• 분석과학
• /
• 제11권5호
• /
• pp.341-346
• /
• 1998

$Cu^{2+}$을 2-피리딘카르복살데히드(PyTC)와 반응시켜 $[Cu(PyTC)H_2O)]SO_4$를 얻었다. 이화합물은 1:1 전해질이며 물과 극성 유기 용매에 아주 잘 녹았다. 이 착물의 원소분석, 전기전도도 및 분광학적 데이터에서 이화합물의 구조는 사각평면임을 제시하였다. PyTC를 이용한 Cu(II)의 정량 가능성에 대하여 연구하였다. 구리(II)의 PyTC용액은 pH 4에서 $2.9{\times}10^{-4}M$까지 Beer의 법칙에 따랐다.

• 한국대기환경학회지
• /
• 제13권4호
• /
• pp.285-296
• /
• 1997

The suspended particulate matters had been collected on quartz fiber fiters by a cascade impactor having 9 size stages for 4 years (Sep. 1991 to Dec. 1995) in Kyung Hee University-Suwon Campus. Membrane filters were used to collected the particulate matters on each stage. The weight concentration on each stage was obtained by a microbalance and further chemical element levels were determined by an x-ray fluorescence system. Based on these chemical information, our study focused on applying the target transformation factor analysis (TTFA), a receptor model, to identify aerosol sources and to apportion quantitatively their mass contribution. There are total of 63 ambient data sets. Each data set consists of the 8 size-ranged subdata sets characterized by 16 elemental variables. By the results, four to five sources were extracted from each size range and some sources reappeared in other size ranges. Then total of 8 source profiles were statistically generated from all the ranges, such as oil burning source, soil source, field burning source, gasoline related source, coal burning source, marine source, glass related source, and unknown sources. Apportioning aerosol mass to each source was intensively examined by investigating emission inventories near the study area. The results showed that soil particle source was the most significant contributor. However, coal and oil burning sources were the major anthropogenic ones. The study finally proposed some air quality control strategies to achieve the clean air quality in Suwon area.

• 한국결정성장학회지
• /
• 제14권2호
• /
• pp.37-46
• /
• 2004

The electrochemical adsorption of the Ag ions from aqueous solution on pelletized activated carbon monolith was investigated over wide range of operation time. The adsorption capacities of pelletized activated carbon monolith are associated with their internal porosity and are related properties such as surface area, pore size distribution. The chemical industry generates wastewater that contains toxic matters like heavy metals in small concentrations so that their economic recovery is not feasible. But, the method using activated carbon monolith can be used to withdrawal of heavy metals in waste water. After the electrochemical treatment, the quantitative properties in Ag ion solutions are also examined by pH concentration and studied elemental analysis by ICP-Atomic Emission Spectrometer and Energy Disperse X-ray (EDX) spectra. It is consider that the pH is very important factor at the reason of water pollutant with increasing acidity in industrial field. The result of quantitative analysis using Inductively Coupled Plasma-Atomic Emission Spectrometer of metal after electrochemical reaction in Ag ions solution depending on time are shown that the amount of Ag ions deposited was decreased with growth of Ag particles on the carbon surfaces as increasing electrochemically treated time. And, surface morphologies are investigated by scanning electron microscopy (SEM) to explain the changes in adsorption properties.

• 한국결정성장학회지
• /
• 제19권5호
• /
• pp.268-276
• /
• 2009

In this study, activated carbon (AC) was treated with ferric ion by a sol-gel method. The compound (Fe-AC) was employed for the preparation of Fe-activated carbon/$TiO_2$, (Fe-AC/$TiO_2$) composites. The prepared Fe-AC/$TiO_2$ composites were characterized with surface properties, structural crystallinity, elemental identification and photocatalytic activity. The SEM results showed that ferric compounds and titanium dioxide were fixed onto the AC surfaces. The XRD results showed that Fe-AC/$TiO_2$ composites mostly contained anatase phase. EDX showed the presence of C, O, and Ti with Fe peaks in all samples. Its photocatalytic degradation effect was evaluated with the degradation behavior of the methylene blue (MB) solution. MB degradation could be attributed to the synergetic effects of adsorption, photo-degradation of $TiO_2$ and photo-Fenton of Fe component. The degradation rate for this photocatalysis was evaluated as a function of the concentration of the dye, the amount of $TiO_2$ and the pH. Photocataytic activity is good at activity pH.

• Nutritional Sciences
• /
• 제9권3호
• /
• pp.190-194
• /
• 2006

Silajit is a blackish brown pitch-like gummy substance. It is an important Unani and Ayurvedic medicine widely used in the treatment of many diseases and as nutritional supplement It is found in certain mountainous regions of Pakistan, Afghanistan, India, Nepal, Australia and Russia. Silajit samples of Pakistani origin were obtained from different sources and analyzed for their physical characteristics and biochemical & elemental composition. X-ray diffraction studies on Silajit showed that it is an amorphous substance and has no crystalline structure. Also, pH studies of Silajit (2 g/L of water) indicated that it was slightly acidic in nature and ranged from 3.45 to 7.23. Conductivity ranged from 157.7 to 330. Amino acid analysis revealed that Silajit contained lysine and alanine in higher amounts than all other amino acids and ranged from 1456 to 2240 and 68 to $1615{\eta}mole/g$, respectively. Mean concentration of arsenic, mercury, cadmium, lead, copper and zinc was 73.15, 104.92, 0.496, 3.89, 4.04 and 17.23 ppm, respectively. Silajit samples were also analyzed for calcium, potassium and sodium.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
• /
• pp.258-259
• /
• 2005

