Composite PDMS membrane with high flux for the separation of organics from water by pervaporation

The separation of ethanol−water could be cost-competitive using pervaporation in the production of renewable biomass ethanol, but the performance of the modified or unmodified polymeric membranes still is not satisfactory. For the purpose of improving the pervaporation performance of polymeric membranes, especially for flux, polydimethylsiloxane (PDMS) was deposited uniformly on the surface of tubular nonsymmetric ZrO2/Al2O3 porous ceramic supports. The as-prepared composite membranes were characterized by scanning electron microscopy (SEM), Fourier transform infrared-attentuated total reflectance (FTIR−ATR), and pervaporation experiments. The thickness of the PDMS layer formed atop the ZrO2 layer was on the order of 5−10 μm. In the ethanol−water pervaporation experiment, as the ethanol concentration increased, the total flux increased but the selectivity decreased. At the same time, with increasing operating temperature, the total flux of the composite membranes increased whereas the selectivity decrease...

Polydimethylsiloxane (PDMS)/Ceramic Composite Membrane with High Flux for Pervaporation of Ethanol−Water Mixtures

Optimization of preparation conditions for polydimethylsiloxane (PDMS)/ceramic composite pervaporation membranes using response surface methodology

Properties and separation performance of Ge-ZSM-5 membranes

Free volume and alcohol transport properties of PDMS membranes: Insights of nano-structure and interfacial affinity from molecular modeling

Hydrophobic composite membranes with a crosslinked poly(dimethylsiloxane)-poly(methyl hydrogen siloxane) selective layer were prepared by using a new laboratory made catalyst agent. The pervaporation separation of five organic solvent–water mixtures was carried out with these composite membranes, together with swelling experiments in the same feed mixtures. The volatile organic compounds employed were ethanol, methanol, 1-butanol, acetone, and ethyl acetate. The pervaporation and swelling experiments revealed that both the 1-butanol and the ethyl acetate solutions showed the highest affinity for the composite membrane. When these components were employed as feed solutions, the membranes showed both high selectivity and high permeation. Mechanical–dynamical experiments of swollen and nonswollen composite membranes were also performed. The relaxation spectra were analyzed in terms of the interaction of the components of the different mixtures with the composite membrane, and the free volume corresponding to the each sample was obtained. Once the membranes had reached an equilibrium swelling, a decrease in the free volume was observed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 546–556, 2001

Characterization of poly(dimethylsiloxane)‐poly(methyl hydrogen siloxane) composite membranes for organic water pervaporation separation

Novel hydrophobic composite membranes made of crosslinked poly(dimethylsiloxane) and poly(methyl hydrogen siloxane) (PDMS–PMHS) with various amounts of catalyst were prepared. Pervaporation experiments with water–ethanol mixtures revealed that an optimum ratio of catalyst to polymer base existed. Both swelling behavior and dynamic–mechanical properties of these silicone films were studied. The swelling experiments in different mixtures of ethanol and water determined that ethanol is preferentially sorbed and that the membranes are only capable to absorb a limited quantity of solvent. Equilibrium swelling data were also used in combination with the analysis of the viscoelastic relaxation of the swollen samples to obtain the dependence of the dynamic–mechanical properties of the silicone films on the quantity of permeants sorbed into the membrane. It was observed that the permselective parameters were related with the mobility of the chains and the free volume. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1424–1433, 2000

Swelling behavior of pervaporation membranes in ethanol–water mixtures

Low and high density commercial polyethylenes have been irradiated using a cobalt 60 source in order to receive doses in the range of zero and 100 Mrad. Irradiated and unirradiated specimens were subjected to dynamic mechanical analysis. The changes observed in the mechanical relaxation spectrum are associated with the modifications observed in the chemical structure and the morphological parameters involved in the exposure of the polyethylenes to γ-radiation.

Dynamic mechanical relaxations in annealed and irradiated polyethylenes

Hydrophobic pervaporation membranes made of cross-linked poly(dimethylsiloxane) (PDMS) and poly(methylhydrogensiloxane) (PMHS) were prepared to separate ethanol/water mixtures. It was found that the permselective parameters are related with the level of cross-linking. The final structure of the silicone films obtained by different performance conditions and the interaction between the silicone and the components of liquid mixtures were analyzed in terms of viscoelastic properties of silicone films.

Isabel Alcaina-Miranda

Papers

Characterization of poly(dimethylsiloxane)‐poly(methyl hydrogen siloxane) composite membranes for organic water pervaporation separation

Swelling behavior of pervaporation membranes in ethanol–water mixtures

Dynamic mechanical relaxations in annealed and irradiated polyethylenes

Swelling studies on pervaporation by dynamic-mechanical spectroscopy