• Bulletin of the Korean Chemical Society
• /
• 제35권10호
• /
• pp.3063-3070
• /
• 2014

In this study, poly(N-methylol methacrylamide) (NMMAAm) and poly(N-methylol methacrylamide/vinyl sulphonic acid) (NMMAAm-VSA) hydrogels were synthesized by $^{60}Co-{\gamma}$ ray irradiation at an ambient temperature. The graphs belonging to the gelation percent- percent-dose and swelling curves were drawn by using data which were obtained from water and different pH solutions. Characterization of hydrogels was performed by FTIR and DSC-TGA analysis. Heavy metal ion ($Ni^{2+}$, $Co^{2+}$) removal capacities of hydrogels were investigated in aqueous solutions, which had different concentrations (100-1500 mg/L). In metal ion removal studies, pH value of aqueous medium was kept constant at 5.0. Maximum metal ion removal values were obtained for NMMAAm-VSA (1:3 mole ratio) hydrogels. Metal ion removal capacities of NMMAAm-VSA (1:3 mole ratio) hydrogels were found as 82 mg/g and 98 mg/g for $Ni^{2+}$ and $Co^{2+}$ ions, respectively.

• Bulletin of the Korean Chemical Society
• /
• 제14권6호
• /
• pp.687-691
• /
• 1993

Complexation of $Cd^{2+},\;Pb^{2+}\;and\;Hg^{2+}$ ions with four cryptands were studied by potentiometry and solution calorimetry in various weight percent methanol-aqueous solvent at 25${\circ}$C under $CO_2$free nitrogen atmosphere. The stabilities of the complexes were dependent on the cavity size of macrocycles. The $Hg^{2+}$ ion stability constants are higher than those of $Cd^{2+}\;and\;Pb^{2+}$ ion. All the cryptands formed complexes having 1 : 1 (metal to ligand) mole-ratio except for $Hg^{2+}-L_1$ (cryptand 1,2b: 3,5-benzo-9,14,17-trioxa-1,7-diazabicyclo-(8,5,5) heptadecane) and $Cd^{2+}-L_2$ (cryptand 2,2b: 3,5-benzo-10,13,18,21-tetraoxa-1,7-diazabicyclo (8,5,5) eicosane) complexes. $Hg^{2+}-L_1$ complex was a sandwitch type, and the $Cd^{2+}-L_2$ complex showed two stepwise reactions. Thermodynamic parameters of the $Cd^{2+}-L_2$ complex were $6.08(log\;K_1)$, -7.28 Kcal/mol $({\Delta}H_1)$, and $4.78\;(log\;K_2)$, -4.62 Kcal/mol $({\Delta}H_2)$, respectively, for 1 : 1 and 2: 1 mole-ratio. The sequences of the selectivity were increased in the order of $Hg^{2+}\;>Pb^{2+}\;>Cd^{2+}$ ion for $L_3\;and\;L_4$ macrocycles, and the $L_2$-macrocycle has a selectivity for $Cd^{2+}$ ion relative to $Zn^{2+},\;Ni^{2+},\;Pb^{2+}\;and\;Hg^{2+}$ ions. Thus, it is expected that the $L_2$ can be used as carrier for seperation of the post transition metals by macrocycles-mediated liquid membrane because $L_2$ is not soluble in water, and the difference of stability constants of the metal complexes with $L_2$ are large as compared with the other transition metal complexes. The $^1H\;and\;^{13}C-NMR studies indicated that the nitrogen atoms of cryptands have greater affinity to the post transition metal ions than the oxygen atoms, and that the planarities of the macrocycles were lost by complexation with the metal ions because of the perturbation of ring current of benzene molecule attached to macrocycles and counter-anions.

