• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.430-436
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• 2014

Allura Red (AR) is a water-soluble harmful tar-based food colorant (FD & C Red 40). Batch adsorption studies were performed for the removal of AR using bituminous coal based granular activated carbon as adsorbent by varying the operation parameters such as adsorbent dosage, initial concentration, contact time and temperature. Experimental equilibrium adsorption data were analyzed by Langmuir, Freundlich and Temkin isotherms. The equilibrium process was described well by Freundlich isotherm. From determined separation factor ($R_L$), adsorption of AR by granular activated carbon could be employed as effective treatment method. Temkin parameter, B was determined to 1.62~3.288 J/mol indicating a physical adsorption process. By estimation of adsorption rate experimental data, the value of intraparticle diffusion rate constant ($k_m$) increased with the increasing adsorption temperature. The adsorption process were found to confirm to the pseudo second order model with good correlation. Thermodynamic parameters like change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption in the temperature range of 298~318 K. The negative Gibbs free energy change (${\Delta}G$ = -2.16~-6.55 kJ/mol) and the positive enthalpy change (${\Delta}H$ = + 23.29 kJ/mol) indicated the spontaneous and endothermic nature of the adsorption process, respectively.

• Resources Recycling
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• v.33 no.4
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• pp.36-46
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• 2024

We investigated a hydrometallurgical process of nickel recovery from Inconel 713C scrap. The process proceeded with a series of i) comminution of pyrometallurgical treated scrap, ii) sulfuric acid leaching, iii) solvent extraction of unreacted acid, molybdenum, aluminum, and precipitation of chromium, iv) crystallization of nickel sulfate by vacuum evaporation, and v) nickel electrowinning. The nickel-aluminum intermetallic compound, Ni₂Al₃, was formed by the pyrometallurgical pretreatment readily grounded under 75 ㎛. Sulfuric acid leaching was done for 2 hours in 2 mol/L, 20 g/L solid/liquid ratio, and 80 ℃. It revealed that over 98 % of nickel and aluminum was dissolved, whereas 28 % of molybdenum was. A nickel sulfate solution with 2.34 g/L for the crystallization of nickel sulfate hydrate was prepared via solvent extraction and precipitation. Over 99 % of molybdenum and aluminum and 93 % of chromium was removed. Nickel metal with 99.9 % purity was obtained by electrowinning with the nickel sulfate monohydrate in the cell equipped with anion exchange membranes for catholyte pH control. The membrane did not work well, resulting in a low current efficiency of 73.3 %.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.24 no.1
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• pp.1-11
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• 2018

In this study, pro-oxidant($d2w^{(R)}$) and rPP/ZnO nanocomposite flexible films for food packaging were prepared, and their mechanical and antimicrobial properties were investigated. As a result, the carbonyl index and hydroxyl index increased with exposured time to heat and UV rays. Surface analysis showed that the addition of zinc oxide improved the dispersibility and compatibility of the polymer, so that the surface of the composite film was smooth and the zinc oxide particles were smaller than the compared film. And it kept the physical properties by heat and UV ray blocking effect, and it worked to reduce decomposition. In the antimicrobial activity test, the microbial reduction rate was 3 logs or more at the use concentration of zinc oxide. The tensile strength was increased and the elongation was decreased. Oxidative degradability of multi-layered film in UV exposured for 72 hours, the molecular weight of the film decreased by 75.6%, 1,294 g/mol Mn and 5,920 g/mol Mw. In the safety analysis of food packaging materials, we obtained that are in standard of polypropylene, a food contact material of domestic law.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.4
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• pp.551-554
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• 2012

The present laboratory investigation was conducted to assess the effect of heavy metals on carbon mineralization. Soil was treated with three concentrations (50, 100 and $150{\mu}mol\;g^{-1}$ soil) of two heavy metals (Cd and Zn) in a factorial combination of treatments replicated four times. Determination of carbon mineralization was carried out at 3, 7, 14, 21, 28, 42 and 56 days after metal treatments.. The amount of $CO_2$-C released from heavy metal treated soils was found to be decreased at an increasing rate during the first 28 days, followed by slow release as incubation progressed. The total amounts of $CO_2$-C released were 448, 382 and $348mg\;kg^{-1}$ soil respectively for soils treated with 50, 100 and $150{\mu}mol\;g^{-1}$ soil of Zn. The corresponding figures for Cd treated soils were 406, 354 and $282mg\;kg^{-1}$ soil implying that dose-dependent reduction in cumulative $CO_2$-C released from soils. The inhibition of carbon mineralization was found to be high in Cd treated soils than that of Zn treated. Therefore, tolerance and adaptation of the microbial community is likely to be related to the concentration and the type of metal. According to the results, carbon mineralization can be considered as possible indicator of soil pollution by means of heavy metals.

