• Journal of Environmental Science International
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• v.1 no.2
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• pp.93.1-104
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• 1992

Because of varied functions and characteristics, water soluble polymers have lone attracted much intrest in both academic and industrial fields, especially now in pollution problems such as wastewater treatment through ployrneric flocculants. In this regard, the main objective of this study is to synthesize polymeric floccuants containning hydrophobic group in presence of the potassium persulfate/sodium thiosulfate redox system and to estimate their flocculating ability on the kaolin suspension. In order to test the flocculating power of flocculant prepared on the kaolin suspension system, turbidity of the supernatant liquid, residence time, filtration rate of flocculated samples, have additionally been measured from the flocculation experiments and analysed In comparision with the theoretical background.

• YAKHAK HOEJI
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• v.35 no.6
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• pp.461-465
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• 1991

Silica-based gel filtration chromatography has been used to characterize molecular weight of proteins. However, the molecular weight measured by this method was distorted by protein-silica interactions like hydrophobic and electrostatic forces. Therefore, we characterized protein-silica interaction using two forms of phytochrome (124 kDa) having different hydrophobicity and surface charge. PH and ionic strength affected the retention time of phytochrome suggesting that electrostatic force is the major interaction between protein and silica surface.

• Membrane and Water Treatment
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• v.15 no.1
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• pp.31-39
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• 2024

The flow in a nanopore of filtration membrane is often multiscale and consists of both the adsorbed layer flow and the intermediate continuum fluid flow. There is a controversy on which interface the slippage should occur in the nanopore filtration: On the adsorbed layer-pore wall interface or on the adsorbed layer-continuum fluid interface? What is the difference between these two slippage effects? We address these subjects in the present study by using the multiscale flow equations incorporating the slippage on different interfaces. Based on the limiting shear strength model for the slippage, it was found from the calculation results that for the hydrophobic pore wall the slippage surely occurs on the adsorbed layer-pore wall interface, however for the hydrophilic pore wall, the slippage can occur on either of the two interfaces, dependent on the competition between the interfacial shear strength on the adsorbed layer-pore wall interface and that on the adsorbed layer-continuum fluid interface. Since the slippage on the adsorbed layer-pore wall interface can be designed while that on the adsorbed layer-continuum fluid interface can not, the former slippage can result in the flux through the nanopore much higher than the latter slippage by designing a highly hydrophobic pore wall surface. The obtained results are of significant interest to the design and application of the interfacial slippage in nanoporous filtration membranes for both improving the flux and conserving the energy cost.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.236-236
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• 2012

In this study, we present the salt repellent behavior of superhydrophobic filtration membrane. Bio-fouling or mineral-fouling is the main factor of decreasing the performance of filtration membrane. The superhydrophobic modification of filtration membrane using PECVD (Plasma enhanced chemical vapor deposition) is introduced. The oxygen plasma was introduced for developing nano hairy structures and subsequent HMDSO (Hexamethyldisiloxane) coating was used for enhancing low surface energy. Saline water evaporation test was carried out to evaluate the difference of contamination of salt on superhydrophobic and moderately hydrophobic filtration membrane. EDS and EPMA were used for visualizing the residue of salt crystal.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1398-1402
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• 2005

Riverbank filtration is a natural process using alluvial aquifers to remove contaminants and pathogens in river water for the production of drinking water. In riverbank filtration, the understanding of contaminant transport is an important task for the production of high quality drinking water. This study investigates the transport behavior of hydrophobic organic contaminants when colloids (dissolved organic matter and bacteria) are present in the aquifer. A mathematical model for the transport of contaminants is developed and solved numerically for various situations. Results show that in the riverbank filtration the presence of DOM and bacteria enhances the mobility of contaminant significantly. Sensitivity analysis indicates that the distribution of the total aqueous Phase contaminant is significantly affected by distribution coefficients which account for affinity of solid or colloidal Phase to contaminant.

• Journal of the East Asian Society of Dietary Life
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• v.4 no.3
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• pp.59-65
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• 1994

Growth-stimulating effects of cow's milk was examined using Vero cell cultre. Medium containing whole cow's milk stimulated cell growth about the same degree as that containing fetal bovine serum. The growth-stimulating factor in cow's milk was purified using hydrophobic (phenyl-sepharose) and gel filtration (Sephadex G-100) column chromatographies. It appeared that the factor is a highly hydrophobic protein, since the major growth-stimulating activity was found in the fractions eluted with 50% ethylene glycol from the phenyl-sepharose column during the purification. The purified factor showed a single band on the polyacrylamide gel electrophoresis in the presence of 1% (w/v) SDS. The factor has been found to have a relatively high molecular weight in the range of about Mr=100,000-150,000. In the presence of the purified factor (5%, w/v) in the culture medium, the incorporation of [3H]-thymidine into the cells was increased approximately 2,400-fold over that in the presence of 5% (w/v) fetal bovine serum. It seems that the growth-stimulating factor purified in this study is one of the major growth factors in the cow's milk.

