• Applied Chemistry for Engineering
• /
• v.10 no.1
• /
• pp.129-134
• /
• 1999

This study is related to the investigation of the direct incorporation of $CO_2$ to polymer using quaternary ammonium salt catalysts. Quaternary ammonium salts showed good catalytic activity of $CO_2$ fixation in the synthesis of poly[(1,3-dioxolane-2-oxo-4-yl)methyl methacrylate] [poly(DOMA)] by the direct incorporation of $CO_2$ to poly(glycidyl methacrylate)[poly(GMA)]. Among the salts tested, the ones with higher alkyl chain length and with more nucleophilic counter anion showed higher catalytic activity. The yield of carbon dioxide addition increased with the reaction temperature. Kinetic study was carried out by measuring the variation of $CO_2$, pressure in a high pressure batch reactor. The reaction rate was first order to the concentration of poly(GMA) and $CO_2$, respectively. The rate constant was $0.69L/mol{\cdot}h$ and Henry's constant of $CO_2$ in DMSO at $80^{\circ}C$ was $6.8{\times}10^{-4}mol/L{\cdot}KPa$.

• Membrane Journal
• /
• v.3 no.3
• /
• pp.126-135
• /
• 1993

Perchlorate ion-selective PVC membrane electrode responsive to $10^{-6}M$ was developed by incorporating the ion-pair complex of perchlorate with the quaternary ammonium salts as a active material. The effect of chemical structure, the content of active material, the kinds of plasticizers, and the membrane thickness on the electrode characteristics such as the linear response range and Nernstian slope of the electrode were studied. With the results, the useful pH range and the selectivity coefficients to various interfering anions were compared and investigated. It was obtained that the effect of the chemical structure of an active material on the electrode characteristics was improved with increasing the alkyl chain length of the quarternary ammonium salts in the ascending order of Aliquat 336P, TOAP, TDAP, and TDDAP. The electrode characteristics was improved with the decrease of the active material content below the optimum membrane composition, and DBP was the best as a plasticizer. The optimum membrane composition was 9.09wt% of TDDAP, 30.3wt% of PVC, and 60.6wt% of ptasticizer(DBP). And the optimum membrane thickness was0.45mm at this composition. Under the above condition, thelinear response ranger was $10^{-1}~1.2 {\times} 10^{-6}M$, and the detection limit was $5.1{\times}10^{-7}M$ with the Nernstian slope of 57mV/decade of activity of perchlorate ion. The electrode potential was stable within the pH range from 4 to 11. The selectivity coefficient was as shown below : $SCN^->I^->NO_3^->Br^->ClO_3^->F^->Cl^->SO_4^{2-}$

• Applied Chemistry for Engineering
• /
• v.31 no.3
• /
• pp.267-276
• /
• 2020

Poly(epichlorohydrin) copolyol series (PECH copolyols) were synthesized via cationic ring-opening copolymerization (ROCP) of oxirane-based monomers and effects of reaction temperature, solvent type, and initiator were studied. As a comonomer, two types of alkylene oxides were used, and polymerization conditions were conducted both with diethylene glycol (DEG) as an initiator in methylene chloride (MC) solvent and tripropylene glycol (TPG) in toluene solvent. In order to induce the active monomer (AM) mechanism in the ring-opening copolymerization reaction, the monomer was injected by an incremental monomer addition (IMA) method using a syringe pump, and the polymerization was performed at -5 ℃. PECH copolyol, a synthesized ephichorohydrin (ECH)-based copolyol, was converted to glycidyl azide-based energy-containing copolyol (GAP copolyol) by azadizing the ECH unit through a substitution reaction. It was confirmed that the synthesized azide copolyol had little effects on changes of the solvent and the initiator. Also, the molecular weight increased 500 after the azide reaction, thereby the GAP copolyol was polymerized as designed. As the content of the comonomer increased, both the T_g and viscosity tended to decrease due to the influence of the alkyl chain length. It is possible to fundamentally prevent CH₃N₃ amount produced in the azide reaction process, and it is expected that a large-scale process could be achievable.

