• Membrane Journal
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• v.24 no.2
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• pp.100-106
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• 2014

In this work, soluble polyimides were synthesized and characterized from 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride (DOCDA) and two diamines such as 4,4'-diaminodiphenylether (ODA), 1,4-phenylenediamine (p-PDA). Their thermal properties were analyzed with differential scanning calorimeter (DSC). The gas permeability coefficients (P) and ideal selectivity for $CH_4$ and $CO_2$ of the prepared polyimide membranes were measured with a time-lag apparatus. DOCDA-ODA, DOCDA-p-PDA showed good permeability and selectivity; the permeabilities of $CO_2$ was 6.10, 0.74 barrers and the selectivity of $CO_2/CH_4$ were 67.03, 46.25, respectively. Therefore, DOCDA-ODA showed good possibility as gas separation membrane.

• Membrane Journal
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• v.24 no.1
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• pp.1-9
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• 2014

In this study, four soluble homo- and co-polyimides using 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride (DOCDA) and 4,4'-diaminodiphenyl ether (ODA) monomers were synthesized to develop the gas separation membrane with good $CO_2/CH_4$ separation properties. To prepare the copolyimides, 20 mol% of three dianhydrides - (4,4'-(hexafluoroisoproplidene)diphthalic anhydride (6FDA), 4,4'-biphthalic anhydride (BPDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) - were added in DOCDA-ODA monomer mixture, respectively. All the synthesized homo- and co-polyimides were characterized by FT-IR. Their thermal properties were analyzed with differential scanning calorimeter (DSC). Dense membranes were prepared from these copolyimides to check their gas permeation properties for $CO_2$ and $CH_4$ gases using a time-lag method. The permeation testing results are as follows; DOCDA/ODA homopolymer showed 1.71 barrer of $CO_2$ permeability and 74.35 of $CO_2/CH_4$ selectivity. The three polyimide copolymers (DOCDA/6FDA-ODA, DOCDA/BPDA-ODA, DOCDA/BTDA-ODA) showed lower $CO_2/CH_4$ selectivities and higher $CO_2$ permeabilities than the homopolymer (DOCDA-ODA). DOCDA/6FDA-ODA showed twice times higher $CO_2$ permeabilities without severe $CO_2/CH_4$ selectivity loss than the DOCDA-ODA.

• Journal of the Korean Applied Science and Technology
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• v.24 no.1
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• pp.92-97
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• 2007

The present paper deals with gaseous carbon dioxide separation by a commercial adsorbent: X-type zeolite. Experimental work was carried out at an ambient condition focusing on how well meeting to the national guideline. A few types of reactor and material were examined, and practical capability was found in a granular bed type reactor with the flow of 2.5 CMM. An optimum design of reactor and adsorbent could provide the required concentration, less than 2500 ppm, for the continuous operation up to 10 hours. More work including automatic regeneration is now underworking.

• Membrane Journal
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• v.23 no.5
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• pp.384-391
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• 2013

We prepared composite membrane which was made with polysulfone supported hollow fiber membrane coated with Hyflon AD to eliminate $CO_2$ gas from mixed-gases which were generated in DME manufacturing processes. The performance of module about simulated flaring gas was measured by using manufactured composite membrane. 1-stage evaluation result shows $CO_2$ concentration was below 3% at 1.2 MPa and at Stage cut 0.24 above. In addition $CO_2$ removal rate and $CH_4$ recovery rate was 80% respectively at the same condition. 2-stage evaluation result shows, when the $CO_2$ concentration of product gas was fixed at 5%, recycled $CO_2$ at stage cut 0.074 had the same concentration as the feed gas and the recovery rate of $CH_4$ was 99% at the moment.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.21-24
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• 2003

Methane steam reforming (MSR) was studied in a membrane reactor (MR) with a Pd-based and a porous alumina membranes. MRs showed methane conversion higher than that foresaw by the thermodynamic equilibrium for a traditional reactor (TR). Silica membranes prepared at KRICT were characterized with permeation tests on single gases ($N_2$, $H_2$ and $CH_4$). These silica membranes can be also used for high temperature applications such as $H_2$ separation $CO_2$ hydrogenation for methanol production is another reaction where $H_2O$ selective removal can be performed with these silica membranes.

