• Journal of the Mineralogical Society of Korea
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• v.8 no.2
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• pp.118-125
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• 1995

경북 구룡포에 소재한 구룡광산에서 산출하는 불석(클리놉틸로라이트와 모데나이트의 집합체)에 대한 Pb2+, Cd2+, Zn2+, Co2+, Fe2+ 및 NH4+ 등 양이온의 치환성질을 알아보기 위하여 베치실험을 실시하였다. 60∼80 메쉬 및 230 메쉬의 시료를 사용하여 각각 50ppm의 농도를 가진 용액과 반응시켰다. 반응후의 용액은 AA 및 전극 (NH4+)으로 분석하여 치환양을 측정하였다. 본 연구결과 Pb2+와 NH4+가 다른 이온들보다 훨씬 높은 선택성을 보여 주었다. 불석에 대한 이온들의 선택성은 NH4+, Pb2+》Zn2+, Cu2-, Co2->Cd2-, Fe2+와 같다. 실험결과 불석시료가 용액으로부터 흡착한 양이 시료로부터 용액으로 추출된 양보다 훨씬 높게 나타나고 있는 바 이는 이온치환보다는 불석의 시브(sieve) 효과에 의한 이온흡착현상이 우세하게 일어났다는 것을 지시해준다. 본 실험은 이 불석이 중금속과 암모니아와 같은 오염물을 제거하는데 사용될 수 있음을 보여준다.

• KSBB Journal
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• v.11 no.2
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• pp.173-180
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• 1996

The contamination of the environment by heavy metals results in a serious public health problem due to the toxicity of those pollutants even at low concentrations. Microorganisms may be used to remediate wastewaters contamlialtd with heavy metals. The waste S. cerevisiae is an inexpensive readily available source of biomass for bioremediation of wastewater. S. cerevisiae was investigated for their ability to absorb Pb. The crushed biomass of S. cerevisiae exhibited higher Pb uptake capacity than the living S. cerevisiae and the sterilized S. cerevisiae. At the same metal concentration, metal uptake per unit concentration or adsorbent decreased when the biomass concentration rises. The order of the biosorption capacity of the living S. cerevisiae was Pb>Cu>Cd=Co>Cr. When S. cerevisiae was pretreated with 0.1 M NaOH, Pb uptake was increased by 150 percent and 0.1 M HC1, 0.1 M $H_2S_O4$ solutions were efficient in the desorption of Pb. The sorption equilibrium of Pb ions can be described by the Freundlich and Langmuir models.

• Korean Chemical Engineering Research
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• v.45 no.2
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• pp.166-171
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• 2007

The adsorption behavior of $Pb^{2+}$ was compared between calcium alginate beads and capsules, which have different structures of alginate-gel core beads and liquid core alginate-membrane capsules, respectively. In terms of adsorption kinetics and isotherms, adsorption characteristics depending on pH and hardening time were compared for both adsorbents and also released calcium ion during the adsorption process was monitored. The adsorption of $Pb^{2+}$ on both adsorbents was caused by surface complexation and ion exchange mechanisms, both of which have similar effects on adsorption process regardless of the amount of adsorbed $Pb^{2+}$. The dependence of $Pb^{2+}$ adsorption upon pH was also similar for both adsorbents indicating the existence of similar functional groups on the surface of adsorbents. However, a different $Pb^{2+}$ adsorption behavior was observed considering the adsorption kinetics. The adsorption kinetic of $Pb^{2+}$ on alginate beads was slower than on alginate capsules and the maximum adsorption loading ($Q_{max}$) onto alginate beads was also less than onto alginate capsules by 49%. This drawback of alginate beads compared to capsules were ascribed to a diffusion limitation due to solid gel-core structure of alginate beads.