• Journal of the Korean Applied Science and Technology
• /
• v.32 no.1
• /
• pp.31-39
• /
• 2015

The synergistic solvent extraction of rare earth elements such as europium and yttrium has been investigated by the extractant with crown ether as an additive. Macrocyclic ligand as host-guest compounds form more stable complexes with metal ions which have the similar size of the cavity of crown ether. In our previous study[14] founded that the extraction used fatty acid of the various alkyl chain length. Based on the results of the previous experiment, the synergistic separation effect of two metals investigated that the hexanoic acid had was the worst extraction effect which added a crown ether such as 18-crown-6 ether, 15-crown-5 ether, and 12-crown-4 ether. In this study, the concentrations of hexanoic acid have showed the separation effect, and then the concentrations and kind of crown ether are performed for synergistic extraction at the hexanoic acid concentration of the highest separation effect. As a results, the separation rate is the highest value of 1.72 at 0.05 M hexanoic acid, and 0.002M 15-crown-5 ether is the best value in other concentrations and kind of crown ether, it is about twice of using only hexanoic acid. Moreover, the extraction species of two metals has been founded $MLR_3{\cdot}3RH$ form when added the crown ether.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.2
• /
• pp.528-535
• /
• 2016

Two types of oleophilic acrylic prepolymers were prepared by the solution copolymerization of either ethyl acrylate (EA) or lauryl acrylate (LA) with hydroxy ethyl acrylate (HEA). For the formation of oil-absorbent materials, a mixed solution of the prepolymer and hexamethylene diisocyanate (HDI) as a cross-linker in toluene was applied to polypropylene knit velvet fabric through the conventional pad-dry-cure procedure. The gel fraction of the crosslinked resin, EA-HEA-HDI, increased with increasing feed ratio of HEA to total acrylate or HDI concentration. The oil absorbancy and retention ratio of the prepared materials were compared according to the add-on ratio of resin to fabric, and were assessed with n-decane, toluene, soybean oil, lubricant and bunker C oil as test oils. The optimal oil absorbancy of the materials were observed at around 6% of the add-on ratio for all these oils except for soybean oil. On the other hand, the oil retention ratio increased as the add-on ratio increased. Futhermore, heavier and more viscous oil generally showed higher oil retention ratios. In addition, the oil absorbancy of the materials treated with LA-HEA-HDI resin was higher than that treated with EA-HEA-HDI resin, which showed that the acrylic resins are more absorptive with increasing length of their side alkyl chain.

• Applied Chemistry for Engineering
• /
• v.10 no.6
• /
• pp.876-880
• /
• 1999

The surfactant self-diffusion coefficients of mixed micellar solutions of ionic and nonionic surfactants have been measured by the NMR pulsed field gradient spin echo(FT-PGSE) method. In addition, the line widths of $^1H$ NMR signal have been monitored. The system investgated are $C_{12}EO_5/SDS/D_2O$, $C_{12}EO_5/DTAC/D_2O$, and $C_{12}EO_8/SDS/D_2O$. In the sample series, the molar ratios of $D_2O$ to surfactant(ionic+nonionic) were kept constant while the surfactant mixing ratio was varied. For the $C_{12}EO_5$ system, the surfactant self-diffusion coefficient indicates minimum when the surfactant mixing ratio is about 20% ionic surfactant. The observed decrease in self-diffusion coefficients as nonionic surfactant was replaced by ionic surfactant is interpreted to mainly be due to an increased micelle-micelle repulsion. The increase in self-diffusion coefficients occurring at higher fraction of ionic surfactant is shown to be due to a decrease in micelle size. For the $C_{12}EO_8$ system, the effect of the surfactant mixing ratio is much weaker which can be understood by considering the molecular geometry and large headgroup area. The proton NMR line widths correlate well with the self-diffusion coefficients and broadening of the alkyl chain methylene signals is found when the self-diffusion coefficients is low.

