• 대한화학회지
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• 제67권4호
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• pp.222-225
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• 2023

Metallic salts of C10-18 aliphatic carboxylic acids were prepared and their scanning electron microscopic images were analyzed for the morphology dependency with the metal and the carboxylic acid. Regardless of metal ion, metal salts of dicarboxylic acids showed a high crystallinity with a fiber image (SuA-Na). The aromatic dicarboxylates also represented a morphology of a rectangular-rod or board shapes (IA-Li, IA-Ba). With Na ion, most aliphatic carboxylate (MA, PA, SA) showed a fiber-like crystallinity. However, other monovalent Li, K and multivalent Mg, especially Al ion resulted a glassy-amorphous in the metallic salts of acids (MA, PA, SA). With divalent Ba and Ca ions, the metal salt of aliphatic acids expressed a branched round cluster shape as in SA-Ca, SA-Ba. Both Li and Mg ions with a similar size showed a strong morphological similarity in the metallic salts of aliphatic acids MA, PA, SA. In the case of Na and Ca ions with a similar size (98, 106 pm), both ionic salts of stearic acid gave a branching effect for a fiber or round granular image. In the case of hydroxyl-aliphatic acids (HLA, HPA, HSA), the fiber images in HLA-Na and HSA-Na was appeared about 100 nm thicker than those of nonhydroxycarboxylates (LA-Na, SA-Na). The metallic salts of unsaturated C-18 carboxylic acids (OlA, LeA and LnA) showed an amorphous glassy image due to a kinked carbon chain.

• 한국환경과학회지
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• 제20권10호
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• pp.1337-1345
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• 2011

The removal performances of divalent heavy metal ions ($Pb^{2+}$, $Cu^{2+}$, $Cd^{2+}$, $Sr^{2+}$ and $Mn^{2+}$) were studied using the Na-P1 zeolite synthesized from Jeju scoria in the batch and continuous fixed column reactor. The uptakes of heavy metal ions by synthetic Na-P1 zeolite decreased in the order of $Pb^{2+}$ > $Cu2^{2+}$ > $Cd^{2+}$ > $Sr^{2+}$ > $Mn^{2+}$ based on the selectivity of each ion to ionic exchange site of Na-P1 zeolite for single and mixed solutions in batch or continuous fixed column reactor. For mixed solution, each heavy metal ion uptake was lower than that in single solution, and especially the uptake for $Mn^{2+}$ decreased greatly. In batch reactor, the uptakes of heavy metal ions by synthetic Na-P1 zeolite were described by Freundlich or Langmuir equation, but they followed the former better than the latter. In continuous fixed column reactor, the maximum ion exchange capacity obtained for each of heavy metal ions, was about 90----- of that in batch reactor. The uptakes of heavy metal ions by synthetic Na-P1 zeolite increased with the increase of initial heavy metal concentration and solution pH, and the decrease of the amount and particle size of synthetic zeolite.

• 한국해양공학회지
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• 제1권1호
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• pp.111-119
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• 1987

The corrosion fatigue crack propagation characteristics of SS41 steel in 3.5% NaCl solution have been evaluated for loading frequencies of 1Hz and 0.2Hz. A sine wave loading profile was used for fatigue testing. Each test was carried out at a constant stress ratio, R(0.1). The main results are summarized as follows; 1. Fatigue crack propagation rate was higher in 3.5% NaCl solution than in air, higher in the base metal than in the weld metal, and higher at f =0.2Hz than at f =1Hz. 2. The crack closure level of the base metal was not influenced by cyclic frequencies, but that of the weld metal was much influenced. 3. When the crack closure effect was eliminated in the evaluation of crack propagation characteristics by using $\Delta K_{eff}$, the envirommental influence was distinctly observed. At the base metal, crack propagation rate was enhanced by the hydrogen embrittlement, and the weld metal was reduced by the crac closure. 4. There was clearly observed hydrogen embrittlement and severely corroded aspect at fracture surface of lower frequency than that of higher frequency, and at that of base metal than that of the weld metal.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권7호
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• pp.103-111
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• 2015

