• Clean Technology
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• v.17 no.2
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• pp.142-149
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• 2011

The adsorption and desorption behaviors of NO and $N_2O$ over two mixed oxide catalysts, AlCoPd (1/1/0.05) and AlCoFe (1/1/2), have been investigated for the lean $NO_x$ trap applications. The catalysts showed good adsorption capabilities for NO and $N_2O$ without needing oxidation step. The adsorption decreased a lot when they are co-adsorbed with oxygen. While NO kept high adsorbability and selectivity with respect to oxygen, those of $N_2O$ decreased sharply. From the TPD results, NO and $N_2O$ are considered to decompose into nitrogen and oxygen in the higher temperature range and the oxygen seems to be strongly attached to the catalysts even at high temperature.

• Bulletin of the Korean Chemical Society
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• v.25 no.5
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• pp.639-646
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• 2004

Metal treated activated carbons are prepared using various metals. Adsorption behaviors, morphologies, as well as antibacterial effects of metal treated samples are compared before and after solvent washing. Adsorption isotherms are used to characterize the porous structure of metal treated activated carbons before and after the solvent washing with acetone or ethyl alcohol. From these data, it is noticed that the changes in physicochemical properties of metal treated activated carbons depend on the solvents employed. Similar results are observed from BET data obtained from nitrogen adsorption isotherms. From scanning electron microscopy (SEM) studies, the changes in shape and size of metal particles are observed after the samples are washed with solvents. These changes result in different blocking effects, which, in turn, affect the adsorption behavior of metal treated activated carbons. X-ray diffraction (XRD) patterns of the samples treated with different metals are different each other. High intense sharp peaks attributed to metals are observed from silver treated samples, while the peaks are not observed from copper treated samples. To compare thermodynamic behavior of metal treated activated carbons washed with different type of solvents, differential scanning calorimetric (DSC) analysis is carried out. The analysis shows similar endothermic curves for all of the samples. Finally, antibacterial effects of metal treated activated carbon against Escherichia coli are discussed. Comparing the effects among the metals employed, highest effects are obtained from Cd, while lowest effects are obtained from Cu. Antibacterial activity becomes higher with the increase of the amount of metals treated, Optimum concentrations of metals to treat activated carbons, obtained from a shake flask test, are known to be 0.4, 0.1, and 0.6 moles for Ag, Cd, and Cu, respectively.

• Microbiology and Biotechnology Letters
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• v.41 no.1
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• pp.60-69
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• 2013

Purified melanin pigment from Klebsiella sp. GSK was characterized by thermogravimetric, differential thermal, X-ray diffraction and elemental analysis. This melanin pigment is structurally amorphous in nature. It is thermally stable up to $300^{\circ}C$ and emits a strong exothermic peak at $700^{\circ}C$. Its carbon, hydrogen and nitrogen composition is 47.9%, 6.9% and 12.0%, respectively. It was used to scavenge metal ions and free radicals. After immobilizing the pigment and using it to adsorb copper and lead ions, the metal ion adsorption capacity was evaluated by atomic absorption spectroscopy (AAS) and the identity of melanin functional groups involved in the binding of metal ions was determined by Fourier transform infrared (FT-IR) spectroscopy. Batch adsorption studies showed that 169 mg/g of copper and 280 mg/g of lead were adsorbed onto melanin-alginate beads. The metal ion adsorption capacity of the melanin-alginate beads was relatively significant compared to alginate beads. The metal ion desorption capacity of HCl was greater (81.5% and 99% for copper and lead, respectively) than that of EDTA (80% and 71% for copper and lead, respectively). The ability of the melanin pigment to scavenge free radicals was evaluated by inhibition of the oxidation of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and was shown to be about 74% and 98%, respectively, compared with standard antioxidants.

• Journal of Korea Soil Environment Society
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• v.4 no.2
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• pp.33-43
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• 1999

A strain (designated SK3l) which produces an excellent adsorption substance was isolated from soil samples and identified as Bacillus specied. The major adsorption substance (biosorbent SK3l) produced by Bacillus sp. SK31 was purified by ethanol precipitation and cetylpyridinium (CPC) precipitation. The adsorption charactics of zinc and lead ions on bioadsorbent SK3l were investigated. The equilibrium isotherms showed that bioadsorbent SK3l took up zinc and lead from aqueous solutions to the extent of about 52 mg/g and 112 mg/g. respectively. The culture conditions at the flask level of Bacillus sp. SK3l were investigated for the production of polysaccharide bioadsorbent, SK3l. The optimum pH and temperature for sorbent production were 7.5 and $30^{\circ}C$, respectively. The important carbon and nitrogen sources for sorbent formation were glucose and ammonium nitrate, respectively. In the optimized medium, sorbent production was improved three folds in comparison with the basal medium. In the jar fermenter, the highest sorbent production was obtained at 60 h cu1tivation time and the amount of biosorbent SK3l at that time was 9.2 g/$m\ell$.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.3 s.47
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• pp.321-328
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• 2004

Nano silica ball and nano carbon ball are developed commercially by template synthesis method. Adsorption of unpleasant smelling substances such as ammonia, trimethylamine, acetaldehyde and methyl mercaptane onto nano carbon ball with hollow macroporous core/mesoporous shell structures, nano carbon ball, was investigated and compared with that onto odor adsorbent materials, activated carbon, commercially available. The adsorption and decomposition of malodor at nano carbon ball exhibited superior than those onto activated carbon. The physicochemical properties such as mesopore size distributions, large nitrogen BET specific surface area and large pore volume and decomposition of malodor were studied to interpret the predominant adsorption performance. The nano carbon ball is expected to be useful in many applications such as deodorizers, adsorbent of pollutants.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.8
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• pp.761-766
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• 2010

