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Intraparticle transport of sulfonated alkylbenzenes in a porous solid: Diffusion with nonlinear adsorption
Author(s) -
Weber Walter J.,
Rumer Ralph R.
Publication year - 1965
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr001i003p00361
Subject(s) - adsorption , diffusion , aqueous solution , mass transfer , thermodynamics , molecular diffusion , porous medium , chemistry , materials science , langmuir , porosity , chemical engineering , chromatography , organic chemistry , metric (unit) , physics , operations management , engineering , economics
Molecular diffusion is one of several phenomena contributing to establishment of rates of transfer of adsorbed materials from the exterior sites of a porous adsorbent to surfaces bounding inner pore spaces. For many applications of adsorption and ion exchange the rate of intraparticle transport in turn governs the over‐all rate of removal of solute from solution. The present work represents an approach to partial characterization of intraparticle transport kinetics by separation and evaluation of component molecular diffusion parameters. Data have been collected for rates of adsorption in several dilute, aqueous, single‐solute experimental systems, each comprised of a linear‐chain sulfonated alkylbenzene in micromolar concentration as the adsorbate and porous granular carbon as the absorbent. From measurements of rate of removal of solute from bulk solution for each system, and from separate measurements of adsorption isotherms, values for the corresponding coefficients of molecular diffusion have been calculated by numerical integration of the conservation of diffusing mass equation, incorporating an expression for simultaneous adsorption according to the nonlinear Langmuir monolayer model for adsorption. Calculated values for the coefficients of diffusion for the respective solutes, of the order of 10 −5 −10 −7 square centimeter per second, derived from measurements in the experimental systems, agree with values cited in the literature for the same and similar solutes measured in aqueous solution. This accordance indicates that the postulated model for intraparticle transport may be valid for description of the rate‐limiting process in agitated nonflow systems similar to those from which the experimental data have been derived. The technique further permits reduction of experimental data to a common parameter to facilitate system‐to‐system comparisons.