Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes), Rennes, France.
Université Libanaise, Laboratoire de Biotechnologie Appliquée: Biomolécules, Biothérapies et Bioprocédés du Centre AZM pour la Recherche en Biotechnologie et ses Applications, Beyrouth, Lebanon.
Environ Technol. 2020 Jun;41(15):1950-1979. doi: 10.1080/09593330.2018.1552724. Epub 2018 Dec 20.
Ultrafiltration (UF) is a sustainable membrane separation technique. It could be useful for the concentration/purification of bio-sourced molecules that are extracted either by pure ethanol or by water/ethanol mixtures. Nevertheless, the process optimization requires an in-depth understanding of the transfer mechanisms of solute through membranes, especially for charged solutes, that are nowadays not sufficiently documented. Previous studies achieved in aqueous media have shown that the rejection of charged solutes by an UF membrane involves at least three mechanisms: convection, diffusion and electrostatic interactions. The present study aims at a systematic analysis of the transfer mechanisms of a model protein (lysozyme) in water/ethanol mixtures (100/0-70/30 v/v) during UF by a zirconia inorganic membrane. The influence of the pH varying in the 4-9 range and of the ionic strength (I) is also discussed. The ionic strength I can be adjusted by addition of an indifferent electrolyte (NaCl) only aiming at the screening of the electrostatic interactions or by addition of a selectively adsorbed electrolyte(KHPO) that is able to change the isoelectric pH of the protein and thus to modulate the electrostatic interactions in a different way when compared to NaCl. Of course, both salts have an impact on the protein rejection in UF. The results are analysed using the CDE model previously developed in our group to explain the behaviour of a single protein during UF in water and accounting for convection, diffusion and electrophoretic migration. The applicability of the CDE model in water/ethanol mixtures up to 70/30 v/v is finally shown.
超滤 (UF) 是一种可持续的膜分离技术。它可以用于浓缩/纯化通过纯乙醇或水/乙醇混合物提取的生物来源分子。然而，该过程的优化需要深入了解溶质通过膜的传递机制，特别是对于带电荷的溶质，目前这方面的文献还不够充分。以前在水介质中进行的研究表明，UF 膜对带电荷溶质的排斥至少涉及三种机制：对流、扩散和静电相互作用。本研究旨在通过氧化锆无机膜系统分析在水/乙醇混合物（100/0-70/30 v/v）中模型蛋白（溶菌酶）在 UF 过程中的传递机制。还讨论了 pH 值（4-9 范围内）和离子强度 (I) 的影响。离子强度 I 可以通过添加非电解质（NaCl）来调节，仅用于屏蔽静电相互作用，也可以通过添加选择性吸附的电解质 (KHPO) 来调节，后者能够改变蛋白质的等电 pH 值，从而与 NaCl 相比以不同的方式调节静电相互作用。当然，这两种盐都会影响 UF 中的蛋白质截留率。使用我们小组以前开发的 CDE 模型对结果进行分析，该模型用于解释在水中 UF 过程中单种蛋白质的行为，并考虑了对流、扩散和电泳迁移。最后还展示了 CDE 模型在水/乙醇混合物中高达 70/30 v/v 的适用性。
