• 대한방사선방어학회:학술대회논문집
• /
• 2011.11a
• /
• pp.128-129
• /
• 2011

• Korean Chemical Engineering Research
• /
• v.50 no.2
• /
• pp.300-303
• /
• 2012

Phase change of calcium carbontae crystals in crystallization of precipitated calcium carbonate was researched by adding additives such as ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), citric acid (CIT) and pyromellitic amid (PMA). At low temperature $20^{\circ}C$, calcite crystal was made. At high temperature $80^{\circ}C$, aragonite crystal was made without additives. At middle temperature $40^{\circ}C$ and $60^{\circ}C$, Aragonite crystal also made by adding EDTA, DTPA. The crystal growth of Aragonite was retarded by the presence of CIT, PMA and the single phase of calcite was made. It was found that additives were important factors to make the single phase of calcium carbonate.

• Korean Chemical Engineering Research
• /
• v.43 no.2
• /
• pp.318-323
• /
• 2005

Supercritical water oxidation (SCWO, P>221 bar, T>$374^{\circ}C$) is a promising method for the decomposition of refractory organic compounds. In this study, the SCWO of Ethylenediaminetetraacetic acid (EDTA) was carried out in a tubular-type continusous reactor system with an $H_2O_2$ oxidant at $387-500^{\circ}C$, 250 bar and residence time (RT) of 15.9-88.9 s. The decomposition efficiencies increased with increasing temperature and oxidant amount, while it was inversely proportional to feed flow rate. The decomposition efficiency of 99.6% was obtained at $500^{\circ}C$, 250 bar, oxidant amount of 400% and residence time of 40.1 s. The effect of temperature on the decomposition efficiency was more significant than that of oxidant amount. In the case of the decomposition efficiency of 5,000 mg/L of EDTA (3,063 mg/L as $COD_{Cr}$), the decompostion of 99% or higher was obtained at the condition of over 40.1 s (RT) and 200 stoichiometric % of $H_2O_2$ in the supercritical water of $500^{\circ}C$ and 250 bar.

• Applied Chemistry for Engineering
• /
• v.10 no.1
• /
• pp.154-159
• /
• 1999

EDTA (ethylenediaminetetraacetic acid), a chelating agent is most widely used in industrial applications, especially for cleaning of metals in water, frequently prohibits metal removal from water in conventional water treatment technologies. It could be easier to remove aqueous metal ions by the breakdown of DETA complexed bonds first. This study investigated the availability of $TiO_2$ photo-catalysis for the aqueous phase oxidation of Cu(II)-EDTA, under an aerobic condition at $20^{\circ}C$ with $TiO_2$ (Degussa P-25) and 1.79mM of Cu(II)-EDTA. When $TiO_2$ loading was 2.0 g/L, the photo-catalytic oxidation of Cu(II)-EDTA was maximal. The tendency of EDTA adsorption onto the catalyst surface was affected by $TiO_2$ surface charge, and the oxidation rate of Cu(II)-EDTA by photo-catalysis was shown to be dependent upon the tendency of EDTA adsorption before photo-irradiation.

• Korean Chemical Engineering Research
• /
• v.51 no.6
• /
• pp.733-738
• /
• 2013

Sediment contains a high fraction of organic matter, high buffering capacity, and a large portion of fine grained particles such as silt and clay, which are major barriers to remove heavy metals from sediments. In this study, a lab-scale electrokinetic (EK) technique was applied to remove heavy metals effectively from marine sediment at a constant voltage gradient of 2 V/cm. A concentration of 0.1 M of ethylenediaminetetraacetic acid (EDTA), citric acid (CA), $HNO_3$, and HCl were circulated in the cathode, and tap water was circulated in the anode. CA extracted 92.4% of Ni, 96.1% of Cu, 97.1% of Zn, and 88.1% of Pb from marine sediment. A higher voltage gradient enhanced the transport of citrate and EDTA into the sediment and, therefore, increased metal extraction from the marine sediment through a complexation reaction between metals and the chelates. Based on these results, the electrokinetic process using a high voltage gradient with EDTA and CA might be useful to extract heavy metals from marine sediment.

• Journal of the Korean Chemical Society
• /
• v.27 no.2
• /
• pp.117-126
• /
• 1983

$^13C$ and $^51V$ NMR spectroscopy have been used to study the solution structures of the vanadium (v) complexes formed by ethylenediaminetetraacetic acid (EDTA), trans-cyclohexanediaminetetraacetic acid (CDTA), 1,2-propylenediaminetetraacetic acid (PDTA), ethylenediaminediacetic acid (EDDA), 2-hydroxyethylethylenediaminetriacetic acid (HEDTA), diethylenetriaminepentacetic acid (DPTA), and nitrilotriacetic acid (NTA). All of the complexes probably have octahedral structures containiing cis-$VO_2$ core. The coordination of hydroxylethyl group is found to be less favored than that of acetate group. EDDA forms two isomers, ${\alpha}$-cis and ${\beta}$-cis. PDTA also forms two structural isomers due to the methyl group in the ligand.