• 한국환경보건학회지
• /
• 제12권1호
• /
• pp.1-14
• /
• 1986

This investigation was carried out on the study of Ferrite formation by aerial oxidation of Fe $(OH)_2$ suspension of aqueous solution containing heavy metal ions. In this study the optimum reactionary condition of the Ferrite formation in Batch reactor wa studied by aerial oxidation which are subjected to various reaction time and temperature, under the different kinds of R(2NaOH/$FeSO_4$) Values, pH, Air flow rate, and $Fe^2+/M^2+$ mole ratio. The optimum condition for the Ferrite formation in Batch reactor was such that residence Time was 90 min., Temperature $65{\circ}$C, pH 11.0, Air flow rate 2.0l/min and $Fe^{2+}/M^{2+}$ mole ratio 4.0, which was observed by X-Ray diffraction analysis. The relation R-value, pH and ORP affecting the formation of Ferrite is that the jump step in pH 11.0, when a amount of NaOH is added, is steady state to the formation of Ferrite. Effect of R-value of $FeSO_4$ and $FeCl_2$ on the formation of Ferrite in different from each other the optimum condition of the in different from each other the optimum condition of the $FeCl_2$ is R-value 0.7, pH 11.0 and the $FeSO_4$ R-value 1.2, pH 11.0.

• 대한화학회지
• /
• 제5권1호
• /
• pp.1-6
• /
• 1961

It is important to study hydrazine because of the development of new uses for its derivatives. The Rasching method is the only satisfactory one for synthesizing hydrazine; it involves the oxidation of ammonia by sodium hypochlorite in the presence of some such catalyst as gelatin. Calcium hypochlorite was substituted for the sodium hypochlorite particularly in this work, applying agar-agar as catalyst. The results of the experiments are as follow: 1. The yield is proportional to the mole-ratio of ammonia to available chlorine in calcium hypochlorite and about 60% is obtained when the ratio is 20. 2. Agar-agar can be used as a catalyst and its proper concentration in the solution is 0.005%. 3. Proper concentration of available chlorine in the reaction solution is 0.23 mole/l. 4. The most effective condition for the reaction is a temperature of $60{\sim}65^{\circ}C.$ maintained for $20{\sim}25min$. 5. The reaction takes place equally well in either an open or closed container. 6. When calcium hypochlorite is applied in place of sodium hypochlorite, the yield of hydrazine is increased as much as 17%. 7. The yield of hydrazine is decreased by eliminating the suspension of $Ca(OH)_2$ which results from the use of calcium hypochlorite. 8. When $Ca(OH)_2$ is added to Rasching process, the yield of hydrazine is raised normally. 9. The fact that some metal ions, such as $Cu^{++},$ inhibit the formation of hydrazine was proved. 10. The suspension of $Ca(OH)_2$ acted as a remarkable adsorbent for $Cu^{++}$ like gelatin. The suspension of $Ca(OH)_2$ which results from the use of calcium hypochlorite acts as a catalyst, absorbing metal ions, to increase the yield of hydrazine. So I think that calcium hypochlorite is a more efficient oxidant than sodium hypochlorite in hydrazine syntheses.

• 한국표면공학회지
• /
• 제26권2호
• /
• pp.87-107
• /
• 1993

The grain size of the final products of WC-Co and WC-Ni composite powders is dependent on the size of the starting material and the conditions employed for the reduction and carburization. APT-Co and -Ni com-plex salts were prepared by the substitution reaction between ammonium ions in APT and the metal ions in Co(NO3)2 and Ni(NO3)2 solutions of different concentrations(0.1 to 0.7M) at $50^{\circ}C$ and the grain sizes of the com-plex salts was $0.54~0.76\mu\textrm{m}$. The complex which calcined the complex salts at $700^{\circ}$~80$0^{\circ}C$ for 60min. were 0.2~0.5$\mu\textrm{m}$. W-Co($5.92^{\circ}C$) and -Ni(6.95%) powders which reduced the complex oxides with H2d atmo-sphere(flow rate;600cc/min.) at $700^{\circ}$~$800^{\circ}C$ for 60min. were $0.5~0.6\mu\textrm{m}$. The mean grain sizes of WC-Co and WC-Ni composite powders which carburized both complex metals of W-Co and W-Ni at $800^{\circ}C$ for 60min. were $0.5~0.6\mu\textrm{m}$, and take place the coarsening of the grain above $800^{\circ}C$ and the optmium ratio of C3H8 and H2 was 0.2 for the control of the free carbon. The effect of Co contents on the particle sizes decreased from 0.4 to $0.25\mu\textrm{m}$ with increasing the content from 2.0 to 7.6w%. The activation energies on the reductions of oxides and the formations of carbides were as follows ; W-Co : Q = 8.7 kcal/mole, W-Ni : Q = 8.1 kcal/mole, WC-Co pow-der : Q = 17.8 kcal/mole, WC-Ni powder : Q = 16.6 kcal/mole.

