• 한국세라믹학회지
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• 제33권7호
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• pp.743-754
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• 1996

In this study (Ba1-xPbx)TiO3 was synthesized by modified oxalate process in order to prevent vaporization of PbO through low temperature synthesis climinate Cl ion reproducibly substitute Pb for by and uniformly distribute ion (Ba1-xPbx)TiO3 was synthesized by coprecipitation of lead acetate barium acetate and ammonium titanyl oxalate have been used as starting materials. The substitution of Pb for Ba was reproducibly possible synthetic temperature of perovskite structure becomes lowed as the Pb concentration increases and fine partic-les (specific surface are :7.2 cm2/g) were obtained, BaTiO3 powders calcined at 90$0^{\circ}C$ for 3 hours were cubic from in XRD analysis and as Pb content was increases evident split of tetragonal peaks could be observed The optimum conditions to synthesize (Ba,Pb)TiO3 powder are the followings ; synthesis temperature (5$^{\circ}C$)

• Environmental Engineering Research
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• 제9권6호
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• pp.299-307
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• 2004

• Membrane and Water Treatment
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• 제11권1호
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• pp.41-48
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• 2020

Lead is a highly toxic heavy metal that causes serious health problems. Nonetheless, it is increasingly being used for industrial applications and is often discharged into the environment without adequate purification. In this study, Pb(II) was removed by powdered waste sludge (PWS) based on the biosorption mechanism. Different PWSs were collected from a submerged moving media intermittent aeration reactor (SMMIAR) and modified Ludzack-Ettinger (MLE) processes. The contents of extracellular polymeric substances were similar, but the surface area of MLE-PWS (2.07 ㎡/g) was higher than that of SMMIAR-PWS (0.82 ㎡/g); this is expected to be the main parameter determining Pb(II) biosorption capacity. The Bacillaceae family was dominant in both PWSs and may serve as the major responsible bacterial group for Pb(II) biosorption. Pb(II) biosorption using PWS was evaluated for reaction time, salinity effect, and isotherm equilibrium. For all experiments, MLE-PWS showed higher removal efficiency. At a fixed initial Pb(II) concentration of 20 mg/L and a reaction time of 180 minutes, the biosorption capacities (q_e) for SMMIAR- and MLE-PWSs were 2.86 and 3.07 mg/g, respectively. Pb(II) biosorption using PWS was rapid; over 80% of the maximum biosorption capacity was achieved within 10 minutes. Interestingly, MLE-PWS showed enhanced Pb(II) biosorption with salinity values of up to 30 g NaCl/L. Linear regression of the Freundlich isotherm revealed high regression coefficients (R² > 0.968). The fundamental Pb(II) biosorption capacity, represented by the K_F value, was consistently higher for MLE-PWS than SMMIAR-PWS.

• Bulletin of the Korean Chemical Society
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• 제30권5호
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• pp.1135-1138
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• 2009

Hollow Sn and Pb nanoparticles have been prepared by a rapid injection of an aqueous solution of $SnCl_2$- poly(vinylpyrrolidone) (PVP, surfactant) and $Pb(OAc)_2${\cdot}$3H_2O-PVP$ into an aqueous solution of sodium borohydride (reducing agent) in simple, one-pot reaction at room temperature under an argon atmosphere, respectively. The two hollow nanoparticles have been fully characterized by TEM, HRTEM, SAED, XRD, and EDX analyses. Upon exposure to air, the black Pb hollow nanoparticles are gradually transformed into a mixture of Pb, litharge (tetragonal PbO), massicot (orthorhombic PbO), and $Pb_5O_8$. The order and speed of mixing of the reactants between the metal precursor-PVP and the reductant solutions and stoichiometry of all the reactants are crucial factors for the formation of the two hollow nanocrystals. The Sn and Pb hollow nanoparticles were produced only when 1:(1.5-2) and 1:3 ratios of the Sn and Pb precursors to $NaBH_4$ were employed with a rapid injection, respectively.

