• Journal of the Korean Chemical Society
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• v.35 no.5
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• pp.506-511
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• 1991

A sensitive adsorptive stripping voltammetric study was investigated on the complex of indium with morin at a hanging mercury drop electrode in 0.1 M acetate buffer (pH 3.20) solution. The adsorption phenomena were observed by differential-pulse voltammetry. The effects of various analytical conditions were discussed on the reduction peak current of the adsorbed complex on the surface of HMDE. Interferences by other trace metals and surfactant were also discussed. Detection limit was 2.6 nM of indium after 90 second deposition time, and the relative standard deviation (n = 7) at 4TEX>${\mu}g$/l indium was 2.0%.

• Journal of Microbiology and Biotechnology
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• v.14 no.2
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• pp.250-255
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• 2004

The aim of this work was to investigate the adsorption isotherm and kinetic model for the biosorption of lead $(Pb^{2+})$ by Rhodotorula aurantiaca and to examine the environmental factors for this metal removal. Within five minutes of contact, $Pb^{2+}$ sorption reached nearly 86% of the total $Pb^{2+}$ sorption. The optimum initial pH value for removal of $Pb^{2+}$ was 5.0. The percentage sorption increased steeply with the biomass concentration up to 2 g/l and thereafter remained more or less constant. The Langmuir sorption model provided a good fit throughout the concentration range. The conformity of these data to the Langmuir model indicated that biosorption of $Pb^{2+}$ by R. aurantiaca could be characterized as a monolayer, single-site type phenomenon with no interaction between ions adsorbed in neighboring sites. The maximum $Pb^{2+}$ sorption capacity $(q_{max})$ and Langmuir constant (b) were 46.08 mg/g of biomass and 0.04 l/mg, respectively. The pseudo second-order equation was well fitted to the experimental data. The correlation coefficients for the linear plots of t/q against t for the second-order equation were 0.999 for all the initial concentrations of biosorbent for contact times of 180 min. The theoretical $q_{eq}$ value was very close to the experimental $q_{eq}$ value.

• Textile Coloration and Finishing
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• v.27 no.4
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• pp.301-308
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• 2015

This study optimizes dyeing conditions for polyamide-imide fabric using cationic dyes. Dyeing and fastness characteristics of polyamide-imide fabric were investigated with three cationic dyes and 2-hydroxyacetophenone as a swelling agent under various dyeing conditions such as dye and swelling agent concentrations, dyeing temperature and time, pH of dye bath. The dyeing properties were evaluated in terms of dye exhaustion, K/S value and color fastness. The optimized dyeing temperature and time were $130^{\circ}C$ for 90 min for the dyes. Under weak acidic conditions in the range pH 5 to 7, the exhaustion of cationic dyes could be enhanced leading to higher adsorption. Wash and rubbing fastness properties were generally good, while light fastness was slightly low, which can be attributed to the poor photo-stability of the cationic dyes.

• Economic and Environmental Geology
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• v.32 no.1
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• pp.101-111
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• 1999

Sedimentary organic matter, exposed to continental surficial environment, reacts with oxygen supplied from the atmosphee and forms carbon-containing oxidation products. Knowledge of the rate and mechanisms of sedimentary organic matter weathering is important because it is one of the major controls on atmospheric oxygen level through geologic time. Under the abiological conditions, the oxidation rate of coal organic matter by molecular oxygen is enhanced by the increase of oxygen concentration and temperature. At ambient temperature and pressure, aqueous coal oxidation results in the formation of dissolved $CO_2$ dissolved organic carbon and solid oxidation products which are all quantitatively significant reaction products. The effects of pH, ultraviolet light, and microbial activity on the weathering of sedimentary organic matter are poorly contrained. Based on the results of geochmical and environmental studies, it is believed that the photochemical reaction should play an important role in the decomposition and oxidation of sedimentary organic matter removed from the weathering profile. At higher pH conditions, the production rate of DOC can be accelerated due to base catalysis. These high molecular weight oranic matter can react with man-made pollutants such as heavy metal ions via adsorption/desorption or ion exchange reactions. The effect of microbial activity on the oxidative weathering of sedimentary organic matter is poorly understood and remains to be studied.

• Food Science and Biotechnology
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• v.18 no.5
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• pp.1150-1154
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• 2009

Low levels of virus contamination and naturally occurring reverse transcription-polymerase chain reaction (RT-PCR) inhibitors restrain virus detection in oysters. A rapid and efficient oyster-processing procedure that can be used for sensitive virus detection in oysters was developed. Poliovirus type 1 Sabin strain was used to evaluate the efficacy of virus recovery. The procedure included (a) acid-adsorption and elution with buffers (0.25M glycine-0.14 M NaCl, pH 7.5; 0.25M threonine-0.14M NaCl, pH 7.5); (b) polyethylene glycol (PEG) precipitation; (c) resuspension in Tween 80/Tris solution and chloroform extraction; (d) the second PEG precipitation; (e) viral RNA extraction with TRIzol and isopropanol precipitation; and (f) RT-PCR combined with semi-nested PCR. The overall recovery of elution/concentration was 19.5% with poliovirus. The whole procedure usually takes 19 hr. The overall detection sensitivity was 4 RT-PCR units of genogroup I norovirus (NoV) and 6.4 RT-PCR units of genogroup II Nov/25 g of oysters initially seeded. The virus-detecting method developed in this study should facilitate the detection of low levels of NoV in oysters.

