• Journal of the Korean institute of surface engineering
• /
• v.51 no.5
• /
• pp.277-290
• /
• 2018

In this study, Pd-Ni-Ag alloy hydrogen separation membranes were fabricated by Pd/Ag/Pd/Ni/Pd multi-layer sputter deposition on the modified MIM(Metal Injection Molding)-PSS(Porous Stainless Steel) support and followed heat treatment. Nickel, used as an alloying element in Pd alloy membranes, is inexpensive and stable material in a hydrogen isotope environment at high temperature up to 1123 K. Hydrogen perm-selectivity of Pd-Ni-Ag alloy membranes is affected not only by composition of membrane films but also by other factors such as surface properties of PSS support, microstructure of membrane films and inter-diffused impurities from PSS support. In order to clarify the effect of surface Ni composition on hydrogen perm-selectivity of Pd-Ni-Ag alloy membranes, the other effects were significantly minimized by the formation of dense and homogeneous Pd-Ni-Ag alloy membranes. Hydrogen permeation test showed that hydrogen permeability decreased from $7.6{\times}10^{-09}$ to $1.02{\times}10^{-09}mol/m{\cdot}s{\cdot}Pa^{0.5}$ as Ni composition increased from 0 to 16 wt% and the selectivity for $H_2/N_2$ was infinite.

• Membrane Journal
• /
• v.29 no.4
• /
• pp.216-222
• /
• 2019

In this study, permeation experiments were conducted using naturally circulating spherical beads, backwashable plate membrane and the air supplied from the bottom of the MBR. The activated sludge solution was maintained at 8,000 mg/L of MLSS and compared transmembrane pressure (TMP) with respect to FR (filtration and relaxation), FR/BW (filtration and relaxation/backwashing), SFCO (sinusoidal filtration continuous operation) and SFCO/BW (sinusoidal filtration continuous operation/backwashing). As the backwashing flux decreased from 47 to $14L/m^2{\cdot}hr$, the TMP increased generally, but the TMP of FR system increased significantly comparing with SFCO. In addition, the backwashing method reduced more TMP comparing to the cleaning method using spherical beads, and it was confirmed that the operation method using the spherical beads and the backwashing simultaneously is more effective than each method.

• Membrane and Water Treatment
• /
• v.14 no.2
• /
• pp.85-93
• /
• 2023

Membrane separation is widely used for several applications such as water treatment, membrane reactors and climate change. Cross-linked organic-inorganic hybrid polyvinylidene fluoride (PVDF) / Tetraethyl orthosilicate (TEOS) was adopted for the preparation of optimized hollow membrane (HFM) for membrane distillation or other low pressure separators for mechanical properties and permeability under varying pretreatment schemes. HFMs were prepared on semi-pilot membrane fabrication system. Novel adopted post-treatment schemes involved soaking in glycerol, magnesium sulphate (MgSO₄), sodium hypochlorite (NaOCl), and isopropanol for different durations. All fibers were characterized for morphology using a scanning electron microscope (SEM), surface roughness using atomic force microscope (AFM), elemental composition by examining Energy Dispersive Spectroscopy (EDS), water contact angle (CA°) and porosity. The performance of the fibers was evaluated for pure water permeation flux (PWF). Post-treatment with MgSO₄ gave the highest both tensile modulus and flux. Assessment of properties and performance revealed comparable results with other organic-inorganic separators, HF or flat. In spite of few reported data on post treatment using MgSO₄ in presence of TEOS, this proves the potential of low cost treatment without negative impact on other membrane properties. The flux is also comparable with hypochlorite which manifests substantial precaution requirements in actual industrial use.The relatively high values of flux/bar for sample treated with TEOS, post treated with MgSO₄ and hypochlorite are 88 and 82 LMH/bar respectively.

