• Applied Chemistry for Engineering
• /
• v.7 no.5
• /
• pp.977-984
• /
• 1996

Liquid-liquid extractions by use of hollow fiber membrane module are fast because of the large surface area per volume. In these membranes, the extractant and feed can be contacted at high speed and two flows are completely independent, so there are no problems with loading and channeling. In this paper, it was investigated the selectivities of extractants for extraction of heavy metals from aqueous solution into organic extractants by using the hollow fiber membrane. To identify the effect of distribution ratio on mass transfer in the membrane, we also compared the distribution ratio with mass transfer coefficient. From these experiments for the system with high distribution ratio, effect of the distribution ratio on mass transfer was weak compare with the low distribution ratio system in the hollow fiber membrane.

• Membrane Journal
• /
• v.6 no.2
• /
• pp.96-100
• /
• 1996

In order to improve the permeability of the homogenous membrane of poly(carbobenzoxy-L-lysin)(PCLL), which has very high selectivity of helium gas to nitrogen gas, asymmetric porous membranes of PCLL were prepared by casting from 20% solutions in dioxane and dimethylformamide(DMF), respectively. The membranes were characterized by measuring the number of the pores, the pore size distribution of the surface(the skin layer) and the thickness of the skin layer by scanning electron microscope and transmission electron microscope. The mean pore size and the pore density were lower for the membrane cast from dioxane than that from DMF, which was explained by the mechanism of the formation of the pores in the asymmetric porous membrane. The permeability coefficient observed could be roughly explained by the viscous flow through the skin layer. However, the selectivity observed was against the theory of the viscous flow.

• Membrane Journal
• /
• v.26 no.4
• /
• pp.266-272
• /
• 2016

The separation and purification of lysozyme enzyme from chicken egg white (CEW) solution was studied using the dead-end filtration. The optimum operation conditions of the dead-end filtration reveal that the maximum value of permselectivity of lysozyme to the other proteins of ovalbumin and conalbumin in the CEW solution was tested with change of molecular weight cut-off (MWCO) of ultrafitration membrane and pH of the CEW solution. The optimum operation conditions for the efficient permeable separation of lysozyme from the CEW solution are that the membrane MWCO is 30 kD and the pH of CEW solution is 11. At this optimum operation conditions, the maximum value of permselectivity of lysozyme to total proteins in CEW solution is about 83.

• Membrane Journal
• /
• v.25 no.1
• /
• pp.1-6
• /
• 2015

It was known that the polarlized surface of silver nanoparticles could be interacted revesibly with olefin molecules for facilitated olefin transport. However, it was thought that it can be regenerated by interaction between oxide surface of AgNPs and olefin molecules because the surface of the silver nanoparticles is easily oxidized in the air. In order to investigate the effect of the silver oxide, 5 wt% AgO or $Ag_2O$ was dispersed in polymer PVP solutions and 0.005~0.02% electron acceptor as TCNQ or p-BQ were added to fabricate the separation membrane. After the addition of the electron acceptor, it was expected to improve the polarity on the surface of the silver oxide and the degree of dispersion. The characteristics of the separation membrane were identified by the gas permeance, XPS and TEM.

• Journal of the Korean Electrochemical Society
• /
• v.12 no.4
• /
• pp.335-341
• /
• 2009

Organic-inorganic hybrid sol-gel matrices were used as hosts for chloro (5, 10, 15, 20-tetraphenylporphyrinato) cobalt (III) (Co[TPP]Cl), a known ionophore for nitrite. The sol-gel precursor was prepared by the reaction of (3-isocyanopropyl) triethoxysilane with 1,4-butanediol. An appropriate amount of the anion-exchanger, tridodecylmethylammonium chloride (TDMAC) and the plasticizer, tributylphosphate (DBP) were used as membrane additives. On mixing with an acidic catalyst, the sol-state precursors slowly gelled, yielding a membrane in which the active components, Co[TPP]Cl and TDMAC, were encapsulated. The performances of the sol-gel membrane-based electrodes were compared to those of Co[TPP]Cl-based poly(vinyl chloride) (PVC) membrane electrodes. Membranes with a molar ratio of Co[TPP]Cl: TDMAC (1 : 0.1) showed reasonable response slopes toward nitrite. The response slopes were typically 53 mV/decade between $10^{-5.4}$ and $10^{-1.0}\;M$. Selectivities toward nitrite over hydrophilic and small anions such as chloride were somewhat inferior to those observed with PVC-based membranes, but selectivities over lipophilic anions were quite similar. Reduced asymmetry potentials due to protein adsorption were found to occur with the sol-gel matrix relative to PVC-based films when the sensors were employed as a detector in flow-through configuration.

