• Clean Technology
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• v.20 no.4
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• pp.367-374
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• 2014

Several experiments have been done to investigate the removal of hydrogen sulfide ($H_2S$) synthetic gas from biogas streams by means of chemical absorption and chemical reaction with 0.1-1 M Fe/EDTA solution. The roles of Fe/EDTA were studied to enhance the removal efficiency of hydrogen sulfide because of oxidizing by chelate. The motivation of this investigation is first to explore the feasibility of enhancing the toxic gas treatment in the biogas facility. The biogas purification strategy affords many advantages. For instance, the process can be performed under mild environmental conditions and at low temperature, and it removes hydrogen sulfide selectively. The end product of separation is elemental sulfur, which is a stable material that can be easily disposed with minor potential for further pollution. As the Fe-EDTA concentration increased, the conversion rate of hydrogen sulfide increased because of the high stability of Fe-EDTA complex. pH as an important environmental factor was 9.0 for the stability of chemical complex in the oxidation of hydrogen sulfide.

• Journal of the Korean Wood Science and Technology
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• v.44 no.1
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• pp.147-155
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• 2016

Pulp made from sugarcane bagasse (SCB) was bleached in element chlorine free (ECF) sequence. The peroxide bleaching process for the final bleaching process has been introduced in order to reduce the use of chlorine dioxide. Prior to peroxide bleaching, different chelating chemicals were applied. When 4.5% of the total chlorine dioxide was used, bleached SCB pulp using additional DTPA chelate stage (DEDQP) resulted in 87.0% of the ISO brightness. However, bleached pulp using simultaneous stage of DTPA chelate and chlorine dioxide (DE(DQ)P) was reached at 83.9% of the ISO brightness. The viscosity of DEDQP bleached pulp was 25.6 cPs, and the one of DE(DQ)P bleached pulp was 21.9 cPs. Decreasing of chelate effect by chlorine dioxide led to a decrease in the final brightness and a lower viscosity. But simultaneous stage of EDTA chelate and chlorine dioxide (DE(DQ)P) led to higher final brightness (87.0% ISO) and higher viscosity (25.8 cPs) than those of the $DEDQ_{EDTA}P$ bleached pulp (86.4% ISO, 25.2 cPs).

• Journal of the Korean Chemical Society
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• v.23 no.3
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• pp.141-151
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• 1979

The selective absorption of metal ions by chelating agent-loaded resins was studied in aqueous media. The resins were prepared by loading the conventional anion exchange resin, Dowex 1-X8 (50 to 100 mesh) with chelating agents containing sulfonic group, such as 8-hydroxy-quinoline-5-sulfonic acid (HQS) and 7-nitroso-8-hydroxyquinoline-5-sulfonic acid (NHQS). The stability of the resin was markedly influenced by the following factors; (1) the affinity and concentration of anions in the external solution, (2) the pH of the media. The optimum conditions for the absorption of metal ions were determined with respect to the pH, shaking time, and the effect of anion concentration in the medium. Under the optimum condition the order of the absorption of metal ions such as Fe(Ⅲ), Cu(Ⅱ), Pb(Ⅱ), and Zn(Ⅱ) was in accord with that of the stability constants of the chelates. The total capacities of the resins were found in the range of 0.6∼1.6 mmole metal per gram.

• Analytical Science and Technology
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• v.5 no.1
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• pp.63-71
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• 1992

Liquid chromatographic behavior of Pd(II), Ni(II) and Co(III) in N-Alkylisonitrosoacetylacetone imine(HIAA-NR) chelates was investigated by reversed phase high perfomance liquid chromatography. The optimum conditions for the separation of IAA-NR-metal chelates were examined respect to the flow rate and mobile phase strength. The metal-N-Alkylisonitrosoacetylacetone imine chelates in solution were successfully separated on Novapak $C_{18}$ column using acetonitrile/water mixture as mobile phase. The elution order of chelates is methyl>ethyl>propyl>butyl as N-alkyl group for ligand is varied. It was found that all IAA-NR-metal chelates were eluted in an acceptable range of capacity factor value($0{\leq}log\;k^{\prime}{\leq}1$). The dependence of log k' on the volume fraction of water in the binary mobile phase was examined. Also, the dependence of k' on the liquid-liquid extraction distribution ratio(Dc) in acetonitrile-water-alkane extraction system was investigated for IAA-NR-metal chelate. Both kinds of dependence are linear, which suggests that the retention of the electroneutral metal chelates on Novapak $C_{18}$ column is largely due to the hydrophobic effect.

