Article
The effect of the pore structure and zeta potential of porous polymer monoliths on separation performance in ionexchange mode
Department of Chemical Engineering, University of Missouri, Columbia, Missouri, United States
Journal of Separation Science (Impact Factor: 2.74). 03/2007; 30(5):64857. DOI: 10.1002/jssc.200600421 Source: PubMed
ABSTRACT
Most often, in bioseparations involving charged macromolecules, the chromatographic systems have low Reynolds and high Peclet numbers. For such systems, an expression is developed and presented in this work for evaluating the throughput in polymeric monoliths where ionexchange adsorption occurs, as a function of (i) the pressure drop along the length of the monolith, (ii) the functional form and width of the throughporesize distribution of the monolith, and (iii) the magnitude of the zeta potential on the surface of the throughpores of the monolith. Gaussian and lognormal throughporesize distributions whose mean throughporesize and standard deviation values are based on experimentally measured throughporesize distribution data by mercury porosimetry employed on polymeric monoliths are used in this work, and their effect on the throughput relative to that obtained from a polymeric monolith having a uniform throughporesize distribution is studied for different values of the ratio of the standard deviation to the mean throughporesize. The results indicate that relatively modest increases in the throughput, when compared with the throughput that could be achieved in a polymeric monolith having a uniform throughporesize distribution, could be obtained in polymeric monoliths having disperse throughporesize distributions, and the magnitude of the increase becomes larger when the disperse distribution is skewed to larger throughpore sizes. Furthermore, the results of this work indicate that, under certain conditions, relatively modest increases in the throughput of a charged analyte could also be achieved by altering the value of the zeta potential on the surface of the throughpores of the monolith. Due to the difficulties inherent in controlling the functional form and width of the throughporesize distribution during the synthesis of polymeric monoliths, it would appear to be more practical to increase the value of the throughput of a charged analyte by altering the value of the zeta potential through prudent selection of the ionexchange surface functional groups and finetuned with the pH of the mobile phase. Thus, for ionexchange chromatography systems, the zeta potential could be considered an important parameter for column designers and operators to manipulate, since its alteration could increase the throughput of a charged analyte in polymeric monoliths or in columns packed with charged particles.

 "(2) and (3) is equal to the sum of p w,I and p in,I (P I = p w,I + p in,I ). The dustygas model has the major advantage of not requiring detailed information [38] [39] [40] [41] about the porous structure of the dried layer I; if one has a rather detailed information of the pore structure of the dried layer I obtained from highresolution optical microscopy [42] [43] [44] methods, then pore network theory [27] [28] [29] could be used to determine even more accurately the transport of heat and mass in the porous dried layer I. An estimate for the value of Darcy's flow permeability, C 01 could be obtained from the Blakeâ€“Kozeny correlation [21] "
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