This study was aimed to propose La(III)-zeolite composite which can effectively and simultaneously remove ammonia and phosphate in confined water bodies such as lakes and ponds. The optimum ratio of La(III):zeolite for the simultaneous removal of ammonia and phosphate was 0.0048 La(III) g:1 zeolite g. The drying temperature of La(III)-zeolite composite severely affected phosphate adsorption showing optimum condition at room temperature. It was revealed that the optimum dosage of La(III)-zeolite composite was 4.052 g/L at adsorption time of 90 min. The presence of alkalinity in aqueous solution brought positive effect on phosphate adsorption. Detachment of La(III) from La(III)-zeolite composite, which was dried at room temperature, was not observed in aquous solution. It indicates that La(III)-zeolite composite could effectively block phosphate released from sediment.

• Analytical Science and Technology
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• v.13 no.1
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• pp.89-95
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• 2000

Three grades of activated carbon fibers (ACFs) were prepared from various precursors of plantic, synthetic, and mixed fabrics of viscose rayon and cotton. The ACFs an exhibited type I isotherms on the adsorption of nitrogen or argon. Micropore analysis revealed that the ACFs have uniform micropore size distribution in which their peak diameters were in the range of $5.6{\pm}0.3{\AA}$. The BET surface area of ACFs up to $1600m^2g^{-1}$ was proportional to the adsorption capacity of iodine. The BET values of the ACFs prepared were proportional to the burn-off degree of the products.

• Journal of Applied Biological Chemistry
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• v.43 no.1
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• pp.25-30
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• 2000

The main form of nitrogen fertilizer applied to lowland rice is urea, but little is known about its transport in waterlogged soil. This study was conducted to investigate the transport of urea in waterlogged soil column using WAVE (simulation of the substances Water and Agrochemicals in the soil, crop and Vadose Environment) model which includes the parameters for urea adsorption and hydrolysis, The adsorption distribution coefficient and hydrolysis rate of urea were measured by batch experiments. A transport experiment was carried out with the soil column which was pre-incubated for 45 days under flooded condition. The urea hydrolysis rate (k) was $0.073h^{-1}$. Only 5% of the applied urea remained in soil column at 4 days after urea application. The distribution coefficient ($K_d$) of urea calculated from adsorption isotherm was $0.21Lkg^{-1}$, so it was assumed that urea that urea was a weak-adsorbing material. The maximum concentration of urea was appeared at the convective water front because transport of mobile and weak-adsorbing chemicals, such as urea, is dependent on water convective flow. The urea moved down to 11 cm depth only for 2 days after application, so there is a possibility that unhydrolyzed urea could move out of the root zone and not be available for crops. A simulated urea concentration distribution in waterlogged soil column using WAVE model was slightly different from the measured concentration distribution. This difference resulted from the same hydrolysis rate applied to all soil depths and overestimated hydrodynamic dispersion coefficient. In spite of these limitations, the transport of urea in waterlogged soil column could be predict with WAVE model using urea hydrolysis rate (k) and distribution coefficient ($K_d$) which could be measured easily from a batch experiment.

• Advances in nano research
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• v.8 no.1
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• pp.1-11
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• 2020

In order to develop a new adsorbent for removal of formaldehyde from aqueous solution, surface modification of TiO₂ nanoparticles was performed with 2,4-Dinitrophenylhydrazine (DNPH) that have a strong affinity to the formaldehyde. Sodium dodecyl sulfate (SDS) surfactant was used to improve the DNPH grafting to TiO₂ surface. Modified adsorbents were characterized by SEM, TEM, XRD, EDX and FTIR. Since the COD level in wastewaters including formaldehyde is considerable, it is necessary to determine the COD content of the synthetic wastewater. In order to determine the optimal removal conditions, the effect of contact time (60-210 min), pH (4-10) and adsorbent dosage (0.5-1.5 g/L) on adsorption and COD removal efficiencies were studied, using response surface method. EDX and FTIR analysis confirmed the presence of nitrogen-containing functional groups on the modified TiO₂ surface. The maximum formaldehyde adsorption and COD removal efficiencies by modified TiO₂ were about 15.65 and 7.35% higher than the unmodified nanoparticles respectively. Therefore, the grafting of nano-TiO₂ with DNPH would greatly improve its formaldehyde adsorption efficiency. The optimum conditions determined for a maximum formaldehyde removal of 99.904% and a COD reduction of 94.815% by TiO₂/SDS/DNPH nanocomposites were: adsorbent dosage 1.100 g/L, pH 7.424 and the contact time 183.290 min.

• Journal of Korean Society on Water Environment
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• v.22 no.2
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• pp.209-214
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• 2006

The purpose of this study is to improve the stream water quality by the experimental hybrid constructed wetland system. It consisted of the water layer, sand bed planted reeds, irises and roses, gravel bed, yellow-soil media bed and a flow shifter (FS) which can reverse top and bottom flow in the middle of the wetland. The organic compounds and nitrogen removal efficiencies varied with the seasons, namely temperature change. In summer, the mean efficiencies of COD and TN in the outflow from this wetland system were 63.4 and 48.0% and shown the highest, respectively, whereas, the suspended solids and phosphorus removal efficiencies seemed to be less affected by temperature. As a result of inspecting the decreasing trend of pollutants, nitrification-denitrification in the wetland was the major removal mechanism for nitrogen, the nitrogen reduction was especially enhanced by the application of a FS in the wetland, and phosphorus reduction was mainly occurred as a consequence of adsorption of the yellow-soil media.