• Proceedings of the Membrane Society of Korea Conference
• /
• 2004.05a
• /
• pp.98-101
• /
• 2004

Utilization of biomass resources has considerable contribution to the reduction of carbon dioxide emission. Ethanol is one of the biomass products and is used as an additive to gasoline in several countries. Conventional process to produce ethanol involves energy-intensive azeotropic distillation. Pervaporation (PV) or vapor permeation (VP) is considered to be an alternative separation process to the conventional process.(omitted)

• Proceedings of the Membrane Society of Korea Conference
• /
• 1993.04a
• /
• pp.52-53
• /
• 1993

The pervaporation behavior of EtOH/Water mixture through IPN membranes was predicted in this study. The pervaporation characteristics of single polymer membrane were modeled according to the "six-coefficients model" proposed by Brun. In the case of the IPN membrane, two models were proposed according to the phase structure of the IPN. For a uniphase membrane with no phase separation, the compositional average of the single polymer membrane was used. in the case of the phase separated IPN's two cases existed. The first was the island and sea model: in which one phase was continuous and the other was dispersed. The second was the co-continuous model where two continuous phases existed. For these cases, the permeation rate and the separation factor of the IPN membrane were calculated using the experimental sorption data and the cornponent polymer properties. Comparison with the experimental data indicated that these models could be used to predict the performances of IPN membranes depending on the morphology of the IPN.

• Macromolecular Research
• /
• v.11 no.3
• /
• pp.163-171
• /
• 2003

For the pervaporation of water-ethanol mixtures, new composite membranes having poly(acrylic acid)-poly (butyl methacrylate-co-methyl methacrylate) interpenetrati ng polymer network [PAA-P(BMA-co-MMA) IPN] skin layer supported on porous and crosslinked poly(BMA-co-MMA) were prepared. The morphology of the sub-layer of the composite membrane prepared in the presence of 60 wt% solvent showed cellular structure, on the other hand that of sublayer prepared in the presence of 70 wt% solvent presented very porous interconnected pore structure with macrovoids. Permeation rates of the composite membranes were largely influenced by the morphology of the sublayer. Separation factors increased with the increase of the degree of crosslinking of the PAA network. It was found that permeation rates could be increased by introducing anionic charges on carboxyl groups of the PAA. The permeation rate changes of the PAA-P(BMA-co-MMA) IPN composite membranes according to the feed compositions showed quite similar pattern with the swelling behavior in water-ethanol mixtures.

• Applied Chemistry for Engineering
• /
• v.9 no.4
• /
• pp.469-474
• /
• 1998

Poly (vinyl alcohol) (PVA) membranes crosslinked with poly (styrene-co-maleic anhydride) (PSMAn) have been prepared by the solution method. To investigate the separation behavior of the crosslinked PVA/PSMAn membranes in the pervaporation process, the selective sorption experiment and swelling measurements of the membranes in ethanol-water mixtures of 30~90 wt % ethanol contents were conducted with equipment that was able to measure the concentration and amount of the liquid absorbed in the membranes. The membranes prepared in this study exhibited good selectivity toward water component in sorption and permeation. Also, in the feed containing ethanol more than 50 wt %, the permeation selectivity of the membrane showed better correlation with the sorption selectivity than that with the swelling ratio changing toward the crosslinking content. This behavior was consistence with a solution-diffusion model correlating permeation and sorption selectivity, and led to the conclusion that the permeation selectivity was determined by sorption step rather than by diffusion step in the membrane.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.5
• /
• pp.687-693
• /
• 2004

Composite membranes with a titania layer were prepared by soaking-rolling method with the titania sol of nanoparticles formed in the sol-gel process and investigated regarding the vapor permeation of various organic mixtures. The support modification was conducted by pressing $SiO_2$ xerogel of 500 nm in particle size under 10 MPa on the surface of a porous stainless steel (SUS) substrate and designed the multi-layered structure by coating the intermediate layer of ${\gamma}-Al_2O_3$. Microstructure of titania membrane was affected by heat-treatment and synthesis conditions of precursor sol, and titania formed at calcination temperature of 300$^{\circ}C$ with sol of [$H^+$]/[TIP]=0.3 possessed surface area of 210 $m^2$/g, average pore size of 1.25 nm. The titania composite membrane showed high $H_2/N_2$ selectivity and water/ethanol selectivity as 25-30 and 50-100, respectively. As a result of vapor permeation for water-alcohol and alcohol-alcohol mixture, titania composite membrane showed water-permselective and molecular-sieve permeation behavior. However, water/methanol selectivity of the membrane was very low because of chemical affinity of permeants for the membrane by similar physicochemical properties of water and methanol.

