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首页> 外文期刊>Journal of Chemical Technology & Biotechnology >Solute transport in non-aqueous nanofiltration: effect of membrane material
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Solute transport in non-aqueous nanofiltration: effect of membrane material

机译：非水纳米过滤中的溶质迁移：膜材料的作用

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Nanotiltration experiments in methanol and ethanol were carried out for six reference components with different molecular weights (MW 228-880) and polarities (log P 0-12). The contribution of diffusion to solute transport, calculations based on results from cell diffusion experiments, was found to be only 1-7%; solute transport occurs mainly by convection. Furthermore, it was found that solute transport is influenced by solute-solvent-membrane interactions. Solvent-solute interactions (solvation) cause a different effective solute diameter in each solvent: it is smaller in ethanol than in methanol, resulting in lower rejections in ethanol than in methanol. Solute rejection increases with increasing molecular size (for components with similar polarity). Solute-membrane interactions were expressed in polarity terms and charge effects. A decrease of the rejection with decreasing solute polarity (for components with similar MW) was observed. Since non-polar components (high log P) are exposed to smaller repulsion forces from the polymeric membrane material, the resistance against solute permeation is lower for these components. The solvent-membrane interactions were found to result in solvation of the pore wall; the degree of membrane solvation is different for each solvent. It is determined by the affinity between the solvent and the membrane, and by the molecular size of the solvent. In ethanol, hydrophilic membranes show a larger drop in solute rejection than hydrophobic membranes. The differences in solvent-membrane affinity (measured by contact angle) are much smaller for the first membranes, and therefore pore wall solvation decreases with increasing solvent size. Hydrophobic membranes have a much larger affinity for ethanol than for methanol, leading to stronger interactions, but undergo competitive forces due to the larger solvent size. Therefore, the difference in degree of solvation and effective pore diameter is less pronounced. Based on these three observed or postulated interactions, rejections of all six reference solutes in methanol and ethanol could be explained. (c) 2005 Society of Chemical Industry.
机译：在甲醇和乙醇中对分子量（MW 228-880）和极性（log P 0-12）不同的六个参比成分进行了纳米倾斜实验。根据细胞扩散实验的结果计算，扩散对溶质迁移的贡献仅为1％-7％;溶质运输主要通过对流发生。此外，已发现溶质运输受溶质-溶剂-膜相互作用的影响。溶剂-溶质相互作用（溶剂化）在每种溶剂中导致不同的有效溶质直径：乙醇中的溶质直径小于甲醇中的溶质直径，因此乙醇中的截留率低于甲醇中的截留率。溶质截留率随分子大小的增加而增加（对于具有相似极性的组分）。溶质-膜相互作用用极性和电荷效应表示。观察到随着溶质极性的降低（对于具有相似MW的组分）排斥的降低。由于非极性组分（高log P）暴露于来自聚合物膜材料的较小排斥力，因此这些组分的抗溶质渗透性较低。发现溶剂-膜的相互作用导致孔壁的溶剂化。每种溶剂的膜溶剂化程度不同。它由溶剂和膜之间的亲和力以及溶剂的分子大小决定。在乙醇中，亲水膜比溶质膜的溶质截留率下降幅度更大。对于第一膜，溶剂-膜亲和力的差异（通过接触角测量）要小得多，因此孔壁溶剂化会随着溶剂尺寸的增加而降低。疏水膜对乙醇的亲和力比对甲醇的亲和力大得多，从而导致更强的相互作用，但由于溶剂尺寸较大，因此承受竞争力。因此，溶剂化度和有效孔径的差异不太明显。基于观察到的或假定的这三种相互作用，可以解释甲醇和乙醇中所有六种参考溶质的排斥。 （c）2005年化学工业协会。

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