• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.2
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• pp.81-88
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• 2007

A study on the removal of heavy metals using sawdust was performed. Among heavy metals such as lead, copper and cadmium ions, uptake capacity of lead ions was the highest as about 0.22 mmol/g-dry mass at pH 4. The surface condition and existence of lead ions onto the sawdust was confirmed by the FT-IR, SEM (Scanning Electron Microscopy), and EDX (Energy Dispersive X-ray) instrumental analyses. When 0.5g of sawdust was added to initial lead solution (100ppm) removal efficiency was approximately 90%. Isothermal adsorption curve for lead ions was described by the Langmuir model equation and experimental data well fitted to model equation. Most adsorption for lead ions was also completed within 60min and pH of lead solution from 5.8 to 4.5 decreased with time.

• Membrane Journal
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• v.29 no.6
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• pp.308-313
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• 2019

In this study, the Fe₃O₄/porous carbon composite was synthesized by hydrothermal method for removal of Cu²⁺ ions and the characteristic of Cu²⁺ ions removal was performed. The Fe₃O₄/porous carbon composite was investigated via using SEM, XRD for its morphology and structure. BET analysis was conducted to conform a specific area and pore size distribution of the composite. For the investigation of the performance for removal of Cu²⁺ ions in the solution, UV-vis spectrometer was used. It suggests that a synergetic effect between magnetic Fe₃O₄ and porous carbon shows an improvement for removal of Cu²⁺ ions.

• Bulletin of the Korean Chemical Society
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• v.25 no.6
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• pp.809-812
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• 2004

Complexation reactions of nitrilotriacetate (NTA) and penicillamine with $Cu^{2+}$ and $Co^{2+}$ have been studied in solution phase using paper electrophoresis technique. The stability constants of the complexes Cu(II)-nitrilotriacetate-penicillamine and Co(II)-nitrilotriacetate-penicillamine have been found to be $6.64{\pm}0.03\;and\;5.86{\pm}0.05$ (logarithm stability constant values), respectively at 35$^{\circ}C$ and ionic strength 0.1 M.

• Korean Journal of Poultry Science
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• v.16 no.1
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• pp.17-22
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• 1989

In order to dull heat sensitivity of egg albumen, metal ions (aluminium, ferric, ferrous, copper) were added and functional properties or egg albumen were determined before and after heat treatment at $60^{\circ}C$ for 5 minutes. Effect of pH on heat sensitivity of aluminium salt added egg albumen was also determined. Addition of metal ions increased turbidity of egg albumen before and after the heat treatment. Changes of the turbidity were minimized by addition of aluminium salt. The foaming power was markedly increased by addition of ferric salt before the heat treatment and increased by addition of aluminium, ferric and copper salt after the heat treatment. Before the heat treatment the foam was stable by addition of ferric and ferrous salt but after the heat treatment it was stable by addition of aluminium and ferric salt. The turbidity and foaming property of the egg albumen with aluminium salt were not largely changed after the heat treatment at pH range 7 to 8.5. Over pH 9 the turbidity and foaming power were not decreased, but the foam stability was increased before and after the heat treatment. Salmonella typhimurium ATCC 14028 (10$^{6}$ cells/$m\ell$) inoculated in egg albumen at pH range 7 to 8.5 was destructed by the heat treatment.

• Resources Recycling
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• v.22 no.5
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• pp.13-19
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• 2013

The effect of pH on the citrate leaching behavior of heavy metal ion was investigated to develop an eco-friendly process for removing heavy metals from soil contaminated with copper, zinc, and lead. The leaching tests were performed using citrate solution with pH adjusted by mixing citric acid and sodium citrate under the following leaching conditions: particle size, under $75{\mu}m$; temperature, $50^{\circ}C$; citrate concentration, $1kmol/m^3$; pulp density, 5%; shaking speed, 100 rpm; leaching time, 1 hour. The difference of pH before and after the leaching test was not observed, and this result indicates the direct effect of hydrogen ion concentration on the leaching of metals was insignificant. The removal ratios of copper, zinc, and lead from the contaminated soil decreased with increasing pH. The thermodynamic calculation suggests that the leaching behaviors of metal ions were determined by two reactions; one is the reaction to form complex ions between heavy metal ions and citrate ion species, and the other is the reaction to form metal hydroxide between heavy metal ions and hydroxide ion.

• Journal of the Korean Chemical Society
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• v.30 no.5
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• pp.456-464
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• 1986

The complex formation of branched poly(ethylene imine) (BPEI) with bivalent transition metal ions, such as Fe(II), Co(II), Ni(II) and Cu(II), have been investigated in terms of visible absorption and pH titration methods in an aqueous solution in 0.1M KCl at 30${\circ}$. The stability constants for M(II)-BPEI complexes was calculated with the modified Bjerrum method. The formation curves of M(II)-BPEI complexes showed that Fe(II), Co(II), Ni(II) and Cu(II) ions formed coordination compounds with four, two, two, and two ethylene imine group, respectively. In the case of Cu(II)-BPEI complex at pH 3.4 ∼ 3.8, ${\lambda}_{max}$ was shifted to the red region with a decrease in the acidity. The overall stability constants (log $K_2$) increased as the following order, Co(II) < Cu(II) < Ni(II) < Fe(II).

• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.181-188
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• 2013

The effect of transition metal ion exchange into UZM-9 zeolite with LTA framework on its deactivation in methanol-to-olefin (MTO) conversion was discussed. The ion exchange of copper, cobalt, nickel, and iron did not induce any notable change in the crystallinity, crystal morphology, and acidity of UZM-9. The small cage entrance of UZM-9 caused the high selectivity to lower olefins in the MTO conversion, while its large cages allowed the rapid further cyclecondensation of active intermediates, polymethylbenzenes including hexamethylbenzene, resulting in a rapid deactivation. The UZM-9 containing copper and cobalt ions showed considerably slow deactivations. The interaction between transition metal ions and polymethylbenzene cation radicals, the active intermediates, generated in the MTO conversion stabilized the radicals and slowed down the deactivation of UZM-9.

• Journal of Energy Engineering
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• v.6 no.1
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• pp.26-33
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• 1997

Highly crystalline Cu-ZSM5 was prepared without using organic templates. Several ion exchange treatments between Na$\^$＋/ and Cu$\^$2＋/ brought about excess loading of copper ions on the ZSM5 zeolite and the resultant zeolite was active for the decomposition of NO. This indicates that the copper ions excessively loaded on the ZSM5 zeolite are effective for the NO decomposition. When oxygen was added to a reactants, the conversion of NO decreased. NO, O$_2$TPD experiments explained that the active sites for NO decomposition and the adsorption sites of O$_2$, were the same. O$_2$, at the surface of ZSM5 zeolite was desorbed incompletely after pretreatment at 500$^{\circ}C$, and CU-ZSM5 pretreated with H$_2$at 500$^{\circ}C$ showed promoted activity at the start of reaction. Thus, it seems clear that O$_2$, adsorbed ai the surface of catalyst inhibits the catalytic activity.

• Bulletin of the Korean Chemical Society
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• v.28 no.8
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• pp.1375-1382
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• 2007

A column preconcentration method with pulverized Amberlite XAD-4 loaded with bismuthiol I (BI) has been developed for the determination of trace Cd(II) and Cu(II) in various real samples by flame atomic absorption spectrophotometry. Various experimental conditions, such as the size of XAD-4, adsorption flow rate, amount of bismuthiol I, stirring time for adsorbing bismuthiol I on XAD-4, pH of sample solution, amount of XAD-4- BI, desorption solvent, and desorption flow rate, were optimized. Also, the adsorption capacity and the adsorption rate of Cd(II) and Cu(II) on XAD-4-BI were investigated. The interfering effects of various concomitant ions were investigated, Bi(III), Sn(II) and Fe(III) were found to affect the determination. But the interference by these ions was completely eliminated by adjusting the amount of XAD-4-BI resin to 0.70 g, although the adsorption flow rate was slower. For Cd(II) our proposed technique obtained a dynamic range of 0.5-40 ng mL-1, a correlation coefficient (R2) of 0.9913, and a detection limit of 0.3 ng mL-1. For Cu(II), the corresponding values were 2.0-120 ng mL-1, 0.9921 and 1.02 ng mL-1. To validate this proposed technique, the aqueous samples (stream water, reservoir water, tap water and wastewater), the diluted brass sample and the plastic sample, as real samples, were used. Recovery yields of 91-103% were obtained. These measured data were not different from ICP-MS data at 95% confidence level. Our proposed method was also validated using rice flour CRM (normal, fortified) samples. From the results of our experiment, we found that the technique we present here can be applied to the determination of Cd(II) and Cu(II) in various real samples.

• Journal of the Korean Electrochemical Society
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• v.7 no.1
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• pp.26-31
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• 2004

The direct electrochemical studies of four laccases (plant and fungal laccases) have been investigated on a gold electrode functionalized with a new tether of 2.2'-dithiosalicylic aldehyde. Results from these studies indicate that the redox potential of the active site of plant laccase from Rhus vernificera is shifted to a more negative value(255 mV versus SCE) than that of fungal laccase from Pyricularia oryzae (480 mV versus SCE). Mechanistic studies indicate that the reduction of type-1 Cu precedes the reduction of type-2 and type-3 Cu ions when the electrode is poised initially at different potentials. Also a new tether, 2.2'-dithiosalicylic aldehyde, has been used to study the redox properties of two laccases (LCCI and Lccla) covalently attached to a gold electrode. An irreversible peak at 0.47V vs. SCE is observed in the cyclic voltammorams of LCCI. In contrast, the cyclic voltammograms of LCCIa contain a quasi-reversible peak at 0.18V vs. SCE and an irreversible peak at 0.50V vs. SCE. We find that the replacement of the eleven amino acids a the C-terminus with a single cysteine residue $(i.e., \;LCCI{\rightarrow}LCCIa)$ influences the rate of heterogeneous electron transfer between an electrode and the copper containing active sites $(K_{het}\;for\;LCCI=1.0\times10^{-2}\;s^{-1}\;and\;K_{het}\;for\;LCCI_a= 1.0\;times10^{-1}\;s^{-1}\'at\;0.18V\;versus\;SCE\;and\;4.0\times10^{-2}\;s^{-1}\;at\;0.50V\; versus\;SCE)$. These results show for the first time that the change of the primary structure of a protein via site-directed mutagenesis influences both the redox potentials of the copper ions in the active site and the rate of heterogeneous electron transfer.