• Proceedings of the Membrane Society of Korea Conference
• /
• 1996.10a
• /
• pp.86-87
• /
• 1996

IPN (Interpenetrating Polymer Network) is a mixture of two or more crosslinked polymers with physically interlocked network structures between the component polymers. IPN can be classified as an alloy of thermosets and has the characteristics of thermosets such as the thermal resistance and chemical resistance and also has the characteristics of polymer alloys with enhanced impact resistance and amphoteric properties. The physical interlocking during the synthesis restricts the phase separation of the component polymer with chemical pinning process, thus the control of morphology is possible through variations of the reaction temperature and pressure, catalyst concentration and crosslinking agent concentration. Finely dispersed domain structure can be obtained through IPN synthesis of polymer components with gross immiscibility. In membrane applications, particularly for the separation of liquid mixtures, crosslinked polymer component with specific affinity to the permeate is needed. With the presence of the permeant-inert polymer component, the mechanical strength and the selectivity of the membranes are enhanced by restricting the swelling of the transporting polymer component networks.

• Membrane Journal
• /
• v.18 no.3
• /
• pp.206-213
• /
• 2008

Poly(vinylidene fluoride) (PVDF) membrane surfaces were modified using surface modifying macromolecules (SMMs). The Zonyl BA-L as SMM was used and the various PVDF membranes containing 0 to 2 wt% SMM were prepared. The resulting membranes were characterized through SEM, contact angle measurements and pervaporation separation of water-ethanol system. SMM layers were created in the surface regions of PVDF membranes by SEM images and the contact angles were increased more than untreated PVDF membranes. The pervaporation was carried out at 50, 60 and $70^{\circ}C$, and the PVDF membranes containing 1 and 2 wt% SMM were used for 10, 20, 50 wt% water in the binary water/ethanol mixtures and pure water. PVDF/2 wt% Zrlnyl BA-L membrane showed the permeability 5.3 $g/m^2hr$ and separation factor 287 at $50^{\circ}C$ for water : ethanol = 10 : 50 solution.

• Membrane Journal
• /
• v.33 no.6
• /
• pp.377-382
• /
• 2023

In this study, a PEBAX/PVDF composite membrane was fabricated, and its pervaporation performance was tested in an ethanol/water mixture. In addition, we attempted to improve the pervaporation performance of the composite membrane by forming a ZIF-8 layer on the surface of the PVDF substrate. The thickness of selective layer was optimized by comparing the pervaporation performance depending on the PEBAX thickness. A pervaporation test was performed on the Ethanol/Water mixture. As a result, the composite membrane using PVDF substrate with ZIF-8 layer had a flux of 1.98 kg/m²h and separation factor of 3.88, showing higher values of both permeation flux and selectivity than the composite membrane using bare PVDF substrate.

• Korean Membrane Journal
• /
• v.6 no.1
• /
• pp.55-60
• /
• 2004

In recent years, an increasing interest in membrane technology has been observed in chemical and environmental industry. Membrane technology has advantages of low cost, energy saving and environmental clean technology comparing to conventional separation processes. Pervaporation is one of new advanced membrane technology applied for separation of azeotropic mixtures, aqueous organic mixtures, organic solvent and petrochemical mixtures. Sodium alginate composite membranes were prepared for the enhancement of long-term stability of pervaporation performance of water-ethanol mixture using pervaporation. Sodium alginate membranes were crosslinked with CaCl$_2$ and coated with polyelectrolyte chitosan to protect washing out of calcium ions from the polymer. The surface structures of PAN and hydrolysed PAN membrane were confirmed by ATR Fourier transform infrared (FT-IR). A field emission scanning electron microscopy (FE-SEM; Jeol 6340F) operated at 15 kV. Concentration profiles for Ca in the membrane surface and membrane cross-section were taken by an energy dispersive X-ray (EDX) analyser (Jeol) attached to the field emission scanning electron microscopy (Jeol 6340F). Pervaporation experiments were done with several operation run times to investigate long-term stability of the membranes.

• Journal of Microbiology and Biotechnology
• /
• v.23 no.7
• /
• pp.942-952
• /
• 2013

Monoliths are functional porous materials with a three-dimensional continuous interconnected pore structure in a single piece. A monolith with uniform shape based on poly(${\gamma}$-glutamic acid) (PGA) has been prepared via a thermally induced phase separation technique using a mixture of dimethyl sulfoxide, water, and ethanol as solvent. The morphology of the obtained monolith was observed by scanning electron microscopy and the surface area of the monolith was evaluated by the Brunauer Emmett Teller method. The effects of fabrication parameters such as the concentration and molecular mass of PGA and the solvent composition have been systematically investigated. The PGA monolith was cross-linked with hexamethylene diisocyanate to produce the water-insoluble monolith. The addition of sodium chloride to the phase separation solvent affected the properties of the cross-linked monolith. The swelling ratio of the cross-linked monolith toward aqueous solutions depended on the buffer pH as well as the monolith fabrication condition. Copper(II) ion was efficiently adsorbed on the cross-linked PGA monolith, and the obtained copper-immobilized monolith showed strong antibacterial activity for Escherichia coli. By combination of the characteristic properties of PGA (e.g., high biocompatibility and biodegradability) and the unique features of monoliths (e.g., through-pore structure, large surface area, and high porosity with small pore size), the PGA monolith possesses large potentials for various industrial applications in the biomedical, environmental, analytical, and separation fields.