• Applied Chemistry for Engineering
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• v.31 no.5
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• pp.495-501
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• 2020

In this study, zirconium fumarate of metal-organic framework (MOF-801) was solvothermally synthesized at 130 ℃ and characterized through powder X-ray diffraction (PXRD) analyses and porosity measurements from N₂ sorption isotherms at 77 K. The ability of MOF-801 to act as an adsorbent for the phosphate removal from aqueous solutions at 25 ℃ was investigated. The phosphate removal efficiency (PRE) obtained by 0.05 g/L adsorbent dose at an initial phosphate concentration of 60 ppm after 3 h was 72.47%, whereas at 5 and 20 ppm, the PRE was determined to be 100% and 89.88%, respectively, after 30 min for the same adsorbent dose. Brunauer-Emmett-Teller (BET) surface area and pore volume of the bare MOF-801 sample were 478.25 ㎡/g and 0.52 ㎤/g, respectively, whereas after phosphate adsorption (at an initial concentration of 60 ppm, 3 h), the BET surface area and pore volume were reduced to 331.66 ㎡/g and 0.39 ㎤/g, respectively. The experimental data of kinetic (measured at initial concentrations of 5, 20 and 60 ppm) and isotherm measurements followed the pseudo-second-order kinetic equation and the Freundlich isotherm model, respectively. This study demonstrates that MOF-801 is a promising material for the removal of phosphate from aqueous solutions.

• Journal of Hydrogen and New Energy
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• v.18 no.2
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• pp.164-170
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• 2007

The Tancheon wastewater treatment plant(WWTP) in Seoul using anaerobic digestion to reduce the outlet sludge produces anaerobic digester gas which contains 65% $CH_4$ and 35% $CO_2$. The gas purification equipment was installed and operated to use Anaerobic Digester Gas(ADG) as a fuel for molten carbonate fuel cell(MCFC). The processes consist of the desulfurizer and the adsorption tower to remove $H_2S$ and siloxane in the gas. The gas purification equipment removed virtually over 95% of $H_2S$ and over 99% of siloxane. Results has demonstrated that the fuel cell can produce electrical output and hot water with negligible air emissions of CO, NOx and $SO_2$. The site provides the first opportunity in Korea for demonstrating Molten carbonate fuel cell(MCFC) which the digester gas was applied to the fuel gas.

• Bulletin of the Korean Chemical Society
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• v.35 no.1
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• pp.141-146
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• 2014

A series of bimetallic Cu-Zn/$SiO_2$ catalysts were prepared via thermal decomposition of the as-synthesized $CuZn(OH)_4(H_2SiO_3)_2{\cdot}nH_2O$ hydroxides precursors. This highly dispersed Cu-solid base catalyst is extremely effective for hydrogenation of ethyl acetate to ethanol. The reduction and oxidation features of the precursors prepared by coprecipitation method and catalysts were extensively investigated by TGA, XRD, TPR and $N_2$-adsorption techniques. Catalytic activity by ethyl acetate hydrogenation of reaction temperatures between 120 and $300^{\circ}C$, different catalyst calcination and reduction temperatures, different Cu/Zn loadings have been examined extensively. The relation between the performance for hydrogenation of ethyl acetate and the structure of the Cu-solid base catalysts with Zn loading were discussed. The detected conversion of ethyl acetate reached 81.6% with a 93.8% selectivity of ethanol. This investigation of the Cu-Zn/$SiO_2$ catalyst provides a recently proposed pathway for ethyl acetate hydrogenation reaction to produce ethanol over Cu-solid base catalysts.

• Bulletin of the Korean Chemical Society
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• v.29 no.3
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• pp.609-614
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• 2008

A periodic mesoporous organosilica material was synthesized by microwave heating (PMO-M) using 1,2-bis(trimethoxysilyl)ethane as a precursor in a cationic surfactant solution, and textural properties were compared with those of the product produced by conventional convection heating (PMO-C). These synthesized materials were characterized using XRD, TEM/SEM, N2 adsorption isotherm, 29Si and 13C NMR, and TGA, which confirmed their good structural orders and clear arrangements of uniform 3D-channels. Synthesis time was reduced from 21 h in PMO-C to 2-4 h in PMO-M. PMO-M was made of spherical particles of 1.5-2.2 m m size, whereas PMO-C was made of decaoctahedron-shaped particles of ca. 8.0 m m size. Effect of synthesis temperature, time, and heating mode on the PMO particle morphology was examined. The particle size of PMO-M could be controlled by changing the heating rate by adjusting microwave power level. PMO-M demonstrated improved separation of selected organic compounds compared to PMO-C in a reversed phase HPLC experiment. Ti-grafted PMO-M also resulted in higher conversion in liquid phase cyclohexene epoxidation than by Ti-PMO-C.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3362-3366
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• 2013

A simple and quick separation technique for selenite in natural water was developed using $TiO_2$@$SiO_2/Fe_3O_4$ nanoparticles. For the synthesis of nanoparticles, a polymer-assisted sol-gel method using hydroxypropyl cellulose (HPC) was developed to control particle dispersion in the synthetic procedure. In addition, titanium butoxide (TBT) precursor, instead of the typical titanium tetra isopropoxide, was used for the formation of the $TiO_2$ shell. The synthesized nanoparticles were used to separate selenite ($Se^{4+}$) in the presence of $Se^{6+}$ or selenium anions for the photocatalytic reduction to $Se^0$ atom on the $TiO_2$ shell, followed by magnetic separation using $Fe_3O_4$ nanoparticles. The reduction efficiency of the photocatalytic reaction was 81.4% at a UV power of 6W for 3 h with a dark adsorption of 17.5% to the nanoparticles, as determined by inductively coupled plasma-mass spectrometry (ICP-MS). The developed separation method can be used for the speciation and preconcentration of selenium cations in environmental and biological analysis.