• Polymer(Korea)
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• v.24 no.1
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• pp.1-7
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• 2000

The ACF/PP-g-AAc copolymers were synthesized by the irradiational grafting of acrylic acid onto ACF/PP fabric. The synthesis of copolymer was evidenced by the bands at 1720, 3600~3100 $cm^{-1}$ / on FT-IR spectrum. After the adsorption of metal ions on ACF/PP-g-AAc copolymers, the morphology with the small deposits on the fiber surface were observed by SEM. The optimal time for the metal ion adsorption equilibrium on ACF/PP-g-AAc copolymers was 24 hrs and their adsorption capacities increased in the order of Mn$^{2+}$>Cu$^{2+}$>Co$^{2+}$>Ni$^{2+}$. The adsorption capacities of ACF/PP-g-AAc copolymers were invariable after more than 10 times of regeneration.eration.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.705-708
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• 2001

Enzymatic synthesis and purification of sugar esters using supercritical $CO_2$ were investigated. The observed yield of suagr ester produced by transesterification of methyl glucoside and oleic acid using a lipase(Novozym 435) was 67% at 24 hours of reaction in the supercritical $CO_2$. The solubility of the fatty acids in the supercritical $CO_2$ was measured to find the conditions of supercritical separation of the fatty acids from the reaction mixture. The solubility of capric and oleic acid was 5 ${\times}$ $10^{-4}$, 1.7 ${\times}$ $10^{-4}$ mol/mol $CO_2$, respectively, varying at $35{\sim}50^{\circ}C$ and 80${\sim}$120 atm.

• Resources Recycling
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• v.24 no.5
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• pp.80-86
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• 2015

The separation of In from the synthesis solution with Ga, Fe, and Al has been studied by the solvent extraction using D2EHPA as an extractant. The effects as a function of the concentration of extractant and HCl on the extraction of In were investigated. The extraction of In and Ga increased with decreasing HCl concentration, but that of Fe and Al was independent. Separation factor between In and Ga of 115 was obtained at 1.0 M D2EHPA in the presence of 0.5 M HCl of feed solution. Consequently, this study shows that D2EHPA is suitable extractant for In extraction from the synthesis solution. Extraction efficiency and separation factor could be increased by controlling HCl and extractant concentration.

• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.483-489
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• 2007

Polyaniline (PANI)/Polyimide (PI) membranes were prepared and the effects of PANI contents and doping on the structural properties and gas separation properties were studied. The polyamic acid (PAA) solution was prepared by the polycondensation reaction of 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and 4,4'-oxydianiline (ODA) in 1-methyl-2-pyrrolydinone (NMP) solvent. The PANI/PI blends were obtained by mixing PAA solution and PANI solution, and were doped with 1 M aqueous HCl solution for 24 h. The structural characterizations of the as-cast and doped membranes were examined by FT-IR, XRD, and TGA. The gas permeation experiments with $H_2$, $CO_2$, $O_2$, $N_2$, and $CH_4$ were carried out by variable pressure method at $30^{\circ}C$ and 5 atm. For all gases tested, the permeability coefficients of the blends decreased with increasing PANI content and the magnitude of permeability was in the order of $H_2$ > $CO_2$ > $O_2$ > $N_2$ > $CH_4$. The permeability for PANI/PI membranes decreased after the doping process while the permselectivity increased. For $H_2/CH_4$ separation, the doped PANI/PI (75/25) membrane has a permselectivity of 991.

• Journal of Animal Reproduction and Biotechnology
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• v.35 no.2
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• pp.142-148
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• 2020

The research work was undertaken to determine an effective fertilization medium, sperm separation method and sperm capacitating agent for optimum in vitro fertilization (IVF) rates of indigenous zebu cow oocytes. In experiment 1, tissue culture medium (TCM 199), Tyrode's albumin lactate pyruvate (TALP) and Brackett and Oliphant (BO) medium were used as basic medium for IVF of oocytes of indigenous zebu cows. In experiment 2, three sperm separation methods namely centrifugation, swim up and percoll gradient methods were used for separation of motile and viable spermatozoa for IVF. In experiment 3, for capacitation of spermatozoa, IVF medium supplemented with the heparin, mixture of penicillamine, hypotaurine and epinephrine (PHE) or the combination of heparin with PHE were used for fertilization. In vitro culture (IVC) of presumptive zygotes was done in modified synthetic oviduct fluid (mSOF) medium using standard procedure 24 h after sperm-oocytes co-culture. The cleavage rate was determined to evaluate the efficacy of fertilization medium, sperm separation method and sperm capacitating agent 24 h after IVC. The cleavage rate was higher in oocytes fertilized in TALP (63.3%) than in TCM 199 (47.5%) (p < 0.05). The cleavage rate was higher in oocytes fertilized by spermatozoa separated by percoll gradient method (62.3%) than by centrifugation (51.6%) (p < 0.05). The cleavage rate of oocytes was higher when insemination was done with spermatozoa capacitated in TALP supplemented with heparin and PHE (61.3%) compared to control (40.9%) (p < 0.05). In conclusions, TALP based medium and percoll gradient sperm separation followed by capacitation with combination of heparin and PHE are suitable for IVF of indigenous zebu cow oocytes in Bangladesh.