• Korean Journal of Food Science and Technology
• /
• v.35 no.1
• /
• pp.67-71
• /
• 2003

Alginates were irradiated in an aqueous solution with $Co^{60}$ gamma rays in the dose ranges from 0 to 100 kGy, and investigated the relationship between the intrinsic viscosity $([{\eta}])$ and the molecular weight $(M_w)$ of alginates. The molecular weight of alginate was measured by gel permeation chromatography and the ranges from 1,894 to 135,174 Da were obtained. The molecular weight of alginate decreased markedly with increasing the degree of ${\gamma}-ray$ dose rate. The intrinsic viscosity of alginate solution after ${\gamma}-irradiation$ showed the ranges from 9.83 (g/g) to 602.69 (g/g), depending upon the ${\gamma}-irradiation$ dose. The molecular weight of alginate dependence of the intrinsic viscosity of the alginate solution would be expressed by Mark-Houwink equation. With a linearization of molecular weight and the intrinsic viscosity of the alginate solution, Mark-Houwink equation could be expressed with constant variables and the real data fitted to the equation of $[{\eta}]=2.2{\times}10^{-6}\;{M_w}^{1.656}\;(R^2=0.998)$.

• YAKHAK HOEJI
• /
• v.42 no.1
• /
• pp.25-30
• /
• 1998

This study was designed to compare the absorption fraction and extent of ketoprofen gels and a matrix typed ketoprofen plaster patch. 3g (90mg as ketoprofen) of the two gels whi ch has oleohydrogel or hydrogel as a base, respectively, and 3 pieces of plaster patches (90mg as ketoprofen) were, applied in the area of 210$cm^2$ on forearm in 12 volunteers by cross over design. Blood samples were collected serially up to 24 hours and the plasma concentrations of ketoprofen were analyzed by HPLC using flurbiprofen as an internal standard. The detection limit of the assay was 1ng/ml of ketoprofen in plasma. The pharmacokinetic parameters (e.g. $AUC_{24hr}$, $AUMC_{24hr}$, MRT, Fraction Absorbed) were calculated from the plasma concentrations time data of each volunteer. The oleo-hydrogel showed significantly higher absorption fraction and extent of ketoprofen than the current hydrogel. The mean plasma concentrations of the oleo-hydrogel were increased to 98.46${\pm}$23.15ng/ml by 6 hour after application, and increased futher to 100.61${\pm}$18.65ng/ml at 24 hour. On the other hand, those of the hydrogel were increased 17.61${\pm}$18.65ng/ml at 5 hour to 34.68${\pm}$9.65ng/ml at 24 hour gradually. Therefore the plasma concentrations of oleo-hydrogel at each measured time were 3~7 times greater than those of the hydrogel with statistical significance. The $AUC_{24hr}$ (1797.26${\pm}$52.09ng.h/ml) of the oleo-hydrogel was 3.5 times greater (P<0.05) than that (516.17${\pm}$104.52ng.h/ml) of the hydrogel. The plaster patches showed higher bioavailability ($AUC_{24hr}$ 2877.37${\pm}$578.27ng.h/ml) than the olea-hydrogel ($AUC_{24hr}$ 1797.26${\pm}$52.09ng.h/ml) without statistical significance. But the absorption fraction of the oleo-hydrogel was rather higher than that of the plaster patches during the first 6 hours after administration. These results suggest that newly developed ketoprofen gel which is used oleo-hydrogel as a base would show excellent skin permeation on topical application for the corresponding clinical indications and could be absorbed as well as plaster patches.

• Korean Journal of Food Science and Technology
• /
• v.29 no.3
• /
• pp.417-426
• /
• 1997

Rice bran protein hydrolysates were prepared and some of their physicochemical properties were investigated to utilize rice bran as starting material for functional food ingredient. Rice bran proteins (RBP) were prepared from defatted rice bran by alkaline extraction and isoelectric precipitation. The enzyme for hydrolysis of RBP was selected through measuring relative activity by pH-drop method and comparing the degree of hydrolysis (DH) of hydrolysates. The enzymatic hydrolysates prepared by $Esperase^{\circledR}$ treatment were partitioned into two fractions by ultrafiltration(UF) with a 10 kDa molecular weight cut-off membrane. Each fraction was applied to a cholic acid-conjugated ${\omega}-aminohexyl$ Sepharose 4B column and the bile acid-binding components were obtained by eluting with deoxycholate. Gel permeation chromatography on a Sephadex G-50 column revealed that molecular weight of the bile acid-binding fraction of UF permeate was distributed in ranges of $2\;kDa{\sim}10\;kDa$ and $0.2\;kDa{\sim}0.6\;kDa$. Three peaks (R-1, R-2 and R-3) were obtained by prep-HPLC of bile acid-binding fraction of UF retentate and analyzed for total and free amino acid composition. The results showed that proline content of the bile-acid binding polypeptides and peptides was four times as much as that of rice bran protein and that the peak corresponding to higher average hydrophobicity had a higher free amino acid content. Average hydrophobicity slightly increased with enzymatic hydrolysis.

