• 환경위생공학
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• 제15권1호
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• pp.95-101
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• 2000

This study was investigated to the reaction of alumina sintering with alkaline. The soluble $NaAlO_2$ was made after the commercial ${\alpha}-Al_2O_3$ was calcinated with NaOH. The reaction of alumina was carried out to be based on the effects of calcination temperature, time, and the mixing ratio of ${\alpha}-Al_2O_3/NaOH$. The alumina was calcined over $500^{\circ}C$ with NaOH powder after it was sieved with 170/270 mesh. The calcined alumina with NaOH powder was dissolved into $25^{\circ}C$ distilled water and filtrated, and HCI was added to adapt pH 6.5~7.5. The residue was separated with vacuum pump for filtration after it was adapted to proper pH, and aluminum compound was precipitated with $Al(OH)_3$. The investigation was carried out with the variables; the calcination temperature($500-900^{\circ}C$), the calcination time (30~90 min), and the concentration of HCI when leaching(0.5~3.0N) respectively. In this investigation, the main product of ${\alpha}-Al_2O_3$ and NaOH was $NaAlO_2$ and the maximum conversion ratio was 91.4% under the optimum conditions as followed ; the ratio of NaOH/${\alpha}-Al_2O_3$ was 1.5 and the calcination conditions were $800^{\circ}C$ and 90 min.

• 한국환경과학회지
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• 제23권5호
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• pp.887-893
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• 2014

In order to remove fluoride ions from aqueous solution, PVC-$Al(OH)_3$ beads were prepared by immobilizing $Al(OH)_3$ with polyvinyl chloride (PVC). The prepared PVC-$Al(OH)_3$ bead was characterized by using SEM, EDS and Zeta potential. Dependences of pH, contact time and initial fluoride concentration on the adsorption of fluoride ions were studied. The optimal pH was in the range of 4~10. The adsorption was rapid during the initial 12 hr, and equilibrium was attained within 72 hr. The adsorption rate of fluoride ions by PVC-$Al(OH)_3$ beads obeyed the pseudo-second-order kinetic model. The maximum adsorption capacity obtained from Langmuir isotherm model was found to be 62.68 mg/g.

• Korean Chemical Engineering Research
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• 제48권2호
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• pp.205-211
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• 2010

상 하수 응집제인 폴리염화알루미늄(polyaluminumchloride, PAC)과 가성소다(NaOH)를 이용하여 수산화알루미늄을 합성하고, 가성소다(NaOH) 첨가량 변화에 따른 합성물 특징을 고찰하였다. 이 때 합성된 수산화알루미늄의 특징을 XRD, SEM, PSA로 분석하였다. XRD 분석 결과, NaOH 15g에서는 비정질 수산화알루미늄로, NaOH 20g에서는 깁사이트(gibbsite)(37%), 바이어라이트(bayerite)(35%), 보헤마이트(boehmite)(28%)의 혼합상(mixed phase)으로 나타났으며, NaOH 25g에서는 깁사이트(gibbsite)(67%), 바이어라이트(bayerite)(33%)로, NaOH 30g에서는 깁사이트(gibbsite) (83%), 바이어라이트(bayerite)(17%)로 나타났다. SEM 분석 결과, NaOH 25, 30g에서 판형 형태로 분석되었다. PSA 분석 결과, 수산화알루미늄의 입자 크기는 NaOH 첨가량이 증가할수록 감소하였다.

• 생명과학회지
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• 제24권1호
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• pp.74-80
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• 2014

본 연구에서는 다양한 약효가 있다고 알려진 애기땅빈대(Euphorbia supina)의 추출물 및 분획물의 지방산 조성을 분석하고 인체 암세포 증식 억제효과에 대하여 살펴보았다. A+M과 MeOH 추출물의 지방산 조성 패턴은 유사했고 A+M과 MeOH 추출물은 각각 53.4% 및 42.1%의 18:3n-3를 함유하였다. 분획물들 중 85% aq. MeOH는 가장 높은 함량의 18:3n-3를 나타내었다. 애기땅빈대에 의한 암세포 증식 억제효과는 MeOH 추출물과 비교했을 때 A+M 추출물에 의한 억제효과가 높았으며 AGS 인체 위암세포에 대한 억제효과가 높았다. 분획물들 중에서는 n-Hexane과 85% aq. MeOH 분획물들에 의한 증식 억제효과가 높았다. 따라서 애기땅빈대의 항암 활성 성분은 n-Hexane과 85% aq. MeOH 분획물들에 함유되어 있는 것으로 여겨지며 향후 정제하여 규명할 필요가 있다고 사료된다.

