Estimating the pore size distribution of activated carbons from adsorption data of different adsorbates by various methods

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• 作者：Gauden ; Piotr A. ; Terzyk ; Artur P. ; Rychlicki ; Gerhard ; Kowalczyk ; Piotr ; Cwiertnia ; Magdalena S. ; et. al.
• 关键词：Adsorption ; Active carbon ; Microporosity ; Pore width ; The Horvath&ndash ; Kawazoe theory ; DFT ; The Nguyen&ndash ; Do model ; Potential theory ; Calorimetry ; Thermodynamics of adsorption ; Molecular sieve effect
• 刊名：Journal of Colloid and Interface Science
• 出版年：2004
• 期刊代码：125_00219797
• 类别：ch
• 出版时间：May 1, 2004
• 卷：273
• 期：1
• 页码：39-63
• 文件大小：693 K

摘要

Experimental adsorption isotherms of four adsorbates (N₂, Ar, C₆H₆, and CCl₄) as well as adsorption enthalpy (C₆H₆ and CCl₄) measured on two strictly microporous carbons are used to evaluate the porosity of adsorbents (i.e., pore size distributions (PSDs) and average pore diameter (L_av)). The influence of the diameter of adsorbates (d_A) as well as of the temperature (T) is analyzed in order to explain the differences or similarities between the above-mentioned quantities for all systems. Proposed previously, the general relationships between the parameters of the Dubinin–Astakhov (DA) isotherm equation (the characteristic energy of adsorption (E₀) and the exponent of this equation (n)) and the average slit-width of carbon micropores are investigated. Moreover, the thermodynamic verification of the Horvath–Kawazoe (HK) theory and the ND model is presented based on data of the adsorption and enthalpy of adsorption of benzene and carbon tetrachloride on two carbons. Finally, the pore diameters calculated from calorimetry data using the Everett and Powl method and those calculated applying the recently developed equations are compared. In our opinion the change of apparent PSD should be monitored by performing a series of isotherm measurements from high (equal and higher than room temperature) to low temperatures (ca. 77.5 K) as was presented in the current study. Moreover, the analysis of the experimental data leads to the conclusion that the entropy of C₆H₆ and CCl₄ can approach to the values characteristic of quasi-solid (a partially ordered structure). Therefore, this behavior of the adsorbate should be taken into consideration in the theoretical assumptions of model and its thermodynamic verification.