• Journal of Korean Society of Environmental Engineers
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• v.31 no.8
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• pp.663-672
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• 2009

In this studies, the adsorption test using Chlorella pyrenoidosa was conducted to examine the effect of Pb adsorption according to various immobilized methods such as Ca-alginate, K-carrageenan, and Polyacrylamide. From the results, the duration to need to reach adsorption equilibrium was delayed according to the immobilization. And, the higher adsorption capacity of immobilized Chlorella pyrenoidosa was represented in the higher concentration of Pb, the smaller amount of immobilizing agent, and the higher pH of solution. The maximum adsorption capacity of Pb was shown in the adsorption test using Chlorella pyrenoidosa immobilized with Ca-alginate even though it was sensitive pH. The adsorption results properly represented with Freundlich isotherm equations. And, pseudo second-order chemisorption kinetic rate equation was applicable to all the biosorption data over the entire time range. The FT-IR analysis showed that the mechanism involved in biosorption of Pb by Chlorella pyrenoidosa was mainly attributed to Pb binding of carbo-acid and amide group. Adsorbed Pb on immobilized Chlorella prenoidosa was easily desorbed in the higher concentration of desorbents(NTA, HCl, EDTA, $H_2SO_4,\;Na_2CO_3$). Among the several desorbents, NTA showed the maximum desoption capacities of Pb from Chlorella pyrenoidosa immobilized with Ca-alginate and K-carrageenan and EDTA was the most effective in Chlorella pyrenoidosa immobilized with polyacrylamide. The desoprtion efficiency in the optimum condition was 90.0, 83.0, and 80.0%, respectively.

• Analytical Science and Technology
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• v.18 no.4
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• pp.344-354
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• 2005

This study was carried out to evaluate the performance of a small chamber sampling and analytical method for the measurement of total volatile organic compounds (TVOC) and formaldehyde (HCHO) emission from building materials. While VOC was determined by the adsorbent tube sampling and sequential thermal desorption coupled with GC/MSD analysis, formaldehyde sampled with DNPH-silica cartridge was analyzed by HPLC. Wide-range performance criteria such as repeatability, desorption efficiency, emission chamber recovery test, duplicate precision, breakthrough volume and method detection limits were investigated for the evaluation of small chamber method. The overall precision of the small chamber sampling and analytical methods was estimated within 20~30% for target compounds. In conclusion, this study demonstrated that the small chamber sampling and analytical method can be reliably applied for the measurement of building materials pollutants.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.105-111
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• 2012

Manganese (Mn) catalysts were generated using $CeO_2$ and $ZrO_2$supports synthesized by the supercritical hydrothermal method and two different Mn precursors, aimed at an application for a low-temperature selective catalytic reduction process. Manganese acetate (MA) and manganese nitrate (MA) were used as Mn precursors. Effects of the kind and the concentration of the Mn precursor used for catalyst generation on the NOx removal efficiency were investigated. The characteristics of the generated catalysts were analyzed using $N_2$ adsorption-desorption, thermo-gravimetric analysis, X-ray diffraction, and X-ray photoelectron spectroscopy. De-NOx experiments were carried out to measure NOx removal efficiencies of the catalysts. NOx removal efficiencies of the catalysts generated using MA were superior to those of the catalysts generated using MN at every temperature tested. Analyses of the catalyst characteristics indicated that the higher NOx removal efficiencies of the MA-derived catalysts stemmed from the higher oxygen mobility and the stronger interaction with support material of $Mn_2O_3$ produced from MA than those of $MnO_2$ produced from MN.