• Journal of Food Hygiene and Safety
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• v.22 no.4
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• pp.248-256
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• 2007

In this study, the competitive polymerase chain reaction (cPCR) was used to develop a direct enumeration method of Salmonella spp. in pork meat. After comparing three DNA extraction methods, the modified guanidine thiocyanate-phenol-chloroform method was chosen for Salmonella DNA extraction in artificially inoculated pork meat. The previously reported 284-bp invA gene (Rahn et al. Mol. Cell. Probes 1992) was tested for specificity, and 57 Salmonella strains and 24 non-Salmonella strains were evaluated. All Salmonella strains tested were invA positive, and all non-Salmonella strains produced no false positive amplification products. The detection limit achieved was as low as 1,460 colony-forming units (cfu) per 0.1g of pork meat. For cPCR, the invA gene, which features a 82 bp-deletion, was cloned in the pGEM-4Z vector. A known amount of competitor DNA, which has the same primer binding sites, was co-amplified with Salmonella chromosomal DNA from the artificially inoculated pork meat. The cell-number determined by cPCR was approximately equal to the cfu from the most probable number (MPN) method. Finally, the whole procedure took only 5 hr.

• Elastomers and Composites
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• v.48 no.1
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• pp.10-17
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• 2013

Polyolefin-g-poly(t-butylstyrene) as one of the high-temperature polyolefin-based thermoplastic elastomers was synthesized by the graft-from anionic living polymerization from the styrene moieties of the linear poly(ethylene-ter-1-hexene-ter-divinylbenzene) as a soft block to form the hard end blocks, poly(t-butylstyrene). The chemistry of the anionic graft-from polymerization involved complete lithiation of the pendant styrene unit of the soft polyolefin elastomer with sec-BuLi/TMEDA followed by the subsequent graft anionic polymerization of 4-tert-butylstyrene with Mn=10,000~30,000 g/mol. The graft-from living anionic polymerization were very effective and the grafting size increased proportionally with increasing monomer concentration and the reaction times. The synthetic methodology for the multi-hydroxyl chain-end modified polyolefin-g-poly(t-butylstyrene) was proposed by using the thiol-ene click reaction between 2-mercaptoethanol and the polyolefin-g-[poly(t-butylstyrene)-b-high vinyl polyisoprene], which was obtained from the subsequent living block copolymerization using polyolefin-g-Poly(t-butylstyrene) with isoprene. The result indicated that this process produced a new well-defined functionalized graft-type polyolefin-based TPE with high $T_g$ hard block(> $145^{\circ}C$).

• Bulletin of the Korean Chemical Society
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• v.26 no.6
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• pp.943-946
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• 2005

An effective spectrophotometric determination of palladium with 4-(2-pyridylazo)-resorcinol (PAR) using molten naphthalene as a diluent has been studied. A red complex of palladium with PAR is formed at 90 ${^{\circ}C}$. In the range of pH 9.0-11.0, the complex is quantitatively extracted into molten naphthalene. The organic phase is anhydrously dissolved in $CHCl_3$ to be determined spectrophotometrically at 520 nm against the reagent blank. Beer’s law is obeyed over the concentration range of 0.1-2 ${\mu}g{\cdot}mL^{-1}$. The molar absorptivity and Sandell’s sensitivity are 8.0 ${\times}\;10^5\;L{\cdot}mol^{-1}{\cdot}cm^{-}1\;and\;0.49\;{\mu}g{\cdot}cm^{-2}$ respectively. From the results of tolerance limits, it was found that there was no interferences were observed for most of the ions examined and those somewhat high interferences by Co(II), Fe(II) and Bi(III) could be effectively masked by EDTA.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.4
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• pp.385-390
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• 1999