• Korean Membrane Journal
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• v.1 no.1
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• pp.43-49
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• 1999

Separation of soluble oil was investigated during filtration of cutting oil emulsion using various commercial ultrafiltration membranes. The surface properties of membranes used were hydrophilic hydrophobic and modified surfaces by various surfactant pretreatments. Conditions varied include stirring speed transmeembrane pressure membrane type and surfactant type for pretreatment. The results give some indication of mechanisms occurring at the membrane surface. Surfactant pretreatments significantly improved water flux and UF flux of hydrophilic regenerated cellulose(up to 2.4x for YM100) and hydrophobic polysulfone (up to 2.2x for PTHK) membranes depending on surfactant type and operating conditions. The UF flux enhancement was attributed to membrane swelling and reduction of interfacial surface tension between oil droplets and membrane surface. unexpectedly the hydrophilic membranes revealed greater flux enhancement than the hydrophobic membranes. The results also showed a greater improvement in UF flux at lower operating pressure.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1986.12a
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• pp.515.1-515
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• 1986

Thermostable tryptophanase was extracted from a thermophilie bacterium, strain T which was absolutely symbiotic with strain 5. The enzyme was purified 14.7 fold with 5.8% yield by chromatographies using ion exchange, gel filtration, and hydrophobic interaction columns, followed by high performance liquid chromatography on hydroxyapatite column. The purified enzyme has a molecular weight of approximately 210,000 estimated by gel filtration column chromatography, and the molecular weight of subunit was determined by SDS polyacrylamide gel electrophoresis to be 46,000, which indicates that the native enzyme is made of four homologous subunits. The tryptophanase was stable at 65o0 and the optimum temperature for the enzyme activity for 20 min reaction was 70$^{\circ}C$. The purified enzyme activity for 20 min ieaction was 70$^{\circ}C$. The purified enzyme catalyzed the degradation of L-tryptophan into indole, pyruvate and ammonia in the presence of pyridoxal phosphate. 5-Hydroxy-Ltryptophan, 5-methyl-DL-tryptophan, L-cysteine, S-methyl-L-cysteine, 5-methyl-DL-tryptophan, L-cysteine, S-methyl-Lcysteine, and L-serine were also used as substrates to form pyruvate. The amino acid composition of the tryptophanase was determined, and found to contain a high percentage of hydrophobic amino acids, especially in the proline content, which was much higher than that of Escherichia coli tryptophanase. In addition, the 35N-terminal amino acid sequence of the tryptophanase was completely different from that of E. coli tryptophanase.

• Journal of Environmental Science International
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• v.23 no.9
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• pp.1655-1662
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• 2014

A comprehensive fractionation technique was applied to a set of water samples obtained along drinking water treatment process with ozonation and biological activated carbon (BAC) process to obtain detailed profiles of dissolved organic matter (DOM) and to evaluate the haloacetic acid (HAA) formation potentials of these DOM fractions. The results indicated that coagulation-sedimentation-sand filtration treatment showed limited ability to remove hydrophilic fraction (28%), while removal of hydrophobic and transphilic fraction were 57% and 40%, respectively. And ozonation and BAC treatment showed limited ability to remove hydrophobic fractions (6%), while removal of hydrophilic and transphilic fractions were 25% and 18%. The haloacetic acid formation potential (HAAFP)/dissolved organic carbon (DOC) of hydrophilic fraction was the highest along the treatment train and HAAFP/DOC of hydrophilic fraction was higher than hydrophobic and transphilic fraction as 23%~30%, because of better removal for hydrophobic fraction both in concentration and reactivity.

• Microbiology and Biotechnology Letters
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• v.20 no.1
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• pp.25-33
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• 1992

One acetolactate synthase isozyme which has Rf value of 0.83 on polyacrylamide gel electrophoresis was purified from Sewatia marcescens ATCC 25419 by ammonium sulfate fractionation, DEAE-Sephacel chromatography, Phenyl-Sepharose chromatography, Sephacryt S-400 gel filtration followed by native gel elution. The native molecular weight of the enzyme was determined to be 531,400 by gel filtration method, and SDS-polyacrylamide gel electrophoresis separated the native enzyme into two polypeptides having molecular sizes of 55,000 and 38,900 respectively. In kinetic parameters, $K_m$ value for pyruvate was 2.54 mM, and $V_{max}$ was 21.75 nmoie/min/mg. The enzyme showed maximal activity around pH 8.0 and optimal temperature of the acetolactate formation was $37^{\circ}C$. Feedback inhibition studies indicate that the purified enzyme is rather resistant to branched chain amino acids when compared with acetolactate synthase isozymes of plants or other enterobacteria.