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Extended Rate Constants Distribution (RCD) Model for Sorption in Heterogeneous Systems: 2. Importance of Diffusion Limitations for Sorption Kinetics on Cryogels in Batch

Institute of Chemistry, Far Eastern Branch of Russian Academy of Sciences, 159, prosp.100-letiya Vladivostoka, 690022 Vladivostok, Russia
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Received: 22 April 2020 / Revised: 10 May 2020 / Accepted: 13 May 2020 / Published: 14 May 2020
(This article belongs to the Special Issue Cryogelation and Cryogels 2.0)
Here we address the problem of what we can expect from investigations of sorption kinetics on cryogel beads in batch. Does macroporosity of beads indeed help eliminate diffusion limitations under static sorption conditions? Are sorption rate constants calculated using phenomenological kinetic models helpful for predicting sorption properties under dynamic conditions? Applying the rate constants distribution (RCD) model to kinetic curves of Cu(II) ions sorption on polyethyleneimine (PEI) cryogel and gel beads and fines, we have shown that diffusion limitations in highly swollen beads are very important and result in at least ten-fold underestimation of the sorption rate constants. To account for intraparticle diffusion, we have developed the RCD-diffusion model, which yields “intrinsic” kinetic parameters for the sorbents, even if diffusion limitations were important in kinetic experiments. We have shown that introduction of a new variable—characteristic diffusion time—to the RCD model significantly improved the reliability of sorption kinetic parameters and allowed prediction of the minimal residence time in column required for efficient uptake of the adsorbate under dynamic conditions. The minimal residence time determined from kinetic curves simulated using the RCD-diffusion model was in good agreement with experimental data on breakthrough curves of Cu(II) ion sorption on monolith PEI cryogel at different flow rates. View Full-Text
Keywords: polyethyleneimine; cryogel; sorption; sorption kinetic models; intraparticle diffusion; sorption dynamics; metal ions polyethyleneimine; cryogel; sorption; sorption kinetic models; intraparticle diffusion; sorption dynamics; metal ions
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MDPI and ACS Style

Malakhova, I.; Golikov, A.; Azarova, Y.; Bratskaya, S. Extended Rate Constants Distribution (RCD) Model for Sorption in Heterogeneous Systems: 2. Importance of Diffusion Limitations for Sorption Kinetics on Cryogels in Batch. Gels 2020, 6, 15. https://doi.org/10.3390/gels6020015

AMA Style

Malakhova I, Golikov A, Azarova Y, Bratskaya S. Extended Rate Constants Distribution (RCD) Model for Sorption in Heterogeneous Systems: 2. Importance of Diffusion Limitations for Sorption Kinetics on Cryogels in Batch. Gels. 2020; 6(2):15. https://doi.org/10.3390/gels6020015

Chicago/Turabian Style

Malakhova, Irina, Alexey Golikov, Yuliya Azarova, and Svetlana Bratskaya. 2020. "Extended Rate Constants Distribution (RCD) Model for Sorption in Heterogeneous Systems: 2. Importance of Diffusion Limitations for Sorption Kinetics on Cryogels in Batch" Gels 6, no. 2: 15. https://doi.org/10.3390/gels6020015

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