The equation of vapor-phase sorption on heterogeneous surfaces with local Guggenheim–Anderson–De Boer model

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• 作者：Artem A. Mishchenko ; Nikolay D. Yakimov ; Konstantin A. Potashev ; Vladimir A. Breus ; Irina P. Breus
• 关键词：Vapor-phase sorption ; Heterogeneous surfaces ; Sorption energy distribution function ; MGAB equation
• 刊名：Colloids and Surfaces A ; Physicochemical and Engineering Aspects
• 出版年：2007
• 期刊代码：22_09277757
• 类别：ch
• 出版时间：15 March 2007
• 卷：296
• 期：1-3
• 页码：182-190
• 文件大小：428 K

摘要

Recently, we proposed a new four-parametric MGAB equation (modified Guggenheim–Anderson–De Boer equation, GAB) for fitting of experimental isotherms of vapor-phase sorption on geosorbents. In the present study, the theoretical meaning of MGAB equation was elucidated. For this purpose, the properties of the equation of multilayer adsorption on a heterogeneous surface with local characteristics described by GAB model and Zeldovitsh–Roginskiy energy distribution function ρ() were derived and the satisfaction of MGAB equation with these properties was shown. MGAB model has two parameters connected with GAB model: v_m is the monolayer sorption capacity and k is the constant of the multilayer sorption, as well as two parameters of sorption energy distribution function ρ(): α, characterizing heterogeneity of ρ() and C₀, reflecting energy baseline. The influence of parameters α and C₀ on the shape of both ρ() and model sorption isotherm was established. The applicability of MGAB model for the description of surface heterogeneity of a natural sorbent by example of 13 different sorbate–sorbent systems dried and moistened has been discussed. For these systems equilibrium sorption isotherms were measured, corresponding energy distribution functions ρ() were calculated, and obtained α values were compared. On the whole, the differences in α values responded to the real tendencies of heterogeneity changes in these systems.