Preparation parameters influencing the performance of SRNF membranes cast from polyimide solutions via SEPPI

作者：Vandezande Pieter; Gevers Lieven E M; Jacobs Pierre A; Vankelecom Ivo F J^*

来源：Separation and Purification Technology, 2009, 66(1): 104-110.

DOI：10.1016/j.seppur.2008.11.010

• Polyimide
• Solvent resistant nanofiltration
• Emulsions
• Solidification of emulsified polymer solutions via phase inversion
• Membrane post-treatment

Asymmetric nano-sized zeolite-filled polyimide membranes, prepared through the recently reported Solidification of Emulsified Polymer solutions via Phase Inversion (SEPPI) method, were applied in solvent resistant nanofiltration (SRNF). Thanks to the introduction of a short evaporation step prior to coagulation of the cast films, SEPPI allowed the synthesis of highly selective membranes with acceptable solvent fluxes in the separation of rose Bengal (RB) from 2-propanol (IPA). Addition to the casting solution of an organic suspension containing nano-sized silicalite-1 particles had a clear influence on membrane performance as a gradual transition from relatively open towards more dense membranes was observed. This transition coincided with a remarkable morphology change from finger-like to sponge-like membrane structures. An evaporation step of 90 s and an alternative post-treatment, involving solvent exchange coupled to mineral oil impregnation, allowed a significant performance increase of the most promising SEPPI membrane, with IPA permeances around 0.75 l m(-2) h(-1) bar(-1) and RB rejections up to 99%. The performance of the optimized SEPPI membrane compared favourably to the best commercial SRNF membranes, not only in the RB/IPA separation but also in other solvent/solute systems,while its specific structure resulted in increased compaction resistances. Molecular weight cut-off (MWCO) measurements in IPA and hexane, using low molecular weight dyes and alkanes, respectively, revealed MWCO values around 380 and 730 g/mol for this membrane.

• 出版日期2009-4-7