The Study on Pervaporation Behaviors of Dilute Organic Solution Through PDMS/PTFE Composite Membrane

Abstract

As an energy-efficient alternative to distillation, pervaporation has been widely combined with fermentation to remove organic compounds from their dilute solutions in a fermentation broth. In this work, the organic permselective composite membrane is prepared by coating polydimethylsiloxane (PDMS) cross-linked with n-heptane on the substrate of polytetrafluoroethylene(PTFE) membrane. The separation behavior is studied in different dilute organic solutions, which include acetone dilute solution, butanone dilute solution, cyclohexanone dilute solution, ethanol dilute solution, isopropanol dilute solution, n-butyl alcohol dilute solution, acetic acid dilute solution, and ethyl acetate dilute solution. Most of these solutions are main reaction products or by-products from fermentation process. The effects of solubility of organics in the membrane, molecular weight, and polarity of the organics on the pervaporation performance are investigated. The effects of operating temperature and organic concentration in the feed solutions on the performance of composite membrane are studied as well. The experimental results show that molecular volume has less influence than solubility and molecular polarity for these organic solvent. The selectivity of PDMS membrane to ethyl acetate is relative high due to good solubility and diffusion of ethyl acetate molecules in polymer.

Recovery of alcohols from water using polydimethylsiloxane–silica nanocomposite membranes: Characterization and pervaporation performance

“…Therefore, solubility and diffusivity of permeants through the membrane control permeation flux and selectivity. As mentioned, solubility parameter of PDMS is closer to that of IPA than those of ethanol and methanol,9, 41 then, the PDMS membrane is more selective to IPA compared with ethanol and methanol. Solubility parameter is a measure of affinity between polymer and solvent.…”

“…As observed, DS values in IPA‐water mixtures are higher than those in ethanol–water and methanol–water mixtures. This can be attributed to solubility parameter difference of IPA (23.6 (J/cm 3 ) 1/2 ), ethanol (26.2 (J/cm 3 ) 1/2 ), and methanol (29.7 (J/cm 3 ) 1/2 ) with PDMS (14.9 (J/cm 3 ) 1/2 ) membrane 9, 41. In other words, the less solubility parameter difference between IPA and PDMS membrane means that IPA molecules absorb into the membrane more easily compared with ethanol and methanol.…”

“…Solubility parameter is a measure of affinity between polymer and solvent. As the affinity between solvent and polymer enhances, the more solvent is absorbed inside the polymer and consequently permeation flux increases 41…”

Treatment of Wastewater Containing Volatile Organics Using Hollow Fibre PDMS-Polysulfone Membrane System:Recovery of Organics and Water Reclamation

“…Preparation of the thin PDMS membrane is desirable as the membrane thickness is inversely proportional to the flux. Various PDMS membranes supported on porous substrate have been prepared by different methods, such as PDMS-PTFE and PDMS-polystyrene composite membranes, by pouring the coating solution on membrane support 2,3 ; dip-coating preparation method of the PDMS membranes using various supports [4][5][6] and PDMS membrane preparation by solution casting technique [7][8][9][10][11][12] . It is difficult to coat thin PDMS layer, as the initial coating solution is viscous due to the cross-linking reaction between the pre-polymer liquid and cross-linker.…”

Joining the Un‐Joinable: Adhesion Between Low Surface Energy Polymers Using Tetrapodal ZnO Linkers

“…Similarly, cross‐linked PDMS (often used in backing paper of sticky labels)3 is, together with PTFE, among the materials with the lowest surface energy known to date 4. Due to their unique chemical and physical properties, the combination of these two materials is required for many applications, such as for membranes for pervaporation technology,5 biocompatible microelectronic and optofluidic devices,6 or in medical implants 7…”