• Journal of Electrochemical Science and Technology
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• 제2권2호
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• pp.76-84
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• 2011

Potentiostatic oxidation of Pb-1.7%Sb alloy used in the manufacture of grids of lead-acid batteries over the potential range from -1.0V to 2.3V in 5M $H_2SO_4$ in the absence and the presence of 0.4M $H_3PO_4$ and the self-discharge characteristics of the oxide layer formed is studied by electrochemical impedance spectroscopy (EIS). Depending on the potential value, sharp variations in resistance and capacitance of the alloy are recorded during the oxidation and they can be used for identification of the various substances involved in passive layer. Addition of $H_3PO_4$ is found to deteriorate the insulating properties of the passive layer by the retardation of the formation of $PbSO_4$. $H_3PO_4$ completely inhibits the current and impedance fluctuations recorded in $H_3PO_4$-free solutions in the potential range 0.5 V-1.7 V. These fluctuations are attributed to the occurrence of competitive redox processes that involve the formation of $PbSO_4$, $PbOSO_4$, PbO and $PbO_2$ and the repeated formation and breakdown of the passive layer. Self-discharge experiments indicate that the amount of $PbO_2$ formed in the presence of $H_3PO_4$ is lesser than in the $H_3PO_4$-free solutions. The start of transformation of $PbSO_4$ into $PbO_2$ is greatly shortened. $H_3PO_4$ facilitates the diffusion process of soluble species through the passive layer ($PbSO_4$ and basic $PbSO_4$) but impedes the diffusion process through $PbO_2$.

• 한국세라믹학회지
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• 제30권7호
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• pp.543-548
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• 1993

Stability and formation of Pb(Mg1/3Nb2/3)O3 (PMN) phase synthesized in Li2SO4-Na2SO4 molten salts have been investigated. And powder characteristics of PMN have been studied with a variation of processing parameters such as temperature, time, amount of the salts, and excess PbO. More ratio of Li2SO4 to Na2SO4 influences the percentage of perovskite phase due to the difference of the eutectic point of the salts, but does not influence the powder characteristics. The shape of PMN particles shows faceted morphology with bimodal distribution consisting with large and submicron parts. Particle size of PMN increased greatly with increasing soaking time or amount of salts rather than temperature. The addition of excess PbO resulted in round PMN crystallites without submicron particles. These results are discussed by XRD, SEM and thermal analyses.

• 분석과학
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• 제17권5호
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• pp.369-374
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• 2004

플라스틱을 황산으로 탄화시키고 질산으로 산화 분해한 후 과잉의 황산과 질산을 증발 건조에 의해 제거한다. 이때 침전된 납화합물 ($PbSO_4$)의 $SO{_4}^{-2}$ 이온을 염산산성에서 HI에 의해 $H_2S$로 환원하여 휘발시킨 다음 납을 용해한후 AAS와 ICP로 측정하였다. PVC-Pb 표준시료 (690~34610mg/kg)를 이용하여 재현성 실험을 하였으며 예상농도에 대비하여 99.9% 이상의 정확성을 보였다. 정밀성은 AAS는 99.8%, ICP는 99.9%로 비슷하였다.

• 한국재료학회지
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• 제17권1호
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• pp.43-49
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• 2007

Electrochemical migration phenomenon is correlated with ionization of anode electrode, and ionization of anode metal has similar mechanism with corrosion phenomenon. In this work, in-situ water drop test and evaluation of corrosion characteristics for SnPb solder alloys in $Na_2SO_4$ solutions were carried out to understand the fundamental electrochemical migration characteristics and to correlate each other. It was revealed that electrochemical migration behavior of SnPb solder alloys was closely related to the corrosion characteristics, and Sn Ivas primarily ionized in ${SO_4}{^2-}$ solutions. The quality of passive film formed at film surface seems to be critical not only for corrosion resistance but also for electrochemical migration resistance of solder alloys.

• 대한화학회지
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• 제31권2호
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• pp.162-167
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• 1987

Monohydrogen arsenate를 전위차법으로 직접 정량하기 위하여 네가지 성분인 $Ag_2S$-PbS-$PbHAsO_4-Cu_2S$와 세가지 성분인 $Ag_2S$-PbS-$PbHAsO_4$로 된 전극이 제조되어 평가되었다. $Ag_2S$:PbS:$PbHAsO_4:Cu_2S$의 성분비(몰비)가 2.0:0.5:1.0:0.25인 전극이 전위차 감응, 안정도, 감응 속도와 재현성이 우수하였다. 0.1F $NH_4A_C-NH_4OH$ 완중용액 중의 일정한 이온 강도와 pH 8.50으로 조정된 $10^{-1}$~$10^{-4}M\;HA_SO_4^{2-}$ 농도 범위에서 실험하였고, $CN^-,\;I^-,\;S^{-2}$ 와 $Cl^-$등이 방해하였다.