• Korean Journal of Microbiology
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• v.30 no.4
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• pp.310-315
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• 1992

Absorption of $\textrm{Pb}^{2-}$ from aqueous solution was studied using Staphylococcus epidermidis. Cells of exponential phase were employed as absorbents. Uptake ratio defined as the ratio of amount of $\textrm{Pb}^{2+}$ absorbed to that of initial $\textrm{Pb}^{2+}$. Absorption of $\textrm{Pb}^{2+}$ increased with increase in cell concentration. while amount of $\textrm{Pb}^{2+}$ per unit cell mass decreased. Uptake ratio of $\textrm{Pb}^{2+}$ augmented and then diminished after exhibiting a maximum as the pH of the solution increased. Equilibrium absorption of $\textrm{Pb}^{2+}$ deviated from Freundlich isotherm especially at higher concentration of $\textrm{Pb}^{2+}$ due to the precipitation phenomena. HCI and EDTA were founded to desorb $\textrm{Pb}^{2+}$ more effectively than $\textrm{Na}_{2}\textrm{CO}_{3}$ or $\textrm{NaHCO}_{3}$. After 10 cycles of absorption and desorption. $\textrm{Pb}^{2+}$ absorption capability remained almost unchanged and the biomass had leaked out 30-40 wt/%. Uptake ratio of Pb2+ decreased in the presence of other heavy metal ions due to the competitive absorption The inhibition of $\textrm{Pb}^{2+}$ absorption appeared to have a strong correlation with ionic radius of the competing ions. Especially $\textrm{Cr}^{3-}$, $\textrm{Co}^{2+}$ or $\textrm{Fe}^{2+}$ having smaller ionic radius depressed more significantly the uptake of $\textrm{Pb}^{2+}$ than any other metal ions tested.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.11
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• pp.1146-1152
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• 2005

Graft copolymers were synthesized from methylcellulose(MC) and acrylic acid(AA) with active carboxyl groups in the presence of potassium persulfate($K_2S_2O_8$) initiator to enhance adsorption capacity of toxic heavy metal such as $Pb^{2+}$ and $Cu^{2+}$ from wastewater. The resulting grafted copolymers(MC-g-AA/PAA) were mixture of the graft copolymers from MC and AA(MC-g-AA) and polyacrylic acid homopolymers(PAA). The degree of palling was increased with rising concentration of monomer and initiator under the reaction conditions at $60^{\circ}C$, 3 hrs. The water insoluble property of MC-g-AA showed more than 19.7% degree of grafting. So that it could be an adsorbent of heavy metals. Adsorption characteristics of the MC-g-AA were evaluated depending on the degree of grading, pH of wastewater, adsorption time, dosage of MC-g-AA and concentration of heavy metals in the different conditions. Degree of grafting, and initial concentration of heavy metal ions increased, the adsorption amount of $Pb^{2+}$ and $Cu^{2+}$ increased, but added MC-g-AA increased, the adsorption amount per unit weight of $Pb^{2+}$ and $Cu^{2+}$ decreased. The MC-g-AA showed the high $Pb^{2+}$ and $Cu^{2+}$ adsorption amount in the range pH $4{\sim}6$. Also all of $Pb^{2+}$ and $Cu^{2+}$ ions reached in adsorption equilibrium in neighborhood 4 hours. The adsorption of heavy metals described by Freundlich isotherm, it was determined the value of l/n of $Pb^{2+}$ and $Cu^{2+}$ that 0.4294 and 0.3453, respectively.

• Korean Journal of Materials Research
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• v.6 no.12
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• pp.1155-1161
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• 1996

Pb(In1/2Nb1/2)O3 (PIN)세라믹스에서 Pb+2이온 대신에 Ca+2, Sr+2, Ba+2 이온을 부분적으로 치환하여 상합성 과정 및 유전특성을 조사하였다. 페로브스카이트 PIN을 얻기위한 최적조건을 도출하기위하여 하소, 치환 이온의 종류 및 그량, 소결민돌, 유전특성의 관점에서 관찰하였다. 페로브로스카이트 PIN상을 합성하기 위해서는 Ba+2이온의 치환이 가장 효과적이었다.

• Journal of the Korean Chemical Society
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• v.40 no.9
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• pp.607-614
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• 1996

The structural changes and dielectric properties of Pb1-x(Na1/2La1/2)x(Mg1/3Nb2/3)O3 compounds substituted by 0∼50 mol.% of Na+/La3+ mixed ions were investigated by X-ray diffraction method, IR and Raman spectroscopy, and LCR meter. The amount of perovskite phase increased with the increases of Na+/La3+ substituents and sintering temperatures. Although the superlattice lines due to 1:1 ordering were not detected by X-ray diffraction method, it was found, from the Raman spectroscopy and the increase of diffuseness coefficient, that the ordering behavior was related to the decrease of A site ion size. Dielectric properties in Pb1-x(Na1/2La1/2)x(Mg1/3Nb2/3)O3 were affected by the amount of perovskite phase, grain size, and density. The phase transitions were broadened and phase transition temperatures were lowered by the increase of Na+/La3+ ions.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.59.1-59.1
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• 2009