• Korean Journal of Microbiology
• /
• v.32 no.4
• /
• pp.315-321
• /
• 1994

Glyoxalase I was purified 2,294-fold from Pleurotus ostreatus by S-hexylglutathione affinity chromatography, Sephadex G-150 gel filtration chromatography and DEAE-sepharose A-50 CL-6B ion exchange chromatography with an overall yield of 21.7%. The molecular mass determined by gel filtration was found to be approx. 34 kDa. SDS-PAGE revealed that the enzyme consists of two identical subunits with a molecular mass of approx. 17 kDa. The K sub(m) values of this enzyme for methylglyoxal and phenylglyoxal were 0.39 mM and 0.22 mM, respectively. And this enzyme had a strong affinity for L-xylosone and hydroxypyruvaldehyde. The enzyme showed its optimal activity at pH 6.5-7.5 and at $40^{\circ}C$. $^1H$-NMR spectroscopic analysis of enzymic reaction showed that this enzyme catalyzes intramolecular proton transfer.

• Polymer(Korea)
• /
• v.33 no.2
• /
• pp.158-163
• /
• 2009

In this study, we synthesized a series of dendritic polystyrene-b-linear poly (t-butyl acrylate) copolymers with well-defined molecular architectures. The hydroxyl group located at the focal point of the second generation dendron bearing polystyrene ($M_n$ = 1000 g/mol) peripheries was converted into amine group via the following stepwise reactions: 1) tosylatoin, 2) azidation, and 3) reduction. On the other hand, the linear poly (t-butyl acrylate)s were prepared by an atom transfer radical polymerization (ATRP) of t-butyl acrylate where benzyl 2-bromopropanoate and Cu(I)Br/PMDETA were used as initiator and catalyst, respectively. To convert the end group of prepared poly (t-butyl acrylate) s into carboxylic acid, a debenzylation was performed using Pd/C catalyst under $H_2$ atmosphere. In the final step, dendritic-linear block copolymers were obtained through a simple amide coupling reaction mediated by 4-(dimethylamino) pyridine(DMAP) and N,N'-diisopropylcarbodiimide(DIPC). The resulting diblock copolymers were shown to have well-defined molecular weights and narrow molecular weight distributions as supported by $^1H$-NMR spectroscopy and gel permeation chromatography(GPC).

• KSBB Journal
• /
• v.15 no.2
• /
• pp.167-173
• /
• 2000

For selective elimination of salt from boiled oyster extract (BOE), electrodialyzer was used and the desalination conditions of B BOE were investigated. The ion-exchange membrane with a molecular weight cut off 100 Da was used for desalting of B BOE. The desalination efficiency at pH 4.0 was 13% higher than that at pH 9.0 when BOE was desalted for 90min. The e electrodialysis pro$\infty$ss could remove above 90% of the initial salt content when 5% BOE was desalted at pH 5.62 for 1 100min. The initial volume and concentration of permeation solution did not have significant effects on desalination time and r ratio. The important factors for the desalination of BOE were found to be pH and concentration of BOE. The results obtained prove that electrodialysis is a practical solution to the problem of selective elimination of salt from BOE.

• Applied Chemistry for Engineering
• /
• v.8 no.5
• /
• pp.763-770
• /
• 1997

The separation of benzene-cyclohexane mixture using (O/W)/O emulsion liquid membrane was studied. The operating parameters which can affect the selectivity, benzene yield, and emulsion size distribution were examined and determined by the batch type operation. The unsteady state and steady state extraction behavior in continuous pulse stirred reactor(CPSR) were verified. The optimum conditions for benzene selectivity and yield in batch operation were as follows; emulsion mixing intensity 4000 rpm, Tween 80 concentration 0.4%, volume ratio of membrane phase to internal phase 0.75, volume ratio of dispersed phase to continuous phase 0.5, and permeation time 10 minutes, As impeller speed increased and the microdrop holdup decreased, the Sauter mean diameter decreased. Turbulence damping parameter of modified Calabrease correlation considering microdrop holdup was 2.28. The optimum conditions of continuous operation were as follows; agitation speed 300 rpm, pulse frequence 2 times/sec, flow rate of continuous phase 30ml/min, and flow rate of emulsion phase 12.0ml/min.