Kinetics of sorption processes in polymer gels
Kinetic features of sorption process in polymers gels with complicated supermolecular structure have been analyzed. The mechanism of parallel diffusion was suggested to describe transfer processes which consist of several partial ones carried out simultaneously in different structure elements. Each structure region is characterized by own diffusion coefficient. In this case, apparent diffusion coefficient of the transfer process as a whole is a function of time D(t). The different averages of diffusion coefficient and ultimate concentration of sorbate can be obtained, using the initial rate of process and extrapolation D(t)t=0. These values depend on averaging type allow to relate the sorption kinetics departures from Fick’s law because of heterogeneity of polymer structure or other reasons (e.g., relaxation retardation of diffusion). The experimental data were treated in framework of this model. As a result, it was shown that the approach is convenient to determine the mechanism of sorption processes in heterogeneous polymer structures.
Key wordsSorption kinetics diffusion polymer supermolecular structure
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