레독스 흐름 배터리 (Redox Flow Battery)는 외부의 탱크 등에 저장해 둔 활성물질(이온 가수가 변화는 금속) 의 용액을 펌프로 전해셀에 공급하여 충전 방전하는 배터리로 신재생 에너지인 풍력과 태양광 발전, 야간의 잉여 전력 저장 등 대용량 전력 저장 장치로 관심이 높아지고 있다. 대표적인 레독스 흐름 배터리로 알려진 바나듐 레독스 흐름 배터리는 이온 교환막 사용으로 인하여 전기전도도, 기계적 강도, 투과도 및 전해질 내의 화학적 안정성 등 여러 가지 문제점과 함께 비용 문제점을 야기한다. 하지만 새로운 용해 납 레독스 흐름 배터리는 이온 교환막을 사용하지 않아 바나듐 레독스 흐름 배터리의 문제점 및 시설비가 절약되는 장점이 있어 새로이 연구되지고 있다. 본 연구는 레독스 흐름 배터리에 주로 이용되는 카본 전극재료의 따라 형성되는 Pb, $PbO_2$ 박막의 미세 구조를 및 에너지 효율 특성을 분석하였다. 실험은 half-cell로 이루어졌으며 작업전극은 Carbon felt, Ordered Graphite, Disordered Graphite, Glassy Carbon 등을 여러 카본 재료를 사용하였고, 상대전극은 Pt, 기준전극으로 Ag/AgCl를 사용하여 Cyclic Voltammetry특성과 충방전 특성을 연구하였다. 전해질은 Lead Carbonate ($PbCO_3$)+Methanesulfonic acid ($CH_3SO_3H$) 들어간 수용성 전해질을 교반을 통해 이용하였다. 여러 carbon 전극재료와 생성된 Pb, $PbO_2$ 막의 표면구조, 미세구조, 상들의 변화는 XRD, SEM, EDX, Raman등을 통하여 분석하였으며, 전기화학 공정의 변수와 전극에 따른 에너지 효율특성에 대하여 고찰해 보았다.

• The Korean Journal of Zoology
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• v.23 no.3
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• pp.137-148
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• 1980

The effects of divalent cations, $Hg^{2+}, Cu^{2+}, Pb^{2+}, Cd^{2+}$, and $Mn^{2+}$ on the total ATPase activity of the fragmented sarcoplasmic reticulum isolated from rabbit skeletal muscle were investigated. The inhibitory effects of the cations on the enzyme activity increased as the concentrations of the ions increased with the order of efficiency of $Hg^{2+}$ > $Cu^{2+}$ > $Pb^{2+}$ > $Cd^{2+}$ > $Mn^{2+}$ in the concentration range between 10 and 500$\mu$M. The 50% inhibition for each ion was almost identical with the inhibition constant (Ki) value for each ion. The Ki's were 10, 30 130, and 350$\mu$M for $Hg^{2+}, Cu^{2+}, Pb^{2+}, and Cd^{2+}$, respectively. $Mn^{2+}$ seemed to be an activator at lower concentrations and an inhibitor at higher concentrations. The presence of the cations did not change the Km values, suggesting that the ions act as a reversible noncompetitive inhibitor on the FSR ATPase. The energy of activation of the enzyme was aproximately 19 Kcal/mole. The presence of the ions decreased the value slightly. A possible mechanism for the reversible noncompetitive inhibitory effect of the cations was discussed.

• Journal of the Korean Chemical Society
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• v.44 no.2
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• pp.115-119
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• 2000

A PVC membrane electrode based on upper-rim calix[4] crown as ionophore was prepared using dioctyl sebacate (DOS) as a plasticizer. The potential response of this membrane electrode to alkali, alka-line earth and transitionmetal metal cations were examined. This membrane electrode exhibited a Nernstian response to $10^{-6}{\sim}10^{-2}M\;Pb(NO_3)_2$ with a slope ot 27.0 mV/decade. Its response time ($t_{90}$) was 10s and it could be used for at least 2 months. Also, the potential was maintained constantly in the rage of ph $2.0{\sim}12$.