• Bulletin of the Korean Chemical Society
• /
• 제6권4호
• /
• pp.225-228
• /
• 1985

The absorptions of Fe(Ⅲ), Tb(Ⅲ), Tl(Ⅰ), Ce(Ⅲ), Th(Ⅳ), and $UO_2^{2+}$ ions into the Dowex 50W-X2, 100-200 mesh resin were investigated by spectrophotometry to understand the abnormal strong absorption behavior of cations to cation exchange resins in concentrated HClO4. The distribution coefficients increase in the order : Tl(Ⅰ) < Fe(Ⅲ) < Tb(Ⅲ)∼Ce(Ⅲ) < $UO_2^{2+}$< Th(Ⅳ) and the order is interpreted in terms of the ratio of charge-to-ionic radius. The mole ratios of increment of $ClO_4^-$ ion absorption to metal ion absorption showed the same order as the distribution coefficients, which indicates that the electrostatic association between $ClO_4^-$ ion and metal ion plays a major role in the strong absorption.

• 한국자기학회지
• /
• 제19권6호
• /
• pp.209-215
• /
• 2009

M-type 바륨 페라이트(BaFe12O19)분말을 공침법을 이용하여 합성하였다. 출발물질의 조성은 $Fe^{3+}:\;Ba^{2+}$ 몰 비를 8로 고정하고 $Fe^{3+}$와 $Ba^{2+}$의 상대적인 양을 조절하였다. 열처리 방법과 pH의 차이에 의한 자기적 성질과 결정구조, 입자형상의 변화를 XRD(XRay Diffractometer), FESEM(Field Emission Scanning Electron Microscope), VSM(Vibrating Sample Magnetometer)을 이용하여 조사하였다. pH가 8이고 $Fe^{3+}:\;Ba^{2+}$의 비가 12 : 1.5 일 때 가장 큰 보자력 값을 얻었다. pH가 8일 때는 $Fe^{3+}$와 $Ba^{2+}$의 상대적인 양과 열처리 조건에 따라 보자력과 포화 자화 값의 변화가 크게 나타났다. 이것은 바륨 페라이트로 전이가 안 된 $\alpha$-$Fe_2O_3$ 상 때문이다. pH가 10일 때는 열처리 조건과 $Fe^{3+}$와 $Ba^{2+}$의 양과 상관없이 단일 상 M-type 바륨 페라이트를 얻을 수 있었으며 우수한 자화 값과 보자력을 나타내는 분말을 얻을 수 있었다. $Fe^{3+}$와 $Ba^{2+}$의 비가 13.6 : 1.7일 때 가장 큰 자화 값(55.7 emu/g)을 얻을 수 있었으며, 산소분위기에서 열처리 후 노냉한 분말이 높은 보자력과 자화 값을 나타내었다. FESEM으로 관찰된 입자의 크기는 50~200 nm이었다.