• 자연과학논문집
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• 제9권1호
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• pp.95-104
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• 1997

본 연구에서는 thymidine으로부터 시작하여 3'-OH과 5'-OH의 각각의 변형, 동시의 변형을 통해 크게 5종의 amino thymidine 골격의 촉매를 합성하였다. 다양한 thymidine 화합물들이 새로운 키랄 보조체로서의 촉매효과를 위해 우선 3'-OH 자리에 mono-methylamino thymidine과 dimethylamino thymidine을 합성하고, 이들의 합성과정을 응용하여 5'-OH을 Ac-O로 변환한 5'-acetyl-3'-dimethylamino thymidine과 5'-OH를 TBS로 변환하고 up위치의 azido화합물인 5'-TBS-3'-Up-tBOC methylamino thymidine을 합성하였다. 그리고, 5'-OH를 amino group으로 변환하고 3'-OH를 -Me로 변환한 화합물 3'-acetyl-5'-tBOC-amino thymidine을 합성하였다.

• Bulletin of the Korean Chemical Society
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• 제23권6호
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• pp.811-817
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• 2002

Gibbs ensemble Monte Carlo simulations were performed to calculate the vapor-liquid coexistence properties for the binary mixtures $CO_2/CH_3OH$, $CO_2/C_2H_5OH$, and $CO_2/CH_3CH_2CH_2OH.$ The configurational bias Monte Carlo method was used in the simulation of alcohol. Density of the mixture, composition of the mixture, the pressure-composition diagram, and the radial distribution function were calculated at vapor-liquid equilibrium. The composition and the density of both vapor and liquid from simulation agree considerably well with the experimental values over a wide range of pressures. The radial distribution functions in the liquid mixtures show that $CO_2$ molecules interact more stogly with methyl group than methylene group of $C_2H_5OH$ and $CH_3CH_2CH_2OH$ due to the steric effects of the alcohol molecules.

• 한국결정성장학회지
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• 제9권1호
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• pp.70-73
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• 1999

$SiO_{2}/(NaOH+Na_{2}CO_{3})=2~20\;and\;H_{2}O/(NaOH+Na_{2}CO_{3})=200~250$인 몰 비 조건에서 무저어형 심리카를 $170~180^{\circ}C$, 48~120시간에 걸쳐 수열반응 시켰다. $SiO_{2}/(NaOH+Na_{2}CO_{3})=3~20$의 몰비 조건에서 Na-kenyaite 결정은 중간 생성물인 Na-magadiite 결정의 생성을 거치지 않고 무정형 실리카로부터 직접 형성되었다. $SiO_{2}/(NaOH+Na_{2}CO_{3})=3~10$ 이상의 몰 비에서는 항상 Na-kenyaite와 함께 무정형 실리카가 잔류물로 남아있었다. 전자 현미경으로 관찰한 Na-kenyaite와 함께 무정형 실리카가 잔류물로 남아있었다. 전자 현미경으로 관찰한 Na-kenyaite 결정 모양은 꽃잎 모양의 판들이 모여서 이루어진 둥근 다발과 같은 형태를 보여주었으며, 반응시간이 경과하면 결정 다발은 개개의 판들로 나누어진 보다 작은 조각들로 분리된 모양을 보여주었다.

