• Membrane Journal
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• v.13 no.4
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• pp.283-290
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• 2003

To improve membrane performance, the dead-end and Cross-flow ultrafiltration with or without ultrasound irradiation onto the membrane module were carried out using a BSA protein solution. Intermittent or continuous irradiation of ultrasound effectively suppressed the formation of fouling on membrane or removed the fouling layers from membrane. Effect of ultrasound irradiation on the enhancement of ultrafiltration performance was more increased at the operating conditions which form more membrane fouling (at the operating conditions of higher feed concentration and TMP, and lower flow rate). The permeate flukes were enhanced up to 1.9 times in case of the dead-end ultrafiltration and 1.5 times in case of the cross-flow ultrafiltration by ultrasound irradiation onto the membrane module.

• Membrane and Water Treatment
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• v.1 no.4
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• pp.253-271
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• 2010

A theoretical study for the flux enhancement by pulsation of transmembrane pressure is presented for osmotic pressure controlled ultrafiltration under laminar flow regime. The transient velocity profile is solved analytically using Green's function method. Time dependent convective diffusive equation is solved to quantify the membrane surface concentration and the permeate flux, numerically. The effects of the amplitude and frequency of pulsation on flux, surface concentration and observed retention are studied.

• Membrane and Water Treatment
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• v.2 no.2
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• pp.91-103
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• 2011

The flux behavior in the separation of equimolar bovine serum albumin (BSA) and bovine hemoglobin (HB) in aqueous solutions by cross-flow ultrafiltration (UF) was investigated, in which polyacylonitrile membrane with a molecular weight cut-off (MWCO) of 100 kDa was used. BSA and HB have comparable molar mass (67,000 vs. 68,000) but different isoelectric points (4.7 vs. 7.1). The effects of process variables including solution pH (6.5, 7.1, and 7.5), total protein concentration (1.48 and 7.40 ${\mu}M$), transmembrane pressure (69, 207, and 345 kPa), and solution ionic strength (with or without 0.01 M NaCl) on the separation were examined. It was shown that the ionic strength had a negligible effect on separation performance under the conditions studied. Although BSA and HB are not rigid bodies, the flux decline in the present cross-flow UF did not result from the mechanism of cake filtration with compression. In this regard, the specific cake resistance when pseudo steady-state was reached was evaluated and discussed.

• Membrane and Water Treatment
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• v.3 no.3
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• pp.151-168
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• 2012

Gas sparging is one of the techniques used to control the concentration polarization during ultrafiltration. In this work, the effects of gas sparging in stratified flow regime were investigated during gel layer controlling cross flow ultrafiltration in a rectangular channel. Synthetic solution of pectin was used as the gel forming solute. The liquid and gas flow rates were selected such that a stratified flow regime was prevalent in the channel. A mass transfer model was developed for this system to quantify the effects of gas flow rates on mass transfer coefficient (Sherwood number). The results were compared with the case of no gas sparging. Gas sparging led to an increase of mass transfer coefficient by about 23% in this case. The limitation of the developed model was also evaluated and it was observed that beyond a gas flow rate of 20 l/h, the model was unable to explain the experimental observation, i.e., the decrease in permeate flux with flow rate.

• Membrane Journal
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• v.9 no.1
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• pp.36-42
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• 1999

Permeation behavior of the semiconductor rinsing wastewater contammg Si particles was examined by ultrafiltration using the polyolefin tubular membrane. Flux decline with time was due to the growth of Si cake deposited on the membrane surface and the pore plugging by Si particles. Cake filtration from the cross flow application is compared to the combination of pore blocking and cake filtration from the dead-end application. The cake resistance is 3.16 x $10^{12}$ -4.34 X $\times$$10^{12}$ $m^{-1}$ for the cross flow and 6.6 x $\times$$10^{12}$ -12.19 X $\times$$10^{12}$ $\times$$m^{-1}$for the dead-end flow, respectively. At the initial stage of operation, permeation flux of cross flow type was 1.7 time higher than that of the dead end flow type. Permeation flux of cross flow was about 42 e 1m2 hr and the rejection rate of Si particles was about 96 %. The average particle size of Si particle in the permeate was 20 nm.

