• The Korean Journal of Ecology
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• 제15권2호
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• pp.137-145
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• 1992

When exposed to 1, 700 ml of 0.089, 0.445 or 0.890 mM/l cadmius solution, dock (rumex crispus L)plants from heavily polluted chungrangchon site absorbed 0.0404, 0.2244 or 0.4929 mM of cadmium per g dw during the first 4 hours, which were 5.0~30.8 times faster uptake rate than those of water hyacinth (eichhornia crassipes Solm. - laub). Zinc, with which cadmium generally occurs together, did not affect the uptake rate in the concentration range of 0.0306 ~0.0918 mM/l. rumex cripus from chungrangchon site and from less polluted shingalchon site, when exposed to 1, 700 ml of 0.089 mM/l solution for 3 days, removed 68.4% and 63.2%, repectively, of the cadmium initially present in the solution. And when exposed to cadmium solution of the same concentration for the second time after cadmium-free hydroponic culture for three days, these plants removed 76.1% and 66.8% of cadmium, respectively. These removal rates were not significantly different between collection sites or between exposures, but were about 2 times greater for the first exposure, and 2~5 times greater for the second exposure, than those of water hyacinth. these results incate that rumex cripus can absorb, and thus remove, large amount of cadmium ion in wastewater, and so can be used in wastewater treatment, e.g. soil trench method. since there was large difference among the plants in the ability to absorb cadmium, it should be possible to select for strain with greater ability.

• 멤브레인
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• 제15권4호
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• pp.355-362
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• 2005

본 연구는 연료전지에 적용 가능한 술폰화된 고분자 이온교환막 개발에 관한 것으로, perfluorocyclobutane ring(PFCB)을 함유한 4,4'-biphenylene perfluorocyclobutyl ether 고분자를 합성하여 이를 술폰화제인 chlorosulfonic acid (CSA)와 용매인 dichloromethane (DCC) 혼합용액을 사용하여 후술폰화시킴으로써 PFCB기를 함유한 술폰화된 biphenylene 고분자 막을 제조하였다. 술폰화된 고분자의 제조시 biphenylene perfluorocyclobutyl ether 고분자와 CSA의 몰비를 각각 1:1, 1:2, 1:3, 1:4로 변화시켜주어 다양한 술폰산기의 함량을 갖는 이온교환막을 제조할 수 있었다. 합성된 화합물과 고분자는 NMR과 GPC를 통해서 분석 및 확인하였고, 술폰화된 막을 이용하여 술폰산기의 함량 변화에 따른 술폰화도, 이온교환용량, 함수율, 이온전도도 등을 측정하였다. 측정 결과, 술폰화도가 증가함에 따라 이온전도도, 이온교환용량 및 함수율이 연속적으로 증가하는 것을 확인할 수 있었다.

• 멤브레인
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• 제29권5호
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• pp.252-262
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• 2019

서로 다른 술폰화 정도에 따라 sulfonated star branched poly(styrene-b-butadiene-b-styrene) triblock copolymer (SSBS)가 합성되었다. 술폰화된 butadiene block은 FT-IR spectroscopy로 확인할 수 있다. 술폰화 정도를 측정 비교하기 위해서 산-염기 적정을 통하여, ion exchange capacity (IEC)를 계산하였다. 술폰화된 SSEB 전해질막은 높은 water uptake와 proton conductivity를 보였다. 실온에서 25 mol% 술폰화된 SSBS는 0.114 S/cm라는 높은 값을 나타냈으며, 이는 Nafion과 비슷한 수치였다. 일정한 상대 습도에서 온도의 증가는 현저하게 높은 수소이온전도도를 나타냄을 알 수 있었다. 모든 술폰화된 막은 Nafion과 비교했을 때 낮은 methanol 투과도를 보여주었다. AFM을 이용하여 술폰화된 전해질막의 구조는 이른바 분리된 나노구조의 미세상과 ionic channel의 접속으로 이루어졌음을 확인할 수 있었다.