Soil washing with ethylenediaminetetraacetic acid (EDTA) is highly effective in the remediation of soils contaminated with heavy metals. The EDTA recycling process is a requisite for reducing the operating cost. The applicability of Na₂S addition on the precipitation of heavy metals from the spent soil washing solution and thereby recycling of EDTA was investigated. Addition of Na₂S into the single metal-EDTA and the mixed metal-EDTA solutions ([Na₂S]/[metal-EDTA] ratio = 30, reaction time = 30 min and pH = 7~9) was highly effective in the separation of Cu and Pb from metal-EDTA complexes, but not for Ni. The Zn removal efficiency varied with pH and slightly increased upto 40% as the reaction time increased from 0 to 240 min which was longer than those for Cu and Pb. Ca(OH)₂ was subsequently added to induce further precipitation of Zn and Ni and to reduce the Na₂S dose. At the [Na₂S]/[metal-EDTA] ratio of 10, the removal efficiencies of all heavy metals excluding Ni were above 98% with the dose of Ca(OH)₂ at 0.002, 0.006 and 0.008 g into 100 mL of Cu-, Pb- and Zn-EDTA solutions, respectively. However, Ca(OH)₂ addition was not effective for Ni-EDTA solution. A further research is needed to improve metal removal efficiency and subsequent EDTA recycling for the real application in field-contaminated soils.

• 분석과학
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• 제7권3호
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• pp.271-276
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• 1994

셀룰로스에 대한 +2와 +3가 금속이온들의 흡착성을 최적 조건에서 실험하였는데, +2가 금속이온으로 Cu(II), Zn(II), Pb(II) 및 Cd(II) 이온을 선택하였으며, +3가 금속이온으로 Cr(III)와 Fe(III) 이온을 선택하여 실험하였다. 셀룰로스에 대한 흡착능을 증대시키기 위하여 셀룰로스를 2M NaOH로 처리하여 Na-셀룰로스를 제소하였다. 셀룰로스에 대한 금속이온 흡착능은 매우 작아서 고분자 흡착제로서의 효과가 없었으나 Na-셀룰로스는 고분자 흡착제로서 매우 효과적이었다. Na-셀룰로스에 대한 금속이온들의 흡착은 뱃치법으로 실험하였다. 최적 조건에서 Na-셀룰로스에 대한 금속이온들의 흡착은 +2가 금속이온들은 1:2, +3가 금속이온들은 1:3의 흡착비로 흡착하는 이온교환 흡착이었다. Na-셀룰로스에 대한 금속이온들의 흡착엔탈피는 -18kcal/mol 정도였으며, carboxymethylcellulose(CMC)와 Dowex 50W-X8 수지와 비교 실험한 결과, Na-셀룰로스에 대한 금속이온들은 흡착은 이온교환흡착으로, 비슷한 작용기를 가지고 있는 CMC와 비슷한 흡착엔탈피를 보였다.

• Bulletin of the Korean Chemical Society
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• 제32권5호
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• pp.1685-1691
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• 2011

The molecular structures of thiacalix[4]biscrown-5 (1) and p-tert-butylthiacalix[4]biscrown-5 (2) and their alkali-metal-ion complexes were optimized using the DFT BLYP/6-31G(d) and mPW1PW91/6-31G(d,p) (hybrid HF-DF) calculations. The total electronic energies, the normal vibrational modes, and the Gibbs free energies of the mono- and di-topic complexes of each host with the sodium and potassium ions were analyzed. The $K^+$-complexes exhibited relatively stronger binding efficiencies than $Na^+$-complexes for both the monoand di-topic complexes of 1 and 2 comparing the efficiencies of the sodium and potassium complexes with an anisole and phenol. The mPW1PW91/6-31G(d,p) calculated distances between the oxygen atoms and the alkali metal ions were reported in the alkali-metal-ion complexes ($1{\cdot}Na^+$, $1{\cdot}2Na^+$, $1{\cdot}K^+$, $1{\cdot}2K^+$, $2{\cdot}Na^+$, $2{\cdot}Na^+$, $2{\cdot}K^+$, $2{\cdot}2K^+$). The BLYP/6-31G(d) calculated IR spectra of the host 1 and its mono-topic alkali-metal-ion complexes are compared.