• Nuclear Engineering and Technology
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• 제34권5호
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• pp.517-531
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• 2002

The speciation and solubility of Am, Np, Pu and U have been analyzed by means of the geochemical code MUGREM, under the chemical conditions of domestic deep groundwater, in order to support the preliminary safety assessment for a Korean HLW disposal concept. Under the conditions of groundwaters studied, the stable solid phase is AmOHC $O_3$(s) or Am(OH)$_3$(s), soddyite((U $O_2$)$_2$ $SiO_2$.2$H_2O$) or N $a_2$ $U_2$ $O_{7}$ (c), Np(OH)$_4$(am), and Pu(OH)$_4$(am) for Am, U, Np, and Pu, respectively. The dominating aqueous species are as follows: the complexes of Am(III), Am(OH)$_2$$^{+}$ and Am(C $O_3$)$_2$$^{[-10]}$ , the complexes of U(VI), U $O_2$(OH)$_3$$^{[-10]}$ and U $O_2$(C $O_3$)$_3$$^{4-}$, the complexes of Np(IV), Np(OH)$_4$(aq) and Np(OH)$_3$C $O_3$, and the complexes of Pu(IV), Pu(OH)$_4$(aq) and Pu(OH)$_3$C $O_3$$^{[-10]}$ . The calculated solubilities exist between 1.9E-10 and 1.3E-9 mol/L for Am, between 5.6E-6 and 1.2E-4 mol/L for U, between 3.1E-9 and 1.3E-8 mol/L for Np, and between 6.6E-10 and 2.4E-10 mol/L for Pu, depending on groundwater conditions. The present solubilities of each actinide agree well with the results of other studies obtained under similar conditions.s.

• 대한화학회지
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• 제13권2호
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• pp.157-164
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• 1969

Aoolphane was treated with 30% Hydrochloric acid at $18^{\circ}C$ for two hows with stirring in order to obtain the insoluble form of SiO2 gel and to extract quantitatively both $Al_2O_3$as and $Fe_2O_3AlCl_3{\cdot}6H_2O Fe$ and $Cl_3{\cdot}6H_2O$ forms, respectively, at the same time. $SiO_2$ gel was filtered and to the filterate Ammonia was added to precipitate $Al(OH)_3[Fe(OH)_3 Contaminated ]$ The precipitate was separated by filteration and the filterate was recovered as the form of $NH_4Cl$. The precipitate was treated with 200g (NaOH)/l Concentration of NaOH a little excessively to the equivalent at $65~70^{\circ}C$ as $Fe(OH)_3$ formed was insoluble, it was filtered of and to the filterate containing $NaAl(OH)_4(OH_2)_2$Carbon dioxide gas was bubbled at $50^{\circ}C~90^{\circ}C$ to obtain the precipitate with excellent filterability and crystallinity. The product was certified to be Dawsonite $(NaAl(OH)_2CO_3)$ by X-Ray diffraction analysis at below $40^{\circ}C$, when $CO_2$ gas was bubbled into the relatively lower concentration of $NaAl(OH)_4(OH_2)_2$ solution, the precipitate of very fine particles was formed, which was hard to filter and with the Composition of $\alpha-Al_2O_3-H_2O$ (Boehmite).

• 대한화학회지
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• 제39권7호
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• pp.578-584
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• 1995

$Sr(OH)_2$가 소량 첨가된 수산화칼슘 수용액에 $CO_2$ 가스를 흡수시켜 탄산화 반응을 행하였으며, 이 반응에서 반응온도와 $Sr(OH)_2$가 탄산화반응에 미치는 영향을 조사하였다. 주상형의 aragonite는 반응온도가 높을수록, $Sr(OH)_2(aq)/Ca(OH)_2(aq)$의 비가 클수록, 즉 $OH^-/CO_2(aq)$의 비가 클수록, 잘 생성되었다. $Sr(OH)_2$는 탄산화반응 초기에 aragonite와 유사한 사방정형의 $SrCO_3$를 쉽게 형성하고, 물에 대한 용해도가 높기때문에 $OH^-$ 이온을 증가시켜 용액내에 결정성장에 유리한 $CO_3^{2-}$ 이온을 보다 쉽게 형성시키므로 주상형 aragonite 생성에 유리한 역할을 하였다.