• Membrane Journal
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• v.25 no.4
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• pp.367-372
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• 2015

In pressure-retarded osmosis (PRO) and forward osmosis (FO) processes, solvent (permeate) flux depends on which surface the draw solution faces. There are two operation modes. PRO mode indicates that the active layer faces the draw solution, and FO mode means that the porous substrate fronts the draw stream. It is often observed that the PRO mode produces higher flux than that of FO under the same operating conditions. The current work uses the method of proof by contradiction, and mathematically proves the intrinsic flux inequality between the two modes.

• Membrane Journal
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• v.11 no.4
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• pp.161-169
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• 2001

Single and mixed particle suspensions of kaolin, bentonite, starch and PMMA were carried out using a dead-end Amicon fi1tration cell with microfilteration membranes. The experimental data of permeate fluxes were fitted by the constant pressure fi1tration models in order to investigate fouling steps. In 0.1 wt% mixed solution of equal amount of kaolin and starch, the permeation flux was about 30% lower than the average of each particle flux. However, the permeation flux for kaolin/PMMA mixed solution was about 10% higher than the average of each particle flux. In the cases of bentonite and PMMA or starch mired solution, the improvement effect on permeation flux was weaken than that of kaolin mixed solution. Also, the membrane fouling resistance for mixed particle solution of equal amount of kaolin and starch was minimum at 0.05 wt% particle concentration.

• Journal of Korean Society on Water Environment
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• v.28 no.2
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• pp.292-299
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• 2012

The objective of this study is to develop a novel method for evaluating forward osmosis (FO) membrane performances using a non-pressurized FO system. Basic membrane performance parameters including water (A) and solute (B) permeability coefficients and unique parameter for FO membrane such as the support layer structural parameter (S) were determined in two FO modes (i.e., active layer faces feed solution (AL-FS) and active layer faces draw solution (AL-DS)). Futhermore, these parameters were compared with those determined in a pressurized reverse osmosis (RO) system. Theoretical water flux was calculated by employing these parameters to a model that accounts for the effects of both internal and external concentration polarization. Water flux from FO experiment was compared to theoretical water fluxes for assessing the reliability of those parameters determined in three different operation modes (i.e., AL-FS FO, AL-DS FO, and RO modes). It is demonstrated that FO membrane performance parameters can be accurately measured in non-pressurized FO mode. Specifically, membrane performance parameters determined in AL-DS FO mode most accurately predict FO water flux. This implies that the evaluation of FO membrane performances should be performed in non-pressurized FO mode, which can prevent membrane compaction and/or defect and more precisely reflect FO operation conditions.

• Membrane and Water Treatment
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• v.7 no.2
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• pp.155-173
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• 2016

The present work has been focused on the development of polysulfone (PSf) ultrafiltration membrane via blending by sulfonated polyethersulfone (SPES) in order to permeability enhancement for ultrafiltration of cheese whey. In this regards, sulfonation of polyethersulfone was carried out and the degree of sulfonation was estimated. The effect of blend ratio on morphology, porosity, permeation and fouling of PSf / SPES membranes was investigated. Filtration experiments of whey were conducted for separation of macromolecules and proteins from the lactose enrichment phase. The morphology and performance of membranes were evaluated using different techniques such SEM, AFM, and contact angle measurements. The contact angle measurement showed that the hydrophilicity of membrane was increased by adding SPES. According to AFM images, PSf / SPES membranes exhibited lower roughness compared to neat PSf membrane. The water and whey flux of these membranes were higher than neat membrane. However, flux was decreased when the PSf / SPES blend ratio was 0/100. It can be attributed to pore size and morphology changes. Further, fouling parameters of PSf membrane were improved after blending. The blend membranes show a great potential to be used practically in proteins separation from cheese whey.

• Membrane and Water Treatment
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• v.8 no.6
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• pp.575-590
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• 2017

PolyHIPEs membrane prepared with styrene (St), divinylbenzene (DVB), and ethylhexyl acrylate (EHA) can yield a unique pore structure provided by large voids highly interconnected by many small window throats. With the advantageous pore structure, PolyHIPE presents a potential as a support for carrier facilitated transport membrane. Tricaprylmethylammonium chloride (Aliquat 336) can be efficiently incorporated into the PolyHIPE membrane by a two-step solvent-nonsolvent method to obtain an Aliquat 336-immobilized PolyHIPE membrane with good stability. The study of Cr (VI) transport through Aliquat 336-immobilized PolyHIPE membrane indicates that the membrane has high initial flux and maxima stripping flux ($J_f^o=15.01({\mu}mol/m^2s)$, $J_s^{max}=6.15({\mu}mol/m^2s)$). The reusability study shows that the Aliquat 336-immobilized PolyHIPE membrane can maintain high Cr(VI) recovery efficiency even after 15 cycles of operations. The developed membrane was also used in the separation of Cr (VI) from other anions (i.e., $SO_4{^{2-}}$ and $NO_3{^-}$) and other cations (i.e., Ni (II), Mg (II) and Cu (II)) with good selectivity.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.2
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• pp.207-215
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• 2006

