TY - JOUR
T1 - Organic solvent mixture separation during reverse osmosis and nanofiltration by a perfluorodioxole copolymer membrane
AU - Chau, John
AU - Sirkar, Kamalesh K.
N1 - Funding Information:
Reverse osmosis experiments and nanofiltration studies for solvent exchange were carried out using two different test cells. Most of the OSRO studies were carried out [12] in a 25 mm s. steel Holder (Model XX4502500, MilliporeSigma, Billerica, MA) having an effective membrane area in the cell of ~1.8 cm2. Each membrane sample punched out of a large flat sheet was supported by a porous s. steel disk and sealed by a PTFE O-ring. This cell was used for nanofiltration studies with mixed organic solvents as well. A much larger 300-mL cylindrical stirred cell (Model HP 4750, Sterlitech, Kent, WA) driven by N2 gas pressure and having a stainless steel support disk and EPDM O-rings was also used. The membrane area in this cell is 14.6 cm2.John Chau carried out these studies at the Otto York Department of Chemical and Materials Engineering, New Jersey Institute of Technology. We acknowledge Compact Membrane Systems, Delaware, USA for donating ePTFE-supported 0.6 μm thick CMS-7 membranes.
Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2021/1/15
Y1 - 2021/1/15
N2 - Highly selective separation of one organic solvent from its mixture with another organic solvent by reverse osmosis will be very useful. Using a 1.67 μm thick film of a particular variety of a glassy amorphous copolymer, perfluoro-2,2-dimethyl-1,3-dioxole copolymerized with tetrafluoroethylene, (PDD-TFE), supported on an e-PTFE support, organic solvent reverse osmosis (OSRO) separations of a number of types of binary organic solvent mixtures were studied. A few studies employed a 0.6 μm thick film of the same copolymer variety designated CMS-7. The feed pressures were varied between 1000 and 5000 kPa; most of the data involved 2500–3500 kPa. Different types of solvent mixtures were studied (similar classes mentioned together): ethanol-NMP, ethanol-dimethylsulfoxide (DMSO); methanol-DMSO, methanol-NMP; toluene-methanol, toluene-N-Methyl-2-pyrrolidone (NMP), toluene-dimethylformamide (DMF); heptane-dodecane; heptane-ethanol. In quite a few cases, a pure solvent was obtained as permeate; the permeate flux could be as much as 3.5 L/m2-hr depending on the feed composition and pressure. Since this behavior is unusual in reverse osmosis, mixture sorption studies were implemented. Mixture sorption data of various mixtures in the copolymer show exclusive sorption by the species showing up as the pure permeate under certain conditions. These and other observed OSRO permeation rate and sorption behavior in the perfluoro-copolymers explain the basis for such extraordinary selectivity for quite a few systems. To illustrate OSRO-facilitated solvent-exchange in organic solvent nanofiltration, studies were carried out also to retain the dye Oil Blue N using the following binary solvent mixtures: toluene-NMP; methanol-NMP. These and other potential applications of highly selective OSRO have been discussed.
AB - Highly selective separation of one organic solvent from its mixture with another organic solvent by reverse osmosis will be very useful. Using a 1.67 μm thick film of a particular variety of a glassy amorphous copolymer, perfluoro-2,2-dimethyl-1,3-dioxole copolymerized with tetrafluoroethylene, (PDD-TFE), supported on an e-PTFE support, organic solvent reverse osmosis (OSRO) separations of a number of types of binary organic solvent mixtures were studied. A few studies employed a 0.6 μm thick film of the same copolymer variety designated CMS-7. The feed pressures were varied between 1000 and 5000 kPa; most of the data involved 2500–3500 kPa. Different types of solvent mixtures were studied (similar classes mentioned together): ethanol-NMP, ethanol-dimethylsulfoxide (DMSO); methanol-DMSO, methanol-NMP; toluene-methanol, toluene-N-Methyl-2-pyrrolidone (NMP), toluene-dimethylformamide (DMF); heptane-dodecane; heptane-ethanol. In quite a few cases, a pure solvent was obtained as permeate; the permeate flux could be as much as 3.5 L/m2-hr depending on the feed composition and pressure. Since this behavior is unusual in reverse osmosis, mixture sorption studies were implemented. Mixture sorption data of various mixtures in the copolymer show exclusive sorption by the species showing up as the pure permeate under certain conditions. These and other observed OSRO permeation rate and sorption behavior in the perfluoro-copolymers explain the basis for such extraordinary selectivity for quite a few systems. To illustrate OSRO-facilitated solvent-exchange in organic solvent nanofiltration, studies were carried out also to retain the dye Oil Blue N using the following binary solvent mixtures: toluene-NMP; methanol-NMP. These and other potential applications of highly selective OSRO have been discussed.
KW - Nonpolar solvent
KW - Perfluorodioxole copolymer membrane
KW - Polar aprotic/protic solvent
KW - RO separation of organic solvent mixtures
KW - ePTFE-supported composite membrane
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U2 - 10.1016/j.memsci.2020.118663
DO - 10.1016/j.memsci.2020.118663
M3 - Article
AN - SCOPUS:85090750758
SN - 0376-7388
VL - 618
JO - Journal of Membrane Science
JF - Journal of Membrane Science
M1 - 118663
ER -