• Journal of Korean Society for Atmospheric Environment
• /
• v.9 no.1
• /
• pp.101-106
• /
• 1993

In order to separate the Freon-12 and air mixture$(CF_2Cl_2/Air=0.1/99.9 vol.%)$ by pressure swing adsorption (PSA), the breakthrough curve was experimentally observed in a fixed bed adsorption column. A single adsorber was packed with various adsorbents such as, the activated carbon(S-AC, W-AC) and the molecular sieve(MS-5A, MS-13X). The order of appearance of breakthrough curve is MS-5A > MS-13X > W-AC > S-AC. The activated carbon was found to be more effective adsorbent for separating Freon-12 from the mixture than the molecular sieve was. From the experimental data obtained by the separation of Freon-12 gas out of the air stream in the steady-state PSA process cycle, whose size is the same one of column used for the breakthrough curve observation, it has been confirmed that Freon-rich gas could be obtained from the purge step of PSA and Freon-free air could be obtained from the adsorption step of PSA cycle.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2005.11b
• /
• pp.119-125
• /
• 2005

A method of predicting the tritium concentration in the air leaving an atmospheric detritiation dryer was modeled for designing a fixed bed dryer and preparing an advanced dryer control. In order to quantify the bed utilization and the dynamic capacity against an inlet humidity and a flow rate, a series of quantitative tests based on the break-through behavior were carried out in an isothermal fixed bed of synthetic zeolites such type as molecular sieve 4A, 5A, 13X and mordenite. The amount of water vapor breaking during the adsorption was estimated to give a breakthrough capacity at the various inlet flow rates and humidity conditions. The molecular sieve 13X exhibited a better adsorption performance at a given bed height.

• Korean Journal of Microbiology
• /
• v.27 no.2
• /
• pp.117-123
• /
• 1989

Radioactive N-$\alpha$-p-nitrobenzoxycarbonyl (NBZ)-L-[2,$3-^{3}$H] arginyl diazomethane was used as an affinity label for the vacuolar arginine transporter in Neurospora crassa. Vacuolar matrix proteins were removed by fracturing the membranes with freeze-thaw method in dry ice/ethanol bath. Vacuolar membrane proteins were then wasged with 500mM NaCl to remove ionically bound derivatives and peripheral membrane proteins from vacuolar membranes. After dissolved in 1% Titon X-100, dissolved vacuolar memvrane proteins were separated with molecular sieve column chromatography, anion and cation exchange chromatographies. The arginine transporter was purified giving the purification factor of 1136.

• Korean Membrane Journal
• /
• v.10 no.1
• /
• pp.39-45
• /
• 2008

Polyelectrolyte complex based on two anionic polysaccharides, composed of sodium alginate and carrageenan, were prepared by interacting with divalent calcium ions in solution. The effects of annealing on the structural deformation of polyelectrolyte complex and on their characteristics at removing water from a methanol mixture from the point of molecular sieve were investigated and discussed. The result showed that the structural deformation of the annealed polyelectrolyte complex has an effect on the free volume between these polymer chains and the chelate segments such a shrinking of the overall morphology, which act as a molecular sieve in the separation of methanol and water mixtures.

• Proceedings of the Membrane Society of Korea Conference
• /
• 2001.05a
• /
• pp.59-62
• /
• 2001

• Journal of the Korean Chemical Society
• /
• v.37 no.10
• /
• pp.917-919
• /
• 1993

• Clean Technology
• /
• v.9 no.4
• /
• pp.179-187
• /
• 2003

The technology of fluidized bed to use dry sorbent can be new technology that reduce the operating cost and make efficient operation. Therefore, this study investigated $CO_2$ control by dry sorbents with operating variables in a fluidized bed, compared with fixed bed for $CO_2$ adsorption capacity and pressure drop, and presented the $CO_2$ adsorption capacity of activated carbon, molecular sieve 5A, molecular sieve 13X, and activated alumina. As the results of this study, the basic data could be achieved for operation of fluidized bed process, and fluidized bed process presented relatively high $CO_2$ adsorption capacity and low pressure drop with the increase of gas velocity. In addition, molecular sieve 5A showed 1.1~3.0-fold later breakthrough point and 1.1~2.7-fold higher adsorption capacity than the other dry sorbents.

• Journal of the Korean Chemical Society
• /
• v.8 no.4
• /
• pp.188-191
• /
• 1964

A new gas-chromatographic method for determining carbon and hydrogen in organic compounds has been developed. After sample combustion was performed in a regular analytical combustion tube with an internal oxidant (a mixture of silver oxide and manganese dioxide) under a helium flow, the water produced was converted to acetylene by passing through a calcium carbide tube. The carbon dioxide and acetylene were trapped by a molecular sieve 5A column at room temperature. The trapped gases were released under programmed temperature raise up to $340^{\circ}C$ and the released gases were passed through a silica gel column. The adsorption of $CO_2$ and $C_2H_2$ in the molecular sieve 5A trapping column were found to be quantitative and the silica gel column showed an excellent resolution of $CO_2$ and $C_2H_2$ for analytical purpose. The analytical results for various known compounds based on the out-put of the thermal conductivity cell calibrated for the amounts of carbon and hydrogen contents in benzoic acid, showed average errors ${\pm}0.5%$ and ${\pm}0.33%$ for carbon and hydrogen, respectively.

• Membrane Journal
• /
• v.30 no.4
• /
• pp.260-268
• /
• 2020

Mixed-matrix carbon molecular sieve membranes containing conventional and hierarchically structured 5A were synthesized for application in oxygen (O₂)/nitrogen (N₂) separation. In general, incorporating 5A fillers into porous carbon matrices dramatically increased the permeability of the membrane with a marginal decrease in selectivity, resulting in very attractive O₂/N₂ separation performances. Hierarchical zeolite 5A, which contains both microporous and mesoporous domains, improved the separation performance further, indicating that the mesopores in the zeolite can serve as an additional path for rapid gas diffusion without sacrificing O₂/N₂ selectivity substantially. This facile strategy successfully and cost-effectively pushed the performance close to the Robeson upper bound. It produced high performance membranes based on Matrimid^® 5218 polyimide and zeolite 5A, which are inexpensive commercial products.

• Microbiology and Biotechnology Letters
• /
• v.37 no.4
• /
• pp.365-370
• /
• 2009

For the production of diglyceride (DG) containing medium chain fatty acid, which could be utilized as a substrate to structured lipid production, monoglyceride (MG) and caprylic acid were reacted in the presence of lipase. The reaction system was well mixed homogeneously without using any organic solvent. Among the lipases investigated, Lipozyme RM IM and Novozym 435 were selected on the basis of equilibrium DG yields from the medium chain fatty acid and MG. And reaction conditions such as addition of molecular sieve, water content of immobilized lipase, reaction temperature, and mole ratio of MG/caprylic acid are optimized to increase DG production by using Lipozyme RM IM. DG content of reaction mixture showed 8% increase by adding molecular sieve to reaction mixture. Removal of water from the immobilized lipase could affect seriously equilibrium content of DG. More than 2.8%(w/w) removal of water from the support could make 44% of DG. Optimum temperature was found to $60^{\circ}C$. Temperature shift from $60^{\circ}C$ to $25^{\circ}C$ resulted in increase of free fatty acid (FFA) content. The equilibrium DG yield was not seriously affected by on MG/caprylic acid molar ratio. However, at the stoichiometric ratio of 1:1 the highest DG yield was obtained. Increasing MG/caprylic acid ratio from 0.3 to 1.8 decreased FFA content from 34% to 13%, while MG content increased from 27% to 50%.