Modelmentioning

confidence: 99%

See 2 more Smart Citations

Using Recycled Concrete as an Adsorbent to Remove Phosphate from Polluted Water

Tang²,

Zhang

et al. 2019

J of Env Quality

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Phosphate pollution remains a significant hazard to terrestrial and aquatic ecosystems. We developed an economical and efficient method for phosphate adsorption on waste construction concrete modified with seawater. Compared with raw concrete materials, the phosphate adsorption capacity of seawater‐modified waste concrete was highly efficient, especially at low phosphate concentrations. The inflection point for seawater‐modified concrete was 0.66 and 1.22 mg L−1 for the raw material. The relative phosphate adsorption was 4.64 and 2.39 mg g−1, respectively. Phosphate removal was >90% over a pH range of 3 to 11 for the raw and modified materials. Chemical and physical analysis of the modified concrete indicated that Ca and Mg particles were uniformly sequestrated on the surface, and Ca was the determinant controlling phosphate uptake. Phosphate adsorption isotherms fit well using the Freundlich, Temkin, Elovich, Fowler–Guggenheim, and Hill–de Boer models and indicated that intermolecular forces in the concrete particles were enhanced by calcium oxides from seawater. This method can efficiently remove phosphate from polluted water and repurposes waste construction concrete. Core Ideas Phosphate adsorption capacity of modified waste concrete was highly efficient at low phosphate. Phosphate removal was >90% over a pH range of 3 to 11 for the raw and modified materials. Calcium was the determinant controlling phosphate uptake for seawater‐modified concrete. Intermolecular forces in the concrete particles were enhanced by calcium oxides from seawater.

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Microkinetic Barriers of the Oxygen Evolution on the Oxides of Iridium, Ruthenium and their Binary Mixtures

et al. 2022

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The performance of electrocatalytic water splitting in polymer electrolyte membrane electrolysis is substantially determined by the microkinetic processes of the oxygen evolution reaction (OER). Even highly active catalysts such as the nanoparticulated transition metal oxides IrO2, RuO2 and their mixtures, IrxRu1−xO2, exhibit overpotentials up to several hundreds of millivolts. The surface of the oxide mixtures IrxRu1−xO2 is found to consist of actives sites of both Ir and Ru on which the OER mechanism is processed independently and at different overpotentials. By applying microkinetic modelling and parameterization via cyclic voltammograms we show that there is a correlation between performance and the relative Ir content, that can be explained by two different deprotonation steps. These are in particular the formation of the adsorbate species *OOH on rutile RuO2 and *OO on IrO2. The respective free reaction energies are quantified to 1.44 eV and 1.58 eV, which are the highest values of the process and thus determining the overpotential. The additional finding of adsorbed oxygen *O covering >40 % of the active sites during the OER suggests that subsequent water adsorption is the major performance limiting step. Finally, a synergetic effect between both active sites on the binary transition metal oxides is identified: the respective other metal lowers the potential determining reaction energy on the Ru or Ir active site. This insight into the surface processes on Ir and Ru binary oxides forms the basis for deeper understanding of the active sites for further OER catalyst development.

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Kinetic derivation of common isotherm equations for surface and micropore adsorption

Cited by 27 publications

References 15 publications

Modeling of type IV and V sigmoidal adsorption isotherms

Modeling of type IV and V sigmoidal adsorption isotherms

Using Recycled Concrete as an Adsorbent to Remove Phosphate from Polluted Water

Microkinetic Barriers of the Oxygen Evolution on the Oxides of Iridium, Ruthenium and their Binary Mixtures

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