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.627-636
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• 2022

In nuclear power plants and other nuclear facilities the removal of cobalt from radioactive liquid waste is needed to reduce the radioactivity concentration in effluents. In liquid wastes containing strong organic complexing agents such as EDTA cobalt removal can be problematic due to the high stability of the Co-EDTA complex. In this study, the removal of cobalt from NaNO₃ solutions using antimony oxide (Sb₂O₃) synthesized from potassium hexahydroxoantimonate was investigated in the absence and presence of EDTA. The uptake studies on the ion exchange material were conducted both in the dark (absence of UV-light) and under UV-C irradiation. Ca²⁺ or Ni²⁺ were included in the experiments as competing cations to test the selectivity of the ion exchanger. Results show that UV-C irradiation noticeably enhances the cobalt sorption efficiency on the antimony oxide. It was shown that nickel decreased the sorption of cobalt to a higher extent than calcium. Finally, the sorption data collected for Co²⁺ on antimony oxide was modeled using six different isotherm models. The Sips model was found to be the most suitable model to describe the sorption process. The Dubinin-Radushkevich model was further used to calculate the adsorption energy, which was found to be 6.2 kJ mol^-1.

• Journal of Ecology and Environment
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• 제34권3호
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• pp.279-286
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• 2011

The effect of allelochemicals on growth, root nodule nitrogen fixation activity, and ion patterns of soybeans were investigated. We prepared 50 g/L (T50), 100 g/L (T100), and 200 g/L (T200) extract concentrations by soaking fresh red pine needles in a nutrient solution. Adding needles to the nutrient solution increased the content of total phenolic acids, osmolality, and total ions. The total phenolic content in the T50, T100, and T200 extracts were $206{\pm}12.61$, $335{\pm}24.16$, and $603{\pm}12.30$ mg gallic acid equivalents, respectively. The $K^+$, $Mg^{2+}$, $Ca^{2+}$, and $PO_4^{3-}$ content increased by adding needles to the nutrient solutions, whereas $SO_4^{2-}$ content decreased. The growth inhibition of soybeans was proportional to the needle extract concentrations, and the T100 and T200 concentrations resulted in remarkable growth inhibition. On day 20 after treatment, dry weight and nitrogen fixation activity of the root nodules were reduced by the T100 and T200 treatments, whereas the T50 treatment was not difference from the control. After day 10, total ion content in all treatment groups was not different in comparison with the control. However, total ionic content in all treatment groups decreased significantly compared with that in the control after day 20. The lowest total ion value was found for the T200 concentration. The T200 treatment also resulted in significantly reduced $SO_4^{2-}$ content. The amounts of $Mg^{2+}$, $Ca^{2+}$, and $Mn^{2+}$ were higher than those of the control for the T50 treatment on day 10 and for T100 on day 20 after treatment. A significant increase in osmolality was observed in the T200 treatment on day 10 and in the T100 treatment on day 20. These results suggest that under severe allelochemical stress conditions, a remarkable reduction in nodule formation, nitrogen fixation activity, and ion uptake eventually resulted in a decrease in leaf production. Furthermore, increased $K^+$, $Mg^{2+}$, $Ca^{2+}$, $Mn^{2+}$, and osmolality in soybeans exposed to lower concentrations of allelochemicals than the critical stress level helped overcome the stress.

• 멤브레인
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• 제25권5호
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• pp.406-414
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• 2015

본 연구에서는 막 축전식 탈이온 공정에 적용하기 위해 온도와 시간을 달리하여 술폰화 Poly(VDF-co-hexafluoropropylene) copolymers (PVDF-co-HFP)을 합성 후 캐스팅법에 의해 양이온교환막이 제조되었다. 술폰화 PVDF (SPVDF)는 Fourier-transform infrared (FT-IR), $^1H$ Nuclear magnetic resonance ($^1H$ NMR)를 통해 구조확인을 하였고, X-ray Photoelectron Spectroscopy (XPS)를 통해 화학조성에 대한 정량적 분석을 하였다. 막 성능은 함수율 및 이온교환용량과 전기저항을 측정하였고. $60^{\circ}C$에서 7시간 술폰화한 SPVDF 멤브레인이 이온교환용량 0.89 meq/g, 함수율 21.5%, 전기저항 $3.70{\Omega}{\cdot}cm^2$로 가장 우수하였다. 수중 이온제거 특성을 막 축전식 탈이온 방법(MCDI)으로 전압(0.9~1.5 V), 유속(10~40 mL/min)을 변수로 SPVDF의 탈염 특성을 확인하여 MCDI 공정에 적용가능 여부를 평가하였다. MCDI 충방전 시험 결과 최대 탈염제거율은 62.5%이었다.