• Korean Membrane Journal
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• v.5 no.1
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• pp.54-60
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• 2003

The rejection properties and flux rates of silica nanoparticles in ultrafiltration membranes has been investigated. Cross-flow permeation experiments were conducted using polycarbonate track-etch flat membranes with pore sizes of 30 and 50 nm, and a silica nanoparticle solute with particle sizes of 5 and 18 nm with narrow size distributions. The fluxes and rejection factors were investigated at various particle concentrations, cross-flow velocities, pH, and ionic strengths of solution. Even though the size of the silica nanoparticles was much smaller than that of the membrane pores, the observed rejection rates were very high compared with those for a similar-sized polymer (dextran). The observed rejection rate decreased with increasing ionic strength, which implies that the transport mechanism of the silica nanoparticles is significantly influenced by electrostatic repulsion between particles and membranes.

• Korean Journal of Food Science and Technology
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• v.24 no.3
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• pp.199-203
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• 1992

This study was aimed to optimize the required condition for recovering the low soluble taste component obtained from sea tangle extract using ultrafiltration, and to investigate effects of membrane type, temperature, transmembrane pressure and flow rate respectively. We also compared relationship between the profile of permeate flux and the recovery yield of taste component under the selected optimal condition using ultrafiltration and diafiltration. Hydrophobic GR 51 PP membrane kept higher average permeate flux than hydrophilic FS membrane, and average permeate flux also had increasing tendency in relation to rising flow rate but it showed limit value of 3.7 l/min. Average permeate flux decreased as transmembrane pressure increased but it showed little change with rising temperature. Investigation upon average permeate flux, total dissolved solid and recovery yield of taste components using ultrafiltration and diafiltration resulted in relatively higher recovery yield in ultrafiltration. Compared ultrafiltration and diafiltration, average permeate flux was lower in ultrafiltration.

• Membrane Journal
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• v.8 no.2
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• pp.102-108
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• 1998

Permeation behavior of the semiconductor rinsing wastewater containing Si particles was examined by ultrafiltration using the polysulfone plate membrane. The permeation flux was gradually decreased with time. It was due to the growth of cake deposited on the membrane surface and the pore plugging by Si particles. Permeation flux of cross flow type was 1.4 times higher than that of the dead end flow type. Nitrogen back flushing which is the removing method of membrane fouling was superior to the water sweeping. With nitrogen back flushing, the decrease of permeation flux due to the fouling was recovered about 85 % to the initial flux in the flat plate membrane system. The rejection rate of Si particles was about 90 % and the size of Si particle in the permeate was about 70 nm.

• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.950-955
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• 1998

The objective of this study was to investigate the effect of running time, operating pressure, feed concentration and circulation rate on the permeation flux and the rejection rate in cross-flow ultrafiltration of polyethylene glycol(PEG) solution of molecular weight($M_w$) 8000 and 20000. The membranes used for this study were MWCO(Molecular Weight Cut-off) of 6 K and 20 K. The experiments were performed at the operating pressures of 7, 14 and 28 psi, the circulation rates of 1000 mL/min and 2000 mL/min, and the feed concentration of 100 mg/L and 1000 mg/L. At a constant pressure, the permeation flux and the observed rejection($R_o$) appeared to be approximately constant within the range of running time, 0~480 min. The permeation flux increased with increasing the operating pressure, and it increased with decreasing the feed concentration and decreasing Mw of PEG at a given pressure. On the other hand, $R_o$ decreased slightly with increasing the operating pressure. However, $R_o$ increased with increasing the feed concentration and increasing of $M_w$ of PEG at a given pressure. The variation in circulation rates did not cause any significant influence on the permeation flux. Increasing of circulation rate caused the increase of $R_o$, and $\alpha$ was increased substantially with the decrease of $M_w$ of PEG. The dimensionless parameter. permeability ratio($\alpha$), which was used to investigate flux-pressure behavior, was increased with the increase in circulation rate and operating presure. The value of $\alpha$ was less than 1 in all cases. The estimated intrinsic rejection(R). which was obtained from mass transfer coefficient, was decreased with the increase of operating pressure. However R increased with the increase of linear velocity of feed and $M_w$ of PEG.

• 수도
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• v.23 no.1_2 s.76_77
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• pp.61-70
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• 1996