• Korean Chemical Engineering Research
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• 제40권6호
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• pp.669-675
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• 2002

액상 NaK alloy, Na metal 그리고 지지체에 담지된 Na metal을 촉매로 이용하여 o-xylene과 1,3-butadiene의 alkenylation을 통한 OTP(ortho-tolyl pentene)의 합성 반응을 연구하였다. 액상의 NaK alloy 촉매인 경우 metal의 분산도를 증가시키기 위해서 ultrasound로 처리하였고 촉매상은 매우 작은 입자로 쪼개져 emulsion을 형성하면서 분산도를 증가시킬수록 전화율과 선택도를 향상시킬 수 있었다. Na metal의 경우 분산도를 증가시키기 위해 전처리가 필요하였으며 미립자로 분산이 진행되는 동안 지체(induction) 시간이 필요하였다. 지지체에 담지된 Na metal의 경우 지지체에 관계없이 80 % 이상의 전화율을 지체 시간 없이 얻을 수 있었다. 하지만 slurry 액상 반응계에서는 담지된 금속의 85 % 이상이 촉매에서 떨어져 나와 반응에 참여하는 것으로 보인다. 반응물인 1,3-butadiene과 생성물인 OTP간의 반응에 의한 부반응이 진행되어 1,3-butadiene의 양이 증가하면 부반응으로 생성된 oligomer 양이 증가하였으며 전화율이 증가하면 선택도가 반비례 관계로 감소하였다.

• 한국환경과학회지
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• 제1권2호
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• pp.167-175
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• 1992

This study was conducted for an efficient utilization of waste fly ash obtained from the power plant. Fly ash was used for synthesizing zeolite. Na-Pl zeolite could be easily synthesized from waste fly ash and showed the potential to remove heavy metal ions. The synthetic zeolite showed good adsorption property for heavy metal much better than raw fly ash and natural zeolites. Na-Pl exhibited the high adsorption efficiency with a maximum value of 260 Pb mg/g and strong affinity for Pb2+ ion. The metal ion selectivity of Na-Pl was determined in a decreasing order : $Pb^{2+}$>$Cd^{2+}$>$Cu^{2+}$+>$Zn^{2+}$>$Fe^{3+}$

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제1권2호
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• pp.167-175
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• 1997

This study was conducted for an efficient utilization of waste fly ash obtained from the power plant. Fly ash was used for synthesizing zeolite. Na-P1 zeolite could be easily synthesized from waste fly ash and showed the potential to remove heavy metal ions. The synthetic zeolite showed good adsorption property for heavy metal much better than raw fly ash and natural zeolites. Na-P1 exhibited the high adsorption efficiency with a maximum value of 260 Pb mg/g and strong affinity for $Pb^{2+}$ ion. The metal ion selectivity of Na-P1 was determined in a decreasing order : $Pb^{2+}>Cd^{2+}>Cu^{2+}>Zn^{2+}>Fe^{3+}$.

• 한국환경과학회지
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• 제8권3호
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• pp.399-409
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• 1999

The three domestic natural zeolites(Yong dong-ri (Y), Daesin-ri (D), Seogdong-ri (S)) harvested in Kyeongju-shi and Pohang-shi, Kyungsangbug-Do, were pretreatd with each of the NaOH, $Ca(OH)_2$ and NaOH following HCl solutions, and the removal performances of divalent haevy metals(Cu, Mn, Pb, and Sr) for natural and pretreated zeolites were investigated and compared in the single and mixed solutions. The natural zeolite-heavy metal system attained the final equilibrium plateau within 20 min, irrespective of initial heavy metal concentration. The heavy metal uptakes increased with increasing initial heavy metal concentration and pH. The heavy metal uptakes for natural zeolites decreased in the following sequences : D>Y>S among the natural zeolites; Pb>Cu>Sr>Mn among the heavy metals. The pretreated zeolites showed higher heavy metal removal performances than natural zeolites and decreased in the order of NaOH, NaOH following HCl, $Ca(OH)_2$ treatment among the pretreatment methods. The heavy metal ion exchange capacity by natural and pretreated zeolites was described either by Freundlich equation or Langmuir equation, but it followed the former better than the latter. The heavy metal uptakes for natural zeolites decreased in the mixed solution, in comparing with those in the single solution and especially, the manganese uptake decreased greatly in the mixed solution. The pretreated zeolites showed the improved removal performances of heavy metals in the mixed solution than in the single solution and the heavy metal uptakes by those in the mixed solution showed the same trends in the single solution among the chemical treatment methods and heavy metals.