Premium
Parallel transport of BSA by surface and pore diffusion in strongly basic chitosan
Author(s) -
Yoshida Hiroyuki,
Yoshikawa Motonobu,
Kataoka Takeshi
Publication year - 1994
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690401213
Subject(s) - thermal diffusivity , diffusion , chemistry , surface diffusion , bovine serum albumin , adsorption , analytical chemistry (journal) , fick's laws of diffusion , ion , ion exchange , thermodynamics , chromatography , physics , organic chemistry
The parallel transport of a protein by surface and pore diffusion within a highly porous ion exchanger is studied by measuring equilibria and uptake curves for adsorption of bovine serum albumin (BSA) on two different strongly basic chitosan ion exchangers (hard gels): Ch‐2503 and Ch‐2507 at pH 6.9 and 298 K. Experimental equilibrium isotherms are correlated by the Langmuir equation. Intraparticle effective diffusivities of BSA (D eff ) are determined from the homogeneous Fickian diffusion model, increasing with the bulk phase concentration increase of BSA (C 0 ). It suggests the existence of parallel diffusion. The surface diffusivity D S for the parallel diffusion model is determined from the D eff , and D S = 0.47 × 10 −13 m 2 · s −1 (Ch‐2507) and 2.4 × 10 −13 m 2 · s −1 (Ch‐2503) were obtained. Pore diffusivities based on the pore diffusion control (D′ P ) are obtained by matching the shrinking core model with the experimental uptake curves. D′ P decreases with increasing C 0 . Since D′ P in Ch‐2507 is constant when C 0 ≥ 1 kg·m −3 , the constant value 2.7 × 10 −11 m 2 · s −1 is taken as the accurate pore diffusivity (D P ). As D′ P in Ch‐2503 does not approach a constant value, D P = 1.0 × 10 −11 m 2 · s −1 is determined by matching the parallel diffusion model with the uptake data, and the model calculated using experimental values of D S and D P agrees reasonably well with the uptake data for Ch‐2507 and Ch‐2503. This theoretical approach may be applied not only for intraparticle diffusion of proteins but any adsorbates in porous materials.