• 멤브레인
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• 제25권5호
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• pp.431-439
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• 2015

이 연구는 양이온 불균질막을 제조하기 위해 PVdF와 상용 양이온교환수지를 배합하여 제조하고 최적의 조건제시 및 기존 상용화막과 비교 평가하였다. 연구결과 불균질막이 기존의 상용화막보다 이온교환용량, 전기저항, 함수율 부분에서 높은 물성을 나타내기 위해서는 이온교환수지의 무게 비율을 40% 이상 첨가해야 한다는 것을 확인하였다. 인장강도가 상용화막보다 높기 위해서는 이온교환수지의 무게 비율을 50% 이하로 첨가해야 한다는 것을 확인하였다. 따라서 화학적 특성과 기계적 특성을 고려했을 때, PVdF와 이온교환분말의 최적 비율은 60 : 40이며, 이때의 전기저항 $1.82{\Omega}{\cdot}cm^{-1}$, 함수율 79%, 이온교환용량 1.60 meq/g으로 측정되었고 기계적 강도는 0.97 MPa로 측정되었다. 이때, TDS 제거율은 약 40%로 측정되었다.

• Bulletin of the Korean Chemical Society
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• 제34권9호
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• pp.2657-2662
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• 2013

Multiwalled carbon nanotube (MWCNT)-g-poly (aniline-co-2,5-diaminobenzenesulfonic acid) (DABSA) reinforced Nafion$^{(R)}$ nanocomposite membranes were prepared and characterized for direct methanol fuel cells (DMFCs). The nanocomposite membranes with approximately $90{\mu}m$ thickness were prepared by the water assisted solution casting method. To evaluate the properties of nanocomposite membranes for DMFC applications, the nanocomposite membranes were characterized by methanol and water uptake, thermal stability, and ion exchange capacity (IEC). Furthermore, oxidative stability measurements in terms of the hydrogen peroxide decomposition rate that represent the oxidative stability of the membranes were examined. The methanol uptake values of the nanocomposite membranes were dramatically decreased compared to the cast Nafion$^{(R)}$ membranes. The IEC values of the nanocomposite membranes were increased about 30% compared to the cast Nafion$^{(R)}$ membrane.

• 유기물자원화
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• 제15권4호
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• pp.107-114
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• 2007

다당류의 일종인 알긴산을 이용한 중금속 제거에 관한 연구가 수행되어졌다. 알긴산은 pH 4에서 480mg/g의 납 이온을 흡착하였으며 이것은 다른 생물흡착제에 비해서 약 2배 정도의 높은 흡착능이다. 납 이온에 대한 등온흡착선을 묘사하기 위하여 Langmuir model 식을 이용하였으며 실험결괴는 모델식에서 얻어진 결과와 잘 부합되었다. 온도가 증가함에 따라서 흡착능은 증가하였으며 이는 알긴산과 납 이온의 흡착은 흡열반응임을 보여준다. 납 이온의 흡착에 대한 알칼리 금속(칼슘, 마그네슘 이온)의 영향은 거의 없었으며 대부분의 흡착은 30분 내에 이루어졌다. 구리, 수은, 스트론튬, 세슘 과 같은 다른 금속 이온에 대한 흡착능도 조사되었다.

• Carbon letters
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• 제9권1호
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• pp.8-16
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• 2008

Oxidized activated carbons were prepared by reacting steam-activated carbon developed from pecan shells with nitric acid of varying strength (15, 30, 45 and 60%). The textural properties and the chemistry of the surface of the non-oxidized and of the oxidized carbons were determined from nitrogen adsorption and base neutralization capacities. The uptake of Pb(II) and Cd(II) from aqueous solution by these carbons was determined by kinetic and equilibrium experiments as well as by the column method. Treatment with nitric acid brought about drastic decrease in surface area and remarkable increase in the pore size of the carbon with these changes depending on the strength of nitric acid. Nitric acid increased the surface acidity by developing new surface oxygen functional groups of acidic nature. $HNO_3$-oxidized carbons exhibited high adsorption capacities for Pb(II) and Cd(II). The adsorption of these ions increased with the decrease of the surface pH of the carbon and with the increase of the solution pH from 2.5 to 6 and 7. The amount adsorbed from lead and cadmium was also related to the amount of surface acidity, the pH of the point of zero charge and on some metal ion parameters. Cadmium and lead uptake by the investigated carbons followed pseudo-second order model and the equilibrium sorption data fitted Langmuir adsorption model.