• Applied Chemistry for Engineering
• /
• v.10 no.4
• /
• pp.515-522
• /
• 1999

Asymmetric polyetherimide membrane were prepared by phase inversion method, and the effects of NaOH concentration and reaction time on the morphology change of the polyetherimide membranes were studied. The morphology of skin layers varied from dense structure to sphere structure with increasing concentration of modification solution. The thickness of dense layer increased with increasing reaction time. However, when either the concentration of modifying solution was very high or the reaction time was very long, the dense layers of the asymmetric membrane were disappeared. From these results, it was found that the surface morphology of the asymmetric polyetherimide membranes depended strongly on the modification conditions such as concentration of modification solution and reaction time. These results might be explained by the hydrolysis reaction of polyetherimide into polyamic acid by the NaOH solution.

• Applied Chemistry for Engineering
• /
• v.10 no.4
• /
• pp.502-508
• /
• 1999

We prepared non-porous membrane on the $Al_2O_3$ substrate with the different pore by the size by the plasma polymerization of $CHF_3$. We studied the permeability characteristics of membrane by Ar treatment and the effect of substrate pore size on gas permeation mechanism. The selectivity was increased with Ar plasma treatment time and rf-power near the substrate to the cathode while the permeability was decreased. It was observed that the solution-diffusion model would be applied to non-porous layers while it is applied Knudsen diffusion model to the substrate. From the experimental observation, it could be concluded that the pore size of $Al_2O_3$ membrane influenced on the permeability and the selectivity.

• Applied Chemistry for Engineering
• /
• v.1 no.2
• /
• pp.140-146
• /
• 1990

Polydimethylsiloxane(PDMS) containing [N, N'-bis (3- (salicylidene amino) propyl) amine Co(II)] (Co(saldpt)) as a fixed oxygen carrier was synthesized. UV-visible spectra of the membrane demonstrated that Co(saldpt) binded molecular oxygen specificaaly and reversibly. From time lag method experiment, it was found that both oxygen permeability and diffusibity increase with decreasing upstream pressure, while solubility maintain nearly constant. The maximum oxygen permeability and oxygen selectivity over nitrogen obtained was 18.6 barrer and 4, respectively, at 25 mmHg and $40^{\circ}C$ from the the PDMS membrane containing 1 wt% of Co(saldpt). Facilitation behavior was explained in terms of the dual sorption model.

• Membrane Journal
• /
• v.22 no.5
• /
• pp.309-317
• /
• 2012

In this study, PTMSP/LDH composite membranes were prepared by the solution intercalation method with 1, 3, and 5 wt% LDH contents to PTMSP. To investigate the physico-chemical characteristics of composite membranes, the analytical methods such as FT-IR, TGA, XRD, UTM, and SEM have been utilized, and the gas permeability and selectivity properties of $H_2$, $N_2$, and $CO_2$ were evaluated. The permeability of the PTMSP/LDH composite membranes decreased as LDH content increased and the selectivity $H_2$ and $CO_2$ showed the maximum value at 5 wt% of LDH content. Permeability of PTMSP/LDH composite membrane increased as the gas permeation pressure increased. The difference of the increase in gas permeation pressure of the permeability of PTMSP/LDH composite membrane was slightly smaller than of PTMSP membrane.

• Korean Chemical Engineering Research
• /
• v.56 no.1
• /
• pp.29-41
• /
• 2018

Separating a mixture having an azeotrope or low relative volatility with single distillation column is difficult. Separating water-acetic acid mixture and water-ethanol mixture with a distillation column consumes a lot of energy. Pervaporation membrane can be used to separate the mixture in the concentration region where separation is difficult with distillation. We simulated a distillation-membrane hybrid process where membrane is located on the head of the distillation column for efficient separation of water-acetic acid and water-ethanol mixture. Permeability data were obtained from experiments and literature. We formulated an optimization problem for the process with total annual cost (TAC) as an objective function and major design variables as optimization variables. Major optimization variable affecting TAC of the hybrid process was shown to be distillate concentration. We also suggested a simplified optimization procedure to get a close-to-optimal solution.