This study evaluated the effect of ultrasonic irradiation on reducing membrane fouling for the treatment of chemically treated leachate and biologically treated leachate. The experiments on improvement of membrane flux according to the membrane types(MF and UF) and membrane materials were performed with changing frequency(40 kHz and 120 kHz) and intensity(200 W and 400 W) of ultrasound in ultrasonic membrane separation apparatus which ultrasound can be periodically irradiated. Additionally, the effect of dual frequency ultrasound which 40 kHz md 120 kHz are irradiated simultaneously was evaluated. The improvement of membrane flux by periodical ultrasound irradiation was higher in microfiltration(MF) membrane than in ultrafiltration(UF) membrane. It was sustained more in the MF membrane of polyvinylidene fluoride(PVDF) than in that of polysulfon(PS). Ultrasonic improvement of membrane flux was different depending on the characteristics of target wastewater. It was sustainably maintained without reclogging using dual frequency ultrasound although the improvement of membrane flux was lower.

• Proceedings of the Membrane Society of Korea Conference
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• 2000.04a
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• pp.113-116
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• 2000

• Journal of Korean Society of Environmental Engineers
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• v.39 no.8
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• pp.456-461
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• 2017

In this study, nano fibers with various physical properties were materialized by using a variety of polymers [PAN (Polyacrylonitrile), PU (Polyuretane), PSU (Polysulfone)] which are raw materials of dope solution manufactured for electrospinning and solvents [NMP (N-methyl-2 pyrrolidone), DMF (Dimethylformamide)] and evaluated characteristics of their flux and SS (Suspended Solids) separation and then ascertained application of manufactured fibers as separation membrane for water treatment. In this study, analysis of surface of manufactured material was carried out through SEM analysis to ascertain the cause of flux and SS separation performance by checking diameter, uniformity and straightness of fiber. If additive is used in manufacturing nano fiber water treatment separation membrane, it is expected to solve problems such as membrane fouling and mechanical strength and to be used as basic factor for manufacturing separation membrane with catalyst function added.

• Korean Membrane Journal
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• v.2 no.1
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• pp.36-47
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• 2000

This paper deals with the separation of MTBE-methanol mixtures using crosslinked Poly(vinyl alcohol)(PVA) membranes with sulfur-succinic acid(SSA) as a crosslinking agent by pervaporation and vapor permeation technique. The operating temperatures, methanol concentration in feed mixtures, and SSA concentrations in PVA membranes were varied to investigate the separation performance of PVA/SSA membranes and the optimum separation characteristics by pervaporation and vapor permeation. And also, for PVA/SSA membranes, the swelling measurements were carried out to study the transport phenomena. The swelling measurements were carried out for pure MTBE and methanol, and MTBE/methanol=90/10, 80/20 mixtures using PVA/SSA membranes with varying SSA compositions. There are two factors of the membrane network and the hydrogen bonding. In pervaporation separation was also carried out for MTBE/methanol=90/10, 80/20 mixtures at various temperatures. The sulfuric acid group in SSA took an important role in the membrane performance. The crosslinking effect might be over the hydrogen bonding effect due to the sulfuric acid group at 3 and 5% SSA membranes, and this two factors act vice versa on 7% SSA membrane. In this case, the 5% SSA membrane shows the highest separation factor of 2,095 with the flux of 12.79g/㎡$.$hr for MTBE/methanol=80/20 mixtures at 30$^{\circ}C$ which this mixtures show near the azeotopic composition. Compared to pervaporation, vapor permeation showed less flux and similar separation factor. In this case, the flux decreased significantly because of compact structure and the effect of hydrogen bonding. In vapor permeation, density or concentration of methanol in vaporous feed is lower than that of methanol in liquid feed, as a result, the hydrogen bonding portion between the solvent and the hydroxyl group in PVA is reduced in vapor permeation. In this case, the 7% SSA membranes shows the highest separation factor of 2,187 with the flux of 4.84g/㎡$.$hr for MTBE/methanol=80/20 mixtures at 30$^{\circ}C$.

• Membrane Journal
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• v.6 no.4
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• pp.203-212
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• 1996

The operating parameters influencing on limiting flux was investigated in the ultrafiltration of PVA, and a new model, which is based on the Amiar model using the concept of heat transfer coefficient, was devised to overcome the limitation of gel-layer model. Using polysulfone plate-unit membrane (MWCO=20,000) and hollow-fiber membrane (MWCO= 30,000), ultrafiltration characteristics of PVA was examined with the variation of operating parameters such as cross flow velocity, transmembrane pressure, temperature, and PVA concentration. According to experimental results, the ultrafiltration of PVA through polysulfone membrane is mainly controlled by well-known phenomena of concentration polarization caused by gel-layer formation. On the contrary, in hollow fiber membrane was observed upward limiting flux which can not be explained by gel-layer model. New model was applied to predict the upward limiting flux behavior with partial satisfaction. The application of new model including viscosity correction factor, however, revealed that PVA ultrafiltration is closely related to the viscosity of permeating fluid.