• 대한화학회지
• /
• 제29권4호
• /
• pp.397-405
• /
• 1985

금속킬레이트제로써 잘 알려진 몇가지 oxime 화합물들의 Amberlite XAD 수지들에 대한 흡착성을 분포계수값을 측정함으로써 상호 비교해 본 결과 킬레이트제로서는 분포계수값이 비교적 큰 salicylaldoxime (SAO)과 ${\alpha}$-benzoinoxime(${\alpha}$-BzO) 그리고 수지로서는 XAD-4 수지가 적합함을 알았다. SAO과 ${\alpha}$-BzO를 XAD-4 수지에 각각 침윤시킨 SAO-XAD-4 및 ${\alpha}$-BzO-XAD-4 침윤수지의 그 특성을 조사하였다. SAO와 ${\alpha}$-BzO의 XAD-4 수지에 대한 최적 흡착조건은 30% 메탄올, pH 1∼8(SAO) 및 pH 1~9 (${\alpha}$-BzO)였다. SAO 및 ${\alpha}$-BzO의 XAD-4 수지에 대한 흡착은 온도가 증가함에 따라 감소하였으며, 그 흡착메카니즘은 흡착엔탈피(-${\Delta}$H)를 구해본 결과 4.99 ~ 6.66 (Kcal/mol)인 것으로 보아 쌍극자-쌍극자 인력에 상응하는 분자 흡착임을 알 수 있었다. 한편 금속이온을 흡착시키는 매질용액과 흡착된 금속이온을 회수하는 염산수용액에서 침윤수지의 안정성을 조사한 결과, 전자는 pH 5∼10에서, 후자는 0.1~5M 염산수용액에서 비교적 큰 안정성을 보였다. 두 침윤수지에 의한 Mn(II), Co(II), Ni(II), Zn(II)등의 금속이온의 흡착몰비는 대략 1;2(금속이온:킬레이트제)이었으며 흡착된 금속이온은 3M-HCl 수용액 또는 3M-HCl/50%-MeOH 용리액으로 정량적으로 회수가 가능하였다.

• 대한화학회지
• /
• 제28권6호
• /
• pp.403-411
• /
• 1984

중금속이온의 흡착, 분리 및 회수를 위하여 8-Hydroxyquinoline의 할로겐유도체인 DXHQ (5,7-dihalo-8-hydroxyquinoline)들을 Amberlite XAD-7 및 XAD-4에 침윤시킨 DXHQ - XAD 침윤수지들을 만들고, 침윤수지들의 특성을 비교하였다. XAD-7 수지에 대한 DXHQ (X : Cl, Br, I)의 침윤량은 DCHQ < DBHQ < DIHQ의 순위로 증가하였고, XAD-4에 대한 DIHQ의 최적 흡착 pH 범위는 3.0~7.0였다. DXHQ - XAD 침윤수지들은 모두 pH3.0 ~7.0범위에서 안정하였고, 염산용액에서의 DIHQ - XAD의 안정성은 XAD-7의 경우보다 XAD-4가 컸다. 각 침윤수지에 의한 금속이온들의 최적 흡착 pH 범위, 흡착몰비 및 흡착능이 결정되었다. 침윤수지에서의 금속이온의 안정성은 M-DCHQ-XAD-7 < M-DBHQ-XAD-7 < M-DIHQ-XAD-7 순위로 증가하였으며, 흡착된 금속이온들은 0.5~3M HCl로 정량적 회수가 되었다. 침윤수지들의 반복 사용 실험은 5회 정도 가능하였으며, 이때 침윤된 DXHQ는 약 반이 남아 있음을 알았다.

• 대한화학회지
• /
• 제27권5호
• /
• pp.353-360
• /
• 1983

8-hydroxyquinoline의 Amberlite XAD-7 수지에 대한 최적 흡착조건의 매질용액은 pH 6.0~9.0의 30% MeOH 수용액이다. 이 매질 용액에서 XAD-4 및 XAD-7 수지에 대한 8HQ의 침윤량은 각각 3.81${\times}$10-2mmol 8HQ/g, XAD-4 resin와 2.60${\times}$10-2mmol 8HQ/g, XAD-7 resin이었다. 8HQ-XAD-4 및 8HQ-XAD-7 침윤수지는 pH 6.0-10.0 영역에서 안정하였으며, 특히 8HQ-XAD-4 수지의 경우에는 흡착된 금속이온의 회수에 사용되는 용리액인 HCl의 농도가 증가할 수록 안정도가 증가하였다. 8HQ-XAD 침윤수지에 대한 Cu(II), Cd(II), Ni(II), 및 Fe(III) 금속이온의 흡착은 pH 6.0~10.0 영역에서 최대 흡착을 보였으며, 금속이온의 흡착몰비(금속이온 : 8HQ)는 Cu(II), Cd(II), Ni(II)의 경우에는 1:2이었으며, Fe(III)의 경우는 1:3으로 나타났다. 8HQ-XAD 침윤수지에 흡착된 금속이온은 5M HCl로 용리하였을 때 정량적으로 회수되었으며, 8HQ-XAD-4 침윤수지는 5M HCl을 용리액을 사용하였을 때 침윤양의 감소없이 5회 이상 재사용이 가능하였다.