• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.1
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• pp.3-10
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• 2016

Effects of acid ($HNO_3$ and HCl) modification on the adsorption properties of Pb(II) and Cu(II) onto bamboo-based activated carbon (BAC) were investigated through a series of batch experiments. The carbon content increased and oxygen content decreased with acid treatment. $HNO_3$ induced carboxylic acids and hydroxyl functional groups while HCl added no functional group onto BAC. The pseudo-second order model better described the kinetics of Pb(II) and Cu(II) adsorption onto experimented adsorbents, indicating that the rate-limiting step of the heavy metal sorption is chemical sorption involving valency forces through sharing or exchange of electrons between the adsorbate and the adsorbent. The equilibrium sorption data followed both Langmuir and Freundlich isotherm models. The adsorption capacities of BAC were affected by the surface functional groups added by acid modification. The adsorption capacities were enhanced up to 36.0% and 27.3% for Pb(II) and Cu(II), respectively by the $HNO_3$ modification, however, negligibly affected by HCl.

• Journal of the Korean Ceramic Society
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• v.12 no.2
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• pp.3-9
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• 1975

The continuous grading method of pyrophyllite particles was adopted to prepare the refractories for ladle. The optimum conditions of fabrication adjusting the binders, the amount of water, the forming pressure and the firing temperature were investigated. The various properties, such as strength, density, porosity, thermal shock, corrosion resistance to slag were measured and compared with properties of ladle bricks presently used at local steel plants. The specimen studied in the present investigation showed a rather superior properties to theconventional product available locally.

• Journal of environmental and Sanitary engineering
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• v.22 no.3
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• pp.1-12
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• 2007

This study was investigated hazardous substances in agricultural products of baggage by Incheon Port from chinese. We tested 293 kinds of dried red pepper, cereal, sesame, bean, nut, herbal medicine and sesame oil for pesticides residue, mold, tar color, sudan I, II, III, IV, aflatoxin, Pb, Cd, Hg, As and sulfur dioxide residues. Violated samples over standard limits by Korean Food and Drug Administration (KFDA) were 76 dried red pepper over the number of mold and 1 dried red pepper detected red 102 tar color and 1 dried red pepper over the number of mold and detected red 102 tar color simultaneously. And 2 rice, 1 sticky rice, 1 adlay and 1 millet were over lead. Violated herbal medicine were 2 Zizyphi Furctus and 2 Zingiberis Rhizoma over sulfur dioxide residue and 1 Zingiberis Rhizoma over sulfur dioxide residue and cadmium simultaneously. The contents of heavy metals in cereal were as follow; $Pb\;0.000{\sim}0.740mg/kg(0.191{\pm}0.209),\;Cd\;0.000{\sim}0.108mg/kg(0.007{\pm}0.020),\;Hg\;0.000{\sim}4.201mg/kg(0.162{\pm}0.319)$. The contents of heavy metals in herbal medicine were as follow; $Pb\;0.000{\sim}2.480mg/kg(1.130{\pm}0.730),\;Cd\;0.000{\sim}0.761mg/kg(0.044{\pm}0.122),\;Hg\;0.000{\sim}0.157mg/kg(0.022{\pm}0.033),\;As\;0.000{\sim}0.560mg/kg(0.040{\pm}0.082)$. Contents of $SO_2$ ranged $2.0{\sim}1459.4ppm(303.1{\pm}324.2)$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.3
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• pp.169-175
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• 1976

A solvent extraction-atomic absorption spectrophotometry for determination of trace amount of cadmium, copper, lead and zinc and a flameless atomic absorption spectrophotometry for mercury in sea water were studied. The optimum pH range for solvent extraction was pH 4-7. A better solvent extraction efficiency was obtained with MIBK solvent than nitrobenzene, benzene, isoamylalcohol, n-buthylacetate. DDTC was more advantageous than APDC as chelating agent. The metals, chelated with DDTC and concentrated into MIBK by solvent extraction with a volume of $1\iota$ of sea water for cadmium, copper and lead, and 200m1 for zinc, were determined simultaneously by atomic absorption spectrophotometry. For mercury determination, 500ml of sea water was digested with permanganate-sulfuric acid and mercury( II ) was reduced by stannous chloride and aerated the solution with air pump until the absorbance reached a constant value. The precisions, in standard deviation, of these methods were 0.058ppb for cadmium, 0.084 ppb for copper, 0.44ppb for lead, 2.49ppb for zinc and 0.08 ppb for mercury. The sensitivities, expressed in $ppb/1\%$ absorption, were 0.058 ppb cadmium, 0. 15 ppb copper, 0.6 ppb lead, 1.2 ppb zinc and 0.01 ppb mercury respectively. No significant adsorption on the wall of polyethylene sample bottle occurred during 30 days of storing by acidification to pH 1.5 with nitric acid except zinc. Poor reproducibility was found for zinc with this method.