• Applied Chemistry for Engineering
• /
• v.21 no.5
• /
• pp.509-513
• /
• 2010

Recently, an amount of waste electronic devices such as LED and trichromatic fluorescent lamp has increased with the development of electronic industry. Reportedly, rare earth metals such as yttrium and europium have been discovered in the waste electronic devices. In order to improve the selectivity of yttrium and europium, the effects of the following factors on recovery experiment have been considered : i) fatty acids with various alkyl chain lengths, ii) the concentration of extractant, and iii) pH. The results show that the extraction efficiencies decrease at the same pH with decreasing the concentration of extractant and so $pH_{0.5}$ (That value of pH in an aqueous phase at which the distribution ratio is unity at equilibrium: 50% of the solute is extracted (E = 0.5) only when the phase ratio is unity.) moves into higher pH. The highest selectivity of yttrium and europium was obtained with tetradecanoic acid as extractant. The extraction mechanism of yttrium and europium was varied with the change of concentration of the tetradecanoic acid. $MR_3$single-species was formed from the yttrium and europium ion in the extractant concentration less than 0.1 M. On the other hand, the yttrium or europium ion is solvated with three molecules of tetradecanoic acid monomer like $MR_3{\cdot}$ 3RH in the extractant concentration more than 0.1 M.

• Applied Chemistry for Engineering
• /
• v.19 no.5
• /
• pp.504-511
• /
• 2008

Two kinds of nitroazobenzene derivatives: 4-{4'-(nitrophenylazo)phenoxy}alkanoic acids (NAAn, n = 2~8, 10, number of methylene units in the alkyl chain) and 4-{4'-(nitrophenylazo)phenoxy}alkanoyl chlorides (NACn, n = 2~8, 10) were synthesized, and their thermotropic liquid crystalline behaviors were investigated. NAA6 formed an enantiotropic nematic phase, while the remainders, except NAA2, showed monotropic nematic phases. Isotropic-nematic transition temperature ($T_{iN}$) and change of entropy (${\Delta}S$) at $T_{iN}$ for both of NAAn and NACn varied by the change of n, and pronounced odd-even effects of n were also observed. However, the $T_{iN}$ and ${\Delta}S$ values of NAAn were much higher than those of NACn. This fact may be attributed to the hydrogen bonding between carboxyl groups. Thermal properties and degree of order in the mesophase and the magnitude of the odd-even effects of both NAAn and NACn were significantly different from those reported for 4-(alkoxy)-4'-nitroazobenzenes. It was discussed in terms of the differences in the molecular anisotropy and the temperature-dependent flexibility of the substituted groups.

• Applied Chemistry for Engineering
• /
• v.7 no.6
• /
• pp.1156-1163
• /
• 1996

This study is related to the investigation of the characteristics of quaternary ammonium salt catalyst on the addition reaction of carbon dioxide and glycidyl methacrylate(GMA) to form(2-oxo-1,3-dioxolane-4-yl)methacrylate(DOMA). Among the salts tested, the ones with higher alkyl chain length and with more nucleophilic counter anion showed a higher catalytic activity. Mixed catalysts of NaI and 18-crown-6 showed a good yield of DOMA, but when they are used alone, they showed no catalytic activity. The DOMA monomer was obtained in low polar solvents, while poly(DOMA) could be directly synthesized in aprotic dipolar solvents. Kinetic studies carried out by measuring $CO_2$ pressure in a high pressure batch reactor showed that the reaction rate was first order to the concentration of GMA and $CO_2$ respectively. The rate constant(k) was 0.56L/mol hr and Henry's constant(H') of $CO_2$ in diglyme at $80^{\circ}C$ was $6.5{\times}10^{-4}mol/L{\cdot}kPa$.

• Microbiology and Biotechnology Letters
• /
• v.39 no.3
• /
• pp.238-244
• /
• 2011

Biodiesel, mono-alkyl esters of long chain fatty acids, is one of the alternative fuels derived from renewable lipid feedstock, such as vegetable oils or animal fats. For decade, various lipases have been used for the production of biodiesel. However, the production of biodiesel by enzymatic catalyst has profound restriction in industry application due to high cost. To overcome these problems, many research groups have studied extensively on the selection of cheap oil sources, the screening of suitable lipases, and development of lipase immobilization methods. In this study, we produced biodiesel from plant oil using Proteus vulgaris lipase K80 expressed in Escherichia coli cells. The recombinant lipase K80 was not only expressed in high level but also had high specific lipase activity and high stability in various organic solvents. Lipase K80 could produce biodiesel from olive oil by 3-stepwise methanol feeding method. The immobilized lipase K80 also produced biodiesel using the same 3-stepwise method. The immobilized lipase could produce biodiesel efficiently from various plant oils and waste oils.