REI-YOUNG AMOS WU, Purdue University


Adsorption of BSA lysozyme and mixture of the two proteins from aqueous solution onto activated carbon and adsorption of BSA onto phenolic resin has been studied to develop design parameters for protein adsorption and to evaluate the effective diffusivity of the proteins. The findings then are used as the theoretical basis for the study of processes such as enzyme immobilization and removal of proteinaceous material from corn syrup. The effects of pH, buffer concentration and temperature are investigated for each adsorption process. The adsorption of proteins onto both adsorbents was found to be irreversible in nature through desorption study and isotherm development. The adsorption maximum is near the isoelectric point of protein regardless of the type of adsorbent used. The carbon seemed to have the same adsorption capacity for BSA and lysozyme; being 26 mg/g carbon and 27 mg/g carbon, respectively. One possible explanation is to include a steric argument in monolayer adsorption model. The correspondent occupied surface area is 10.4 m('2)/g carbon for BSA and 13.2 m('2)/g carbon for lysozyme. More protein was adsorbed on phenolic resin; the adsorption capacity was 340 mg/g resin. The calculated capacity of resin for lactase was 1.8 g/g and the capacity of carbon for corn syrup protein is 4.6 mg/g assuming that surface coverage is the same as the model protein. The rate of protein adsorption onto porous material was found to be controlled by the pore diffusion process and the effective diffusion coefficient was evaluated with the shrinking core model. In general, there is little difference between the effective diffusion coefficients calculated using infinite-bath approach and finite-bath approach. In the proteins/carbon system, the effective diffusivity was about 1/17 of the bulk diffusivity; in the BSA/resin system, the effective diffusion coefficient was about 1/135 of the bulk. The effect of temperature on the effective diffusivity can be described by Stokes-Einstein equation. The knowledge of the pure protein adsorption was combined with the molecular weight of interested proteins to successfully predict the adsorption capacity of adsorbent and the effective diffusivity of the proteins in the adsorbent for lactase immobilization and corn syrup removal.



Subject Area

Chemical engineering

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