• Analytical Science and Technology
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• v.5 no.4
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• pp.417-423
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• 1992

The effects of metal ions on the arsenic(III) stripping peak were examined by the cathodic stripping voltammetry. The reduction stripping peak potential and current of arsenic(III) value were -0.79V(vs. Ag/AgCl). $0.86{\mu}A$ by using 0.1N-hydrochloric acid solution. When 10 times of Cu(II) was added to the solution, the reduction stripping peak potential of arsenic(III) was the value of -0.84V(vs. Ag/Cl), which showed a good agreement with theoretical value -0.84V(vs. Ag/Cl) by using 0.1N hydrochloric acid solution. Lead(II) and copper(II) increased the stripping peak heigh of arsenic(III), Among them, the copper(II) extremely enhanced it.

• 한국문화재보존과학회:학술대회논문집
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• 2004.10a
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• pp.72-74
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• 2004

The color change of lead-containing pigments is one of the most serious diseases in watercolor, oil paintings and wall paintings. These pigments have a tendency to darken or brighten. It was proved that oxidation of lead containing pigments in the formation of brown-colored lead dioxide is a photochemical reaction under high humidity conditions. Therefore, we carried out some analogic experiments on the color change of three typical lead containing pigments ; $Pb_3O_4$, Pbo and $PbCo_3{\cdot}Pb(OH)_2$ at the conditions of illuminations under the high humidity ($2PbCo_3{\cdot}Pb(OH)_2$ R. H.). The reason for the chemical reactions are discussed and the results of these experiments are shown in some spectrograms, micrographs and X-ray micro-diffraction patterns. Important conclusions were drawn in our research. Due to the formation of brown $PbO_2$, red lead $(Pb_3O_4)$ and massicot (PbO) turned brown or dark when they were illuminated light under high humidity. We noticed that the brightening of red lead occurred d to admixture with chalk or lead white in egg yolk or linseed oil medium on exposure to light. Lead white used in oil paintings turned yellowish on dark.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.2
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• pp.33-41
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• 2018

Large amounts of leaves from street trees fall onto the streets annually and need to be cleaned and treated. Cherry trees are common street trees in Korea. The adsorption characteristics of Pb(II) by cherry leaf (CL) and cherry leaf-derived biochar (CB) were studied through a series of batch experiments. CB was produced through the carbonization of CL at $800^{\circ}C$ for 90 min. Carbonization increased the C content and pH value, while decreased H and O contents. Well developed pore structure was observed at the surface of CB. The pseudo-second order model better described the kinetics of Pb(II) adsorption onto CL and CB, indicating that the rate-limiting step of the heavy metal sorption is chemical sorption. Fast adsorption rates and high adsorption capacities were obtained by the carbonization from CL to CB. Langmuir models better adequately described the Pb(II) adsorption onto CL and CB. Maximum adsorption capacities of Pb(II) expressed by Langmuir constant, $Q^0$ were 37.31 mg/g and 94.34 mg/g, when CL and CB were used as adsorbents, respectively.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.429-436
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• 2005

In this study, we made two types of main control room floor systems (Type I, Type II) and several shaking table tests with and without isolation system were conducted to evaluate floor isolation effectiveness of LRB(Lead Rubber Bearing). Both type showed large difference according to input earthquake signals, but showed little difference according to floor type. It is required to make LRB of which design frequency is below 1Hz when applied to main control room of NPP, but considering much difficulties in making such LRB, it is recommended that consideration should be taken into account when applied to main control room of NPP.

• Journal of Technologic Dentistry
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• v.6 no.1
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• pp.11-14
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• 1984

The auther performed this experimental study on cervical margin distortion in preheating method during soldering. 1. In soldering methods, the method using the furnace has less distortion than the method using open-flame and longer the bridge spon, the larger the distortions. 2. Table Ⅰ Showed that buccal margin, lingual margin, mesial margin and distal margin had respectively 0.01mm, 0.02mm, 0.03mm, 0.03mm closer adaptation in 3 unit bridge than in 5 unit bridges. 3. Table II showed that buccal margin, lingual margin, mesial margin and distal margin had respectively 0.06mm, 0.07mm, 0.11mm, 0.05mm closer adaptation in 3 unit bridge than in 5 unit bridges.

• Journal of the Korean Chemical Society
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• v.41 no.6
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• pp.292-298
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• 1997

An ICP(Inductively Coupled Plasma) emission spectrometer was developed with an axially viewed ICP source incorporated by a 5-turned induction coil and a torch, outer quartz tube of which was 50 mm longer than that used in conventional ICP/AES(Inductively Coupled Plasma Atomic Emission Spectrometry). The Optimization of the system has been performed in terms of the determination of signal-to-noise ratio and background intensity at various rf powers, sample flow rates, argon gas flow rates and cut-off gas flow rates. The spectro-analytical characteristics of the spectrum obtained between 200 and 500 nm was revealed to be similar compared with a vertically viewed ICP source. The detection limit of Pb(Ⅱ) at 220.35 nm was 11 ppb which was 5 times lower than that obtained with a vertically viewed ICP source.