• 한국가구학회지
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• 제19권3호
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• pp.211-218
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• 2008

This experiment was carried out to investigate the effect of internal holes on the bending strength of PB. The diameters of holes are 0mm to 13mm. The locations of holes are 1/8 to 4/5 point horizontally from sample end and are 1/5 to 4/5 vertically from sample surface, the numbers of holes are 1 to 4 pcs. In the size of internal holes, the bending strengths of PB were decreased significantly with the increase of diameter of holes, and the relationship between diameters(D) of holes and bending strength (${\sigma}_b$) of PB was ${\sigma}_b=-11D+168.8$ ($r^2=-0.99^{**}$). The effects of hole-locations and hole-numbers on the bending strengths of PB were large. and so they should be considered as major factors for the jointing design of PB.

• 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.

• Bulletin of the Korean Chemical Society
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• 제30권1호
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• pp.53-56
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• 2009

At room-temperature, a facile, seedless, and environmentally benign green route for the synthesis of star like PbS nanoclusters at 7 min in aqueous solution of 1-ethyl-3-methylimidazolium ethyl sulfate, [EMIM] [$EtSO_{4}$], room-temperature ionic liquid (RTIL), via ultrasonic irradiation is proposed. The X-ray diffraction studies display that the products are excellently crystallized in the form of cubic structure. An energy dispersive X-ray spectroscopy (EDX) investigation reveals the products are extremely pure. The absorption spectra of the product exhibit band gap energy of about 4.27 eV which shows an enormous blue shift of 3.86 eV that can be attributed to very small size of PbS nanoparticles produced and quantum confinement effect. A possible formation mechanism of the PbS nanoparticles using ultrasonic irradiation in aqueous solution of the RTIL is presented.

• 한국응용과학기술학회지
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• 제33권1호
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• pp.83-91
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• 2016

ISG (Idle Stop & Go) 시스템이 적용되는 자동차에 적합한 납축전지를 개발하기 위해 전극재료인 3BS ($3PbO{\cdot}PbSO_4{\cdot}H_2O$)와 4BS ($4PbO{\cdot}PbSO_4$)의 생성조건과 활물질의 화성 방법에 따른 납축전지 초기 성능과 심방전에 미치는 영향에 대해 연구 하였다. 양극과 음극 활물질을 숙성반응 중 온도 제어로 최종 생성 활물질의 상이 변하며, 납축전지의 수명에 영향을 미친다는 것을 알 수 있었다. 초기 성능에는 3BS 활물질을 적용한 AGM 납축전지와 Flooded 납축전지가 우수한 성능을 나타내는 반면 4BS 활물질을 적용한 AGM 납축전지는 상대적으로 낮은 성능을 나타내었다. 또한, 활물질 화성 효율을 비교분석하기 위해 화성을 3 step과 9 step으로 구분하여 시험한 결과, 3BS로 제작된 AGM 납축전지에 비해 4BS 활물질을 적용한 AGM 납축전지의 초기 성능이 우수 하였다. DOD17.5% 수명시험으로 수명성능을 비교한 결과, 잦은 심방전이 요구되는 ISG 시스템에서 Flooded 납축전지는 적합하지 않았으나, AGM 납축전지는 적합한 결과를 나타내었다. 결론적으로 AGM 납축전지가 ISG 시스템 적용 자동차에 적합하였고, AGM 납축전지의 숙성, 화성 방법에 따라 수명 성능이 80% 차이를 나타내는 것으로 확인되었다.

• 한국환경과학회지
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• 제11권4호
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• pp.361-366
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• 2002

Several effects on Pb$^{2+}$ removal by crab shell from aqueous solution were investigated. As the increase of initial Pb$^{2+}$ concentration and decrease of initial crab shell concentration, the time required to reach an equilibrium state and the residual Pb$^{2+}$ concentration increased. In our experimental ranges, the optimum initial Pb$^{2+}$ concentration and crab shell concentration were below 103 mg/$\ell$ and over 0.5 mg/$\ell$, respectively. Also, in order to investigate the mechanism of Pb$^{2+}$ removal by crab shell in aqueous solution, the crab shell was compared with chitosan and chitin on aspects of Pb$^{2+}$ removal capacity and Pb$^{2+}$ removal rate. The Pb$^{2+}$ removal by crab shell was greater than that by chitin and chitosan. The role of chitin was not so great in Pb$^{2+}$ removal by crab shell. The Pb$^{2+}$ removal by chitosan was not exactly correlated to the molecular weight of chitosan. weight of chitosan.