HPLC method usually has been used for the determination of ATP and its related compounds in fish muscle and fish sauce. But, total amount of ATP related compounds in fish sauce is determined less than that of fish muscle. In order to establish the extract analysis method for ATP related compounds in fish sauce, a new enzymatic method was developed and compared with existing HPLC method. Fish sauce was extracted with chilled perchloric acid and neutralized to Ph 7.0 with potassium hydroxide solution, the extract was used as sample analyzed by HPLC as usual. On the other hand, for sample analyzed by enzymatic method, 1 ml extract solution was pipetted into test tube. To the tube, 0.5ml of mixed suspension adenosinedeaminase (4U), nucleosidephosphorylase (0.02U) and xanthineoxidase (0.03U) suspended in 2.0ml of 1/15 M sodium phosphate buffer solution pH 7.6 and 1.5ml deionized water wereadded for the decomposition of IMP, HxR and Hx to uric acid at $37^{\circ}C$ for 40 minutes. Total uric acid was determined by measuring optical density at 290nm. In HPLC method, salt decreased the total amount of ATP related compounds by $13.6\~16.2\%$ at $2.5\%$ concentration, but no effect in enzymatic method. IMP, HxR and Hx were detected at 254nm, while uric acid at only 290nm. The ratio of the total amount of ATP related compounds by HPLC method was about $45\%$ of that by enzymatic method in fish sauce. Form these results, enzymatic method is more accurate and simple than HPLC method for analysis of ATP related compounds in fish sauce.

• Polymer(Korea)
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• v.36 no.6
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• pp.693-698
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• 2012

In this study aluminum isopropyl oxide ($Al(O-i-Pr)_3$) was supported on the amine-functionalized surface of silica to synthesize high molecular weight (MW) polylactide (PLA), and it was tested for PLA polymerization behaviors. A silica was funtionalized with silane compound having amine groups, then in-situ treated with $Al(O-i-Pr)_3$. $Al(O-i-Pr)_3$ attached to amine group on silica showed activity only in the presence of MAO (methyl aluminoxane). At the polymerization temperature of $115^{\circ}C$, the conversion and the MW of PLA were increased as the amount of silane was increased. At the polymerization temperature of $130^{\circ}C$, the conversion was decreased while the MW was increased drastically and reached to MW 44000 g/mol when the amine concentration was 3.0 mmol/g. A bimodal type GPC curve was shown at the polymerization temperature of $115^{\circ}C$. As the amount of amine group increased, the peaks of GPC curve were merged. At the polymerization of $130^{\circ}C$, a unimodal GPC curve was shown. $Al(O-i-Pr)_3$ supported on amine-functionalized silica was able to produce higher MW PLA with enhanced activity compared to homogeneous $Al(O-i-Pr)_3$.

• Journal of the Korean Magnetics Society
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• v.17 no.6
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• pp.232-237
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• 2007

We have synthesized the low temperature sintered of Ni-Zn-Cu ferrite with nonstoichiometric composition a little deficient in $Fe_2O_3$ from $(Ni_{0.2}Cu_{0.2}Zn_{0.6})_{1+x}(Fe_2O_3)_{1-x}$. For low loss and acceleration of grain growth $TiO_2$ and $Li_2CO_3$ was added from 0.25 mol% to 1.0 mol%. The mixture of the law materials was calcinated and milled. The compacts of toroidal type were sintered at different temperature $(875^{\circ}C,\;900^{\circ}C,\;925^{\circ}C\;950^{\circ}C)$ for 2 hours in air followed by an air cooling. Then, effects of composition and sintering temperatures on the physical properties such as density, resistivity, magnetic induction, coercive force, initial permeability, and quality factor of the Ni-Zn-Cu ferrite were investigated. The density of the Ni-Zn-Cu ferrite was $4.85\sim5.32g/cm^3$, resistivity revealed $10^8\sim10^{12}\Omega-cm$. The magnetic properties obtained from the aforementioned Ni-Zn-Cu ferrite specimens were 1,300 gauss for the maximum induction, 4.5 oersted for the coercive force, 275 for the initial permeability, and 83 for the quality factor. The physical properties indicated that the specimens could be utilized as the core of high frequency range (involved microwave range) communication and deflection yoke of T.V.