[ $CuInSe_2$ ] thin films were fabricated at various fabrication conditions (substrate temperature, sputtering pressure, BC/RF power, vapor deposition, heat treatment). And structural and electrical properties were measured in order to certify optimum conditions for growth of the ternary compound semiconductor $CuInSe_2$ thin films with stoichiometric composition. $CuInSe_2$ thin film was well made at the heat treatment of 500[$^{\circ}C$] of SLG/Cu/In/Se stacked elemental layer which was prepared by sputter and thermal evaporator, and chemical composition of the thin film was analyzed nearly as the proportion of 1 : 1 : 2. At the same time, carrier concentration, hall mobility and resistivity of the thin films was $1.27\sim9.88\times10^{17}[cm^{-3}]$, $49.95\sim185[cm^2/V{\cdot}s]$ and $10^{-1}\sim10^{-2}[\Omega{\cdot}cm]$, respectively

• Journal of Korean Society for Atmospheric Environment
• /
• 제19권E3호
• /
• pp.99-120
• /
• 2003

Visibility impairment in an urban area is mainly caused by airborne fine particulate matters. Visibility in a clean air environment is more sensitive to the change of PM$_{2.5}$ particle concentrations. However, a proportionally larger reduction in fine particle concentration is needed to achieve a small increment of visibility improvement in polluted areas. Continuous optical monitoring of atmospheric visibility and extensive aerosol measurements have been made in the urban atmosphere of Kwangju, Korea. The mean for fine particulate mass from 1999 to 2002 at Kwangju was measured to be 23.6$\pm$20.3 $\mu\textrm{g}$/㎥. The daily average seasonal visual range was measured to be 13.1, 9.2, 11.0, and 13.9 km in spring, summer, fall, and winter, respectively. The mean light extinction budgets by sulfate, nitrate, organic carbon, and elemental carbon aerosol were observed to be 27, 14, 22, and 12%, respectively. It is highly recommended that a new visibility standard and/or a fine particle standard be established in order to protect the health and welfare of general public. Much more work needs to be done in visibility studies, including long-term monitoring of visibility, improvement of visibility models, and formulating integrated strategies for managing fine particles to mitigate the visibility impairment and climate change.e.

• 분석과학
• /
• 제12권4호
• /
• pp.346-353
• /
• 1999

For the non-destructive multi-elemental analysis of environmental and biological materials, instrumental neutron activation analysis (INAA) was applied for the determination of toxic and trace elements in a set of three Algae samples provided by the International Atomic Energy Agency (IAEA). The analytical quality control was evaluated by comparing the analytical results of two standard reference materials of the National Institute of Standards and Technology (NIST); Oyster Tissue (SRM 1566a) and Citrus Leaves (SRM 1572). According to given analytical procedure, the concentration of 15-25 elements including spiked elements such as As, Cd, Cr and Hg in Algae samples were determined. To identify and validate these results, a data intercomparison program using more than 35 analytical methods in 150 laboratories was carried out and the estimated statistical data are summarized. Result of INAA is favorable, therefore, it is illustrated that can be applied for routine analysis of essential and toxic elements in algae samples as well as analytical quality assurance.

• Journal of Magnetics
• /
• 제12권4호
• /
• pp.133-136
• /
• 2007

We have carried out the study of magnetocaloric effect for as-quenched and annealed $Fe_{91-x}Y_xZr_9$ alloys. Samples were prepared by arc melting the high-purity elemental constituents under argon gas atmosphere and by single roller melt spinning. These alloys were annealed one hour at 773 K in vacuum chamber. The magnetization behaviours of the samples were measured by vibrating sample magnetometer. The Curie temperature increases with increasing Y concentration (x=0 to 8). Temperature dependence of the entropy variation ${\Delta}S_M$ was found to appear in the vicinity of the Curie temperature. The results show that annealed $Fe_{86}Y_5Zr_9$ and $Fe_{83}Y_8Zr_9$ alloys a bigger magnetocaloric effect than that those in as-quenched alloys. The value is 1.23 J/kg K for annealed $Fe_{86}Y_5Zr_9$ alloy and 0.89 J/kg K for as-quenched alloy, respectively. In addition, the values of ${\Delta}S_M$ for $Fe_{83}Y_8Zr_9$ alloy is 0.72 J/Kg K for as-quenched and 1.09 J/Kg K for annealed alloy, respectively.

• Environmental Engineering Research
• /
• 제25권3호
• /
• pp.426-438
• /
• 2020

In this study, cherry kernel shell pyrolytic charcoal was synthesized (CKSC) and composite beads were obtained by blending this pyrolytic charcoal with chitosan and Fe₂O₃ nanoparticles (Fe-C-CKSC). Cr(VI) adsorption from aqueous solutions by Fe-C-CKSC composite beads and CKSC adsorbents was studied comparatively. The effects of Cr(VI) initial concentration, adsorbent dosage, contact time, pH and temperature parameters on Cr(VI) adsorption were investigated. Adsorption reached an equilibrium point within 120 min for CKSC and Fe-C-CKSC adsorbents. The maximum Cr(VI) removal was obtained at the initial pH value of 1.56 for CKSC and 2.00 for Fe-C-CKSC. The optimum adsorbent dosage was found to be 5 g/L for CKSC and 3 g/L for Fe-C-CKSC. Based on the Langmuir model, the maximum adsorption capacities were calculated as 14.455 mg/g and 47.576 mg/g for CKSC and Fe-C-CKSC, respectively. Thermodynamic and kinetic studies were performed. As a result of adsorption kinetics calculations, adsorption was found to be consistent with the pseudo second order kinetic model. Characterization of the synthesized adsorbents was performed by SEM, BET, FTIR and elemental analysis. This study has shown that low cost adsorbents CKSC and Fe-C-CKSC can be used in Cr(VI) removal from aqueous solutions.