Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7043854 | Separation and Purification Technology | 2018 | 39 Pages |
Abstract
Solvent swelling of polymers is of major importance in organic solvent nanofiltration (OSN) affecting membrane rejection of 200-1000+â¯Da solutes. A selected perfluoro type amorphous glassy copolymer, perfluoro-2,2-dimethyl-1,3-dioxole copolymerized with tetrafluoroethylene (PDD-TFE), is completely insoluble in all solvents except perflourinated solvents; further it showed very little swelling in solvents that are not of the perfluorinated type. Pure component permeation flux for a particular variety of this copolymer, CMS-7, was measured with a wide variety of solvents for two membrane thicknesses, 1.67â¯Âµm and 0.6â¯Âµm, in a composite form supported on a porous ePTFE substrate. The feed pressure range was 1000-3000â¯kPa. The solvents included methanol, ethanol, ethyl acetate, n-heptane, tetrahydrofuran (THF), toluene, dimethylsulfoxide (DMSO); n-heptane showed much higher flux than the rest. Successful OSN was demonstrated with high solute rejection in methanol solutions of two dye solutes Safranin O (MW, 351â¯Da) and Brilliant Blue R (MW, 826â¯Da). Rejection for Safranin O varied between 94% and 97% depending on the pressure and membrane thickness; that for Brilliant Blue R varied in the range of 97-99.8%. Successful OSN was also demonstrated with Safranin O in THF with solute rejection varying between 94% and 97%. Permeation behaviors of various mixtures of two solvents, toluene and n-heptane, were studied. The measured values of very limited extent of sorption of a variety of organic solvents in 25â¯Âµm thick dense samples of this and a related perfluoro type copolymer, CMS-3, were employed to explain the observed behavior.
Keywords
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Filtration and Separation
Authors
John Chau, Prithish Basak, Jasmine Kaur, Yucheng Hu, Kamalesh K. Sirkar,