• Current Research on Agriculture and Life Sciences
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• v.33 no.1
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• pp.1-5
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• 2015

This study investigated the chelation of a sorghum bran extract using iron (Fe) as a new natural colorant. The composition of the sorghum bran extract and chelation conditions were both examined. The thermal properties of the chelated colorants were analyzed using differential scanning calorimetry (DSC) and a thermal analyzer system(TGA). The sorghum bran extract solution showed a maximum absorbance at 281 nm based on UV/Vis spectrophotometry. According to the chelation pH conditions, pH 7.5 was the most effective. The chelation of the sorghum bran extract increased rapidly when increasing the iron concentration up to 2 mg/L, with no further chelation at a higher concentration. The particle size distribution curve for the chelated tannin revealed four groups: $4.5{\sim}17{\mu}m$, $20{\sim}42{\mu}m$, $45{\sim}80{\mu}m$, and $83{\sim}160{\mu}m$. In a DSC analysis, endothermic peaks attributed to the pyrolysis of the extract and chelated tannin were found at $318^{\circ}C$ and $415^{\circ}C$, respectively. In a TGA analysis, the chelation was shown to increase the final degradation temperature from $253^{\circ}C$ to $382^{\circ}C$, confirming that the chelation improved the thermal stability.

• Journal of the Korean Chemical Society
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• v.33 no.1
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• pp.113-119
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• 1989

Chelating resins containing hydrazide or triethylenetetramine side chain were prepared using a commercial cation exchage resin, Diaion WK 11, and their nitrogen contents were determined by elemental analysis. The synthesized resin, and commercial chelating resins, (Diaion-CR 10 and-CR 20) were treated with various metal chelates of which metal contents were subsequently determined by chelatometry. Sectioned beads of the resin-metal chelates were also observed using electron microprobs X-ray analyzer. To examine the catalytic activity of the resin-metal chelates, they were applied to the oxidation of various hydroxy compounds and l-ascorbic acid, and found to be effective catalysts.

• Applied Chemistry for Engineering
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• v.21 no.4
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• pp.396-400
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• 2010

In this work, the adsorption behaviors of activated carbons (ACs) containing chelating functional groups were studied in $CO_2$ removal. The ACs were modified by pyrolysis of peroxide and glycidyl methacrylate graft polymerization in order to induce chelating functional groups, such as diethylenetriamine groups on the AC surfaces. The surface functional groups of the ACs were characterized by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The textural properties of the ACs were analyzed by $N_2$/77 K isotherms. Adsorption behaviors of the ACs were observed in the amounts of $CO_2$ adsorption. From the results, we found that the chelating functional groups on the AC surfaces led to enhance selectivity and chemisorption on $CO_2$ adsorption in spite of decreasing the physical adsorption properties.

• Journal of the Korean Chemical Society
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• v.52 no.5
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• pp.515-522
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• 2008

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.949-954
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• 2012

This study is conducted to evaluate the effects of chelating agents for improving plant growth and reusing accumulated nutrients in soils of plastic film house. Two experiments were carried out at follows: i) The incubation test was conducted using soils treated with 0, 300 mM of EDTA and DTPA to examine the availability of nutrients. ii) For the pot test, chinese cabbages were cultivated in soils with 0, 0.1, 0.5, 1, and 5 mM of EDTA and DTPA to examine the impacts of plant growth response. The application of chelating agents increased ther availability of soil nutrients in the following order: DTPA > EDTA > control. Inorganic concentration of chinese cabbages in DTPA treatments consderably increased in nitrogen, phosphate, iron and aluminium contents than that of the other treatments. The optimal concentration of DTPA for vigorous plant growth as 0.5 mM. Thus, DTPA was more effective than other chelating agents for healty growth of cabbages and the availability of nutrients accumulated in plastic film house.

• Analytical Science and Technology
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• v.5 no.4
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• pp.389-399
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• 1992

Liquid Chromatographic behavior of Pd(II) in Isonitrosoethylacetoacetate lmine, $Pd(IEAA-NR)_2$ (R=H, $CH_3$, $C_2H_5$, $n-C_3H_7$, $C_6H_5-CH_2$, $n-C_4H_9$) chelates were investigated by reversed-phase HPLC on Micropak MCH-5 column using methanol/water as mobile phase. The optimum conditions for the separation of $Pd(IEAA-NR)_2$ chelates were examined with respect to the effect of the flow rate, sample solvent, mobile phase strength and column temperature. It wass found that metal chelates were properly eluted in an acceptable range of capacity factor value($0{\leq}log\;k^{\prime}{\leq}1$). The dependence of the logarithm of capacity factor(k') on the volume fraction of water in the binary mobile phase was examined. Also, the dependence of k' on the liquid-liquid extration distribution ratio($D_c$) in methanol-water/n-alkane extration system was investigated. Both kinds of dependence are linear, which susggests that the retention of the electroneutral metal chelate is largely due to the solvophobic effect. Standard adsorption enthalpy changes (${\Delta}H^{\circ}$) and standard adsorption entropy changes (${\Delta}S^{\circ}$) of Pd(II) Isonitrosoethylacetoacetate imine chelates on Micropak MCH-5 column were calculated by measuring capacity factor with changing temperature of the column.