• 분석과학
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• 제33권6호
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• pp.245-251
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• 2020

납은 암석의 연대측정, 지각의 진화 및 오염원의 기원 추적과 같은 지구화학적 연구에 유용하게 사용되어지는 원소로, 이를 위해선 고순도 원소 분리가 선행되어져야한다. 본 연구에서는 납을 분리해 내는데 있어서 용리액의 농도가 6M HCl 과 8M HCl 중 어느 것이 더 효율적인지 비교 검토 하였다. 그 결과, 6M HCl의 경우 8M HCl 보다 용리액을 다량으로 사용했음에도 불구하고 납 분리에 있어서는 효율적이지 않았다. 그리고 납 분리법에 대한 신뢰성 검증을 위하여 납 동위원소 표준물질(NIST NBS981)과 암석표준시료(BCR-2, GSP-2, JG-1a)의 납 동위원소비를 열이온화질량분석기로 측정한 결과, 기존 보고 값과 오차 범위 내에서 잘 일치하였다.

• Nuclear Engineering and Technology
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• 제53권12호
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• pp.4130-4136
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• 2021

By polymerization of gadolinium methacrylate (Gd (MAA)₃), lead methacrylate (Pb(MAA)₂) and methyl methacrylate (MMA), Gd and Pb were chemically bonded into polymers. The X-ray shielding performance was evaluated by Monte Carlo simulation method, and the results showed that the more metal functional organic monomer, the better the shielding performance of terpolymers. When the X-ray energy is 65 keV, Gd (MAA)₃-containing polymers have better shielding performance than Pb(MAA)₂-containing polymers. Gd could compensate for the weak absorption region of Pb. Therefore, polymers containing both Gd and Pb enhanced shielding efficiency against X-ray in various low-energy ranges. For obtaining terpolymers with uniform monomer compositions, the relationship between the monomer composition of the terpolymers and the conversion level was optimized by calculating the reactivity ratios. The value of reactivity ratios of r (Gd (MAA)₃/Pb(MAA)₂), r (Pb(MAA)₂/Gd (MAA)₃), r (Gd (MAA)₃/MMA), r (MMA/Gd (MAA)₃), r (Pb(MAA)₂/MMA) and r (MMA/Pb(MAA)₂) was 0.483, 0.004, 0.338, 2.508, 0.255, 0.029. The terpolymers with uniform monomer composition could be obtained by controlling the monomer compositions or conversion levels. The results can provide new radiation protection materials and contribute to the improvement in nuclear safety.

• The Korean Journal of Ecology
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• 제21권3호
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• pp.179-186
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• 1998

Effects of lead(Pb) and calcium(Ca) on growth responses, accumulation of heavy metals and nitrogen fixation activities of Melilotus suaveolens seedlings were quantitatively analyzed during growing period. Pb contents of the root treated with 30, 100 ppm Pb and 100 ppm Pb added 100 ppm Ca were 54.1, 90.9 and 26.1 folds higher than that of the control, respectively, at pH 4.2 in 28th days, and heavy metal content of plant increased with increasing of pH and Pb concentration. The melilot plant was classified as a Pb accumulator by higher accumulation of Pb in shoot than that of root. Pb treatments resulted in inhibiton of height and chlorophyll contet, and Ca treatment increased height and chlorophyll content insignificantly at pH 4.2 in 28 days. The plant biomass reduced 49, 60 and 54% at pH 4.2 and 47,53 and 50% at pH 6.5, respectively, by 30, 100 ppm Pb and 100 ppm Pb added 100 ppm Ca treatment. Specific nitrogen fixation of nodules reduced 68.4% and 46.6% by 100 ppm Pb treatment and 3.7% and 24.9% by 100 ppm Pb added 100 ppm Ca at pH 4.2 and pH 6.5, respectively, so Ca inhibited significantly Pb activity and toxicity in acdic pH. Nodule formation were reduced to 33, 33 and 50% at pH 4.2 and 50, 33 and 38% at pH 6.5 by 30, 100 ppm Pb and 100 ppm Pb added 100 ppm Ca, respectively.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.915-920
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• 2001