• Korean Journal of Soil Science and Fertilizer
• /
• v.48 no.6
• /
• pp.634-640
• /
• 2015

Chelating agents have been proposed to improve the efficiency of phytoextraction of heavy metal hyperaccumulator. However, little studies to elucidate mechanism of chelating agents to increase cadmium (Cd) extractability have been conducted. The objectives of this study were to evaluate effect of different chelating agents on Cd extractability and to determine mechanism of Cd mobilization affected by these agents. An arable soil was spiked with inorganic Cd ($CdCl_2$) to give a total Cd concentration of $20mgCdkg^{-1}$. Ethylenediaminetetraacetic acid (EDTA) and citric acid (CA) were selected and mixed with the arable soil at the rates of 0 and $5mmolkg^{-1}$. The mixture soils were incubated at $25^{\circ}C$ for 4 weeks in dark condition. Concentration of F1 Cd fractions (water soluble) significantly increased with addition of EDTA but did not changed with addition of CA. Especially; concentration of F5 Cd fractions (residual) significantly increased with addition of CA. Increase in water soluble with EDTA might be attributed to complexation of Cd and EDTA. Dissolved organic carbon concentration significantly increased with EDTA addition, but did not with CA implying that considerable amount of CA was decomposed to inorganic carbon by microorganism. Log activity of carbonate ($CO_3{^{2-}}$) which might be generated from CA increased with addition of CA. Increase in residual Cd fraction might be due to precipitation of Cd as $CdCO_3$. As a result, EDTA was effective in increasing Cd extractability, by contrast CA had significant effect in reducing Cd extractability.

• Economic and Environmental Geology
• /
• v.43 no.2
• /
• pp.101-107
• /
• 2010

In order to deal with the problem that phytoremediation takes long time in achieving the practical effect, the enhanced phytoremediation by Barnyard grass (Echinochloa crus-galli) was conducted. In addition, we examined the synergistic effect by adding PSM (phosphate -solubilizing microbes) and EDTA (ethylenediaminetetraacetic acid) to the arsenic contaminated soil in the vicinity of the abandoned mine. The removal efficiency of arsenic in the site with PSM application increased about 16% when compared to control site, which was due to increase of plant biomass. The EDTA has been successfully utilized in respect of enhanced mobility and solubility of arsenic in the soil. As a result, BF (bioaccumulation factor) significantly increased but the inhibition of plant growth resulted in 20% reduction of arsenic removal efficiency. The application of PSM and EDTA may enhance the efficiency of phytoremediation. However, the time and method of EDTA application should be further examined to reach the maximum removal efficiency.

• Applied Chemistry for Engineering
• /
• v.34 no.3
• /
• pp.279-284
• /
• 2023

Isothermal titration calorimetry (ITC) is a useful technique to obtain thermodynamic binding properties such as enthalpy, Gibbs free energy, entropy, and stoichiometry of the chelation reaction. A single independent binding site model was used to evaluate the thermodynamic binding properties in BaCl₂ and ethylenediaminetetraacetic acid (EDTA) in Trince and HEPES buffers. ITC enables us to elucidate the binding mechanism and find an optimal chelation condition for BaCl₂ and EDTA in the pH range of 7~11. Chelation of BaCl₂ and EDTA is a spontaneous endothermic reaction. As pH increased, entropic contributions dominated. The optimal pH range is narrow around pH 9.0, where 1:1 binding between BaCl₂ and EDTA occurs.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.13 no.4
• /
• pp.153-156
• /
• 2003

Pure and Ethylenediaminetetraacetic acid (EDTA) doped L-arginine phosphate (LAP) single crystals were grown from the aqueous solution by temperature lowering method. The effect of EDTA additive on the solubility and metastable zone width of LAP solution has been investigated. Addition of EDTA has enhanced the metastable zone width of LAP and hence bulk crystals could be grown. The growth rate along the [100] direction increases with EDTA additive. Powder X-ray diffraction and FTIR studies reveal the absence of EDTA in the lattice of LAP, This reveals that the addition of EDTA to LAP doesn't influence the crystallinity. However, the transmittance and NLO properties significantly increase with EDTA additive and hence bulk LAP crystals are useful for laser fusion experiments.