• Korean Journal of Clinical Laboratory Science
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• v.52 no.1
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• pp.18-27
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• 2020

The correct distinction of carbapenem-resistant Enterobacteriaceae (CRE) and ccarbapenemase producing Enterobacteriaceae (CPE) and the rapid detection of CPE are important for instituting the correct treatment and management of clinical infections. Screening protocols are mainly based on cultures of rectal swab specimens on selective media followed by phenotypic tests to confirm a carbapenem-hydrolyzing activity, the rapid carbapenem inactivation method, lateral flow immunoassay, the matrix-assisted laser desorption ionization-time-of-flight test and molecular methods. The CPE is accurate for detection, and is essential for the clinical treatment and prevention of infections. A variety of phenotypic methods and gene-based methods are available for the rapid detection of carbapenemases, and these are expected to be routinely used in clinical microbiology laboratories. Therefore, to control the spread of carbapenemase, many laboratories around the world will need to use reliable, fast, high efficiency, simple and low cost methods. Optimal effects in patient applications would require rapid testing of CRE to provide reproducible support for antimicrobial management interventions or the treatment by various types of clinicians. For the optimal test method, it is necessary to combine complementary test methods to discriminate between various resistant bacterial species and to discover the genetic diversity of various types of carbapenemase for arriving at the best infection control strategy.

• Resources Recycling
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• v.12 no.3
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• pp.31-37
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• 2003

A study on the characteristics of ammonia desorption from aqueous solutions has been performed by air stripping as the first stage of ammonia recycling for the preparation of ammonium sulfate from it. For air stripping experiments, a stripping column made with acrylic tube of 40 mm diameter was employed and compressed air was injected into solutions through air sparger equipped at the bottom of stripping column. As a result of experiments, the stripping efficiency was increased with the aqueous pH and it was found that the appropriate pH for air stripping of ammonia was between pH 10 and 12. As far as the effect of air flow rate on ammonia stripping was concerned, ammonia stripping was not proportional to the air flow rate although it was affected by the air flow rate to some extent. Moreover, when more than 20 cm of water height was maintained, total ammonia desorbed from solution was not varied with the water height. Stripping temperature was also found to play an important role in ammonia desorption and about 90fo of initial ammonia was desorbed in 14 hours at pH 12.8 and at $60^{\circ}C$ Finally, it was believed that stripping temperature as well as the aqueous pH was one of the most important factors in air stripping of ammonia.

• Journal of the Mineralogical Society of Korea
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• v.18 no.4 s.46
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• pp.267-276
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• 2005

The study is to determine the feasibility of activated red mud as an anti-red tide material. The red mud, a byproduct of Bayer process for the production of alumina from bauxite, contained hematite, boehmite, calcite, sodalite, quartz, zircon, anatase and an unknown phase. In the adsorption study of the red mud, its adsorption efficiencies for heavy elements were close to $100\%$ except $92\%$ In As. These results seem to be attributed by the high adsorption ability of iron oxides for heavy elements. As a result of leaching tests with the red mud at various pHs (pH $1\∼13$), the high leaching efficiencies for As, Cu and Zn at low pHs (at acidic condition) were obtained. It indicated that removal efficiency of heavy elements could be excellent in acidic treatment of red mud. The activated red mud, red mud reacted with acid, contained hematite, boehmite and so on, and desorption of heavy metals from the activated red mud increased with increasing temperature. The grain of the activated red mud was tens nm in size. The removal efficiency for 5 types of plankton was generally in inverse proportion to pH, especially to final pH. Of five plankton types, Prorocentrum minimum and Alexandrium tamarense promptly were removed more than $90\%$ as soon as the activated red mud was sprayed and $100\%$ after 30 minutes. These results indicated that the activated red mud seems to be a promising anti-red tide material.

• Clean Technology
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• v.27 no.3
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• pp.223-231
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• 2021

In order to address many issues associated with large volume changes of silicon, which has very low electrical conductivity but offers about 10 times higher theoretical capacity than graphite (Gr), a silicon nanoparticles/hollow carbon (SiNP/HC) composite having bimodal-mesopores was prepared using silica nanoparticles as a template. A control SiNP/C composite without a hollow structure was also prepared for comparison. The physico-chemical and electrochemical properties of SiNP/HC were analyzed by X-ray diffractometry, X-ray photoelectron spectroscopy, nitrogen adsorption/desorption measurements for surface area and pore size distribution, scanning electron microscopy, transmission electron microscopy, galvanostatic cycling, and cyclic voltammetry tests to compare them with those of the SiNP/C composite. The SiNP/HC composite showed significantly better cycle life and efficiency than the SiNP/C, with minimal increase in electrode thickness after long cycles. A hybrid composite, SiNP/HC@Gr, prepared by physical mixing of the SiNP/HC and Gr at a 50:50 weight ratio, exhibited even better cycle life and efficiency than the SiNP/HC at low capacity. Thus, silicon/carbon composites designed to have hollow spaces capable of accommodating volume expansion were found to be highly effective for long cycle life of silicon-based composites. However, further study is required to improve the low initial coulombic efficiency of SiNP/HC and SiNP/HC@Gr, which is possibly because of their high surface area causing excessive electrolyte decomposition for the formation of solid-electrolyte-interface layers.

• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.125-130
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• 2010

In the present work, we have investigated the adsorption efficiency of carbon/iron oxide nanocomposite towards removal of hazardous brilliant green (BG) from aqueous solutions. Carbon/iron oxide nanocomposite was prepared by chemical precipitation and thermal treatment of carbon with ferric nitrate at $750^{\circ}C$. The resulting material was thoroughly characterized by TEM, XRD and TGA. The adsorption studies of BG onto nanocomposite were performed using kinetic and thermodynamic parameters. The adsorption kinetics shows that pseudo-second-order rate equation was fitted better than pseudo-first-order rate equation. The experimental data were analyzed by the Langmuir and Freundlich adsorption isotherms. Equilibrium data was fitted well to the Langmuir model with maximum monolayer adsorption capacity of 64.1 mg/g. The thermodynamic parameters were also deduced for the adsorption of BG onto nanocomposite and the adsorption was found to be spontaneous and endothermic.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.1
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• pp.126-146
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• 2000

To develop and evaluate formaldehyde measurement method using 2,4-dinitro-phenylhydrazine (2,4-DNPH) coated sampler and gas chromatography, laboratory test and field test were conducted. Results of this study are as follows. Limit of detection(LOD) of measurement methods, HPLC-UVD, GC-NPD and GC-FID, is $0.008{\mu}g/m{\ell}$ $0.060{\mu}g/m{\ell}$, $0.472{\mu}g/m{\ell}$ respectively. Coefficiency of measurement methods, HPLC-UVD, GC-NPD and GC-FID, is 0.008, 0.009, 0.020 respectively. Desorption efficiency of sep-pak xposure aldehyde sampler and sorbent sample tube is 1.05(range : 0.99 - 1.12), 1.02(range : 0.99 - 1.06) respectively. Samples of sorbent sample tube and sep-pak xposure aldehyde sampler turned out to be stored at refrigerator, according to storage test results. Measurement methods of HPLC-UVD, GC-NPD, GC-FID, according to results of precision for the combined sampling and analytical procedure, became acceptable to OSHA evaluation standard. Field test using exposure chamber met the NIOSH overall uncertainty recommendation(less than 25%). Overall uncertainty of Sepak-HPLC(UVD), Tube-GC(NPD), Tube-GC(FID) is 11.0% - 17.0%. Consequently gas chromatography(GC-NPD, GC-FID) and high performance liquid chromatography(EPA TO-11) using 2,4-DNPH coated sampler for formaldehyde measurement turned out to be suitable to measure personal formaldehyde exposure at workplaces.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1449-1454
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• 2014

The co-sensitization of N719 with a cyclic thiourea functionalized organic dye, coded AZ5, for dye-sensitized solar cells (DSSCs) was demonstrated. Due to its intensive absorption in ultraviolet region, AZ5 could compensate the loss of light harvest induced by triiodide, thereby the short-circuit photocurrent density ($J_{sc}$) was increased for co-sensitized (N719+AZ5) DSSC. Moreover, the electron recombination and dye aggregation were retarded upon N719 cocktail co-sensitized with AZ5, thus the open-circuit voltage ($V_{oc}$) of co-sensitized device was enhanced as well. The increased $J_{sc}$ (17.9 $mA{\cdot}cm^{-2}$) combined with the enhanced $V_{oc}$ (698 mV) ultimately resulted in an improved power conversion efficiency (PCE) of 7.91% for co-sensitized DSSC, which was raised by 8.6% in comparison with that of N719 (PCE = 7.28%) sensitized alone. In addition, co-sensitized DSSC exhibited a better stability than that of N719 sensitized device probably due to the depression of dye desorption.