A spent fuel problem has prevented the nuclear power from claiming to be a completely clean energy source. The nuclear transmutation technology to incinerate the long lived radioactive nuclides and produce energy during the incineration process is believed to be one or the best solutions. HYPER(Hybrid Power Extraction Reactor) is the accelerator driven transmutation system which is being developed by KAERI(Korea Atomic Energy Research Institute). Some major feature of HYPER have been developed and employed. On-power fueling concepts are employed to keep system power constant with minimum variation of accelerator power. A hollow cylinder-type metal fuel is designed for the on-line refueling concept. Lead-bismuth(Pb-Bi) is adopted as a coolant and Spallation target material. HYPER is a subcritical reactor which needs an external neutron source. 1GeV proton beam is irradiated to Lead-bismuth(Pb-Bi) target inside HYPER, and spallation neutrons are produced. When proton beams are irradiated, much heat is also deposited in the Pb-Bi target and beam window which separates Pb-Bi and accelerator vacuum. Therfore, an effective cooling is needed for HYPER target. In this paper, we performed the thermal-hydraulic analysis of HYPER target using FLUENT code, and also calculated thermal and mechanical stress of the beam window using ANSYS code.

• Membrane and Water Treatment
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• 제6권5호
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• pp.393-409
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• 2015

Zinc and lead pollution are public environmental issues that have attracted lots of attention for a long time. Landfill leachate contains heavy metals, such as Zn(II) and Pb(II), which are usually related to the pollution of groundwater, especially in developing countries. Bentonite has been proven to be effective in enhancing the membrane property of clay, by which landfill liners can have better barrier performance towards the migration of contaminants. In this study, 5% sodium bentonite amended with locally available Fukakusa clay was utilized to evaluate the membrane behavior towards the heavy metals zinc and lead. The chemico-osmotic efficiency coefficient, ${\omega}$, was obtained through Zn(II) and Pb(II) solutions with different concentrations of 0.5, 1, 5, 10, and 50 mM. According to the results, ${\omega}$ continually decreased as the Zn(II) and Pb(II) concentrations increased, which is consistent with the Gouy-Chapman theory. Compared to normal inorganic ions, the membrane behavior towards heavy metal ions was lower. The migration of heavy metal ions was not observed based on experimental results, which can be attributed to the adsorption or ion exchange reaction. The mechanisms of the membrane performance change were discussed with the assistance of XRD patterns, free swelling results, XRF results, and SEM images.

• 한국환경보건학회지
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• 제12권2호
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• pp.17-26
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• 1986

Earlier studies have shown that the administration of Na-alginate, a water-soluble, non absorbable acidic polysaccharide, effectively reduces the absorption of radioactive strontium, cadmium and other bivalent metals. In this study the effects of Na-alginate on the Toxicity induced by Lead and Cadmium were examined in rats and the following results were obtained. 1. The elevations of the activities of serum GOT, GPT by Pb and Cd administration in the experimental animals. However, the administration of Na-alginate significantly inhibited the elevation of serum GOT, GPT. 2. Generally serum TBA values were significantly elevated in Pb and Cd group in comparison with the control group. However, the administration of Na-alginate inhibited the elevation of serum TBA values. 3. The activity of Alkaline phosphatase was also significantly elevated in Cd group in comparison with the control group. However, the administration of Na-alginate significantly inhibited the elevation of serum alkaline phsphatase. 4. Furthermore, the activity of $\delta$-aminolevulinic acid dehydratase in red blood cells was also significantly inhibited by Pb and this inhibition was stimulated by the administration of Na-alginate. 5. The concentrations of Pb in liver and Cd in kidney were markedly increased by Pb and Cd. However, the administration of Na-alginate significantly inhibited the elevation of them.