• Bulletin of the Korean Chemical Society
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• v.33 no.6
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• pp.1845-1850
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• 2012

Layered metal hydroxides (LMHs) containing calcium were synthesized by coprecipitation in solution having two different trivalent metal ions, iron and aluminum. Two mixed metal solutions ($Ca^{2+}/Al^{3+}$ and $Ca^{2+}/Fe^{3+}$ = 2/1) were added to sodium hydroxide solution and the final pH was adjusted to ~11.5 and ~13 for CaAl-and CaFe-LMHs. Powder X-ray diffraction (XRD) for the two LMH samples showed well developed ($00l$) diffractions indicating 2-dimensional crystal structure of the synthesized LMHs. Rietveld refinement of the X-ray diffraction pattern, the local structure analysis through X-ray absorption spectroscopy, and thermal analysis also confirmed that the synthesized precipitates show typical structure of LMHs. The chemical formulae, $Ca_{2.04}Al_1(OH)_6(NO_3){\cdot}5.25H_2O$ and $Ca_{2.01}Fe_1(OH)_6(NO_3){\cdot}4.75H_2O$ were determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Particle morphology and thermal behavior for the synthesized LMHs were examined by field emission scanning electron microscopy and thermogravimetricdifferential scanning calorimetry.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.275-278
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• 2002

In this study, to increase removal efficiency of traditional electrokinetic treatment and to reduce contaminant load of wastewater that discharged through cathode compartment, enhanced electrode compartments were investigated. Hydroxide precipitation near the cathode electrode that encounter during traditional electrokinetic treatment were prevented by enhanced electrokinetic remediation test with newly invented electrode compartment. And heavy metal concentration in wastewater showed 0 ppm thus, additive post-treatment cost were not needed.

• Journal of Integrative Natural Science
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• v.2 no.3
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• pp.198-201
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• 2009

Dithiocarbamoic acid and their derivatives were found to readily react with potassium and sodium hydroxide to give the corresponding alkali metal dithiocarbamoic acid derivatives 8-17 in moderate to good yields.

• Bulletin of the Korean Chemical Society
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• v.16 no.5
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• pp.422-427
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• 1995

In a stream of water sample, trace metal ions are quantitatively coprecipitated with Indium hydroxide and filtered. The filtered precipitate is continuously dissolved in 3 M nitric acid and introduced to ICP directly. The lead, cadmium, and copper are concentrated more than 10-fold and determined with ICP-AES at a sampling frequency of 10/hour. The detection limits are 2.89, 1.43,0.52 ppb for lead, cadmium, and copper respectively. Recoveries of lead, cadmium, and copper are 98.7, 94.3, and 104.5% respectively. The RSD values for three elements are about 3-5% currently.

• Journal of the Korean Chemical Society
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• v.38 no.2
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• pp.129-135
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• 1994

Acyclic polyether dicarboxylic acid have been studied as metal cation carriers in a bulk liquid membrane system. The proton-ionizable ligands feature allows the coupling of a cation transport to reverse proton transport. This feature offers promise for the effective separation and concentration of metal cations with the metal cation transport being driven by a pH gradient. Metal cation transport increased regularly with increasing hydroxide($H^-$) concentration of source phase and with proton($H^+$) concentration of receiving phase. Competitive transport by the acyclic polyether dicarboxylic acids is selective for calcium ion over other alkaline-earth cations.

• Resources Recycling
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• v.21 no.4
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• pp.35-43
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• 2012

This study was carried out for the purpose of obtaining basic data to utilize the AMD sludge as sorbent for heavy metal ions. The sludge from the treatment process of Acid Mine Drainage mainly consists of fine iron hydroxide or iron oxide hydrate and calcite, and the fine iron hydroxide or iron oxide hydrate has a property of adsorbing heavy metal ions. In this study, we investigated the physical property of the AMD sludge like as mineral composition, particle size and shape and chemical composition and also investigated the influence of dosage of sludge, adsorbing time, pH, initial concentration and sintering temperature on the adsorption of heavy metal ions.

• Journal of the Korean Wood Science and Technology
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• v.27 no.1
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• pp.18-23
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• 1999

The formation conditions of Na-cellulose II with three fold helix were investigated by an x-ray diffraction method. Na-cellulose II was formed through Na-cellulose I. It seems that the concentration of sodium hydroxide in Na-cellulose II is higher than both those of Na-cellulose I and Na-cellulose III. Na-cellulose II was formed well by different rinsing and drying methods even though the sample treatment was carried out in very short periods of time. Metal-complexed Na-cellulose swollen in the mixture of $Cu(OH)_2$ and sodium hydroxide is stable in wet state, and changed to a different polymorph by drying.

• Resources Recycling
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• v.3 no.1
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• pp.9-16
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• 1994

Fine cobalt metal powders was produced from domestic Stellite scrap by decomposing it with molten sodium hydroxide. Complete decomposition of the scrap could be obtained with the weigth ratio of sodium hydroxide to Stellite being about 2 at the temperature ranges of $750~800^{\circ}C$ for an hour. The cobalt-bearing compound was identified as $Co_2O_3{\dot}H_2O$ by X-ray analysis and D.T.-T.G.a.. The compound was then digested in HCI to form cobalt chloride, and after iron removal by adjusting the pH of the solution, cobaltous or cobaltic hydroxide was precipitated at the pH of about 13 or 4, respectively. The precipitates were reduced by hydrogen in the temperatures of $400~500^{\circ}C$ to fine cobalt powders of high purity with the size of 1.0 to $1.5\mu\textrm{m}$. The recovery of cobalt from Stellite scrap was about 75~86% by weight.

• Economic and Environmental Geology
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• v.42 no.6
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• pp.549-559
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• 2009

The objectives of this study are to investigate the biomineralization of goethite and lepidocrocite formed on the twisted-stalk and the sheathed-filament structure that is suggest microbe origin, and heavy metal in the yellow Fe-hydroxide. On the ratio of Cl and the Cl/Br ratios that are a pollution and non-pollution of groundwaters, it is indicated that the groundwater in this areas were relatively contaminated by human activity. The composition of the yellow Fe-hydroxide consisted mainly of $Fe_2O_3$ and $SiO_2$. The content of $Fe_2O_3$ ranges from 58.57 wt.% to 75.7 3wt.%, and $SiO_2$ content ranges from 5.8 wt.% to 16.17 wt.%. Heavy metal elements such as Zn(max. 6,160 mg/kg), Pb(max. 377 mg/kg), U(max. 503 mg/kg), Cr(max. 203 mg/kg), Cu(max. 77 mg/kg), V(max. 162 mg/kg), Ni(max. 105 mg/kg) were observed to be rich in those yellow Fe-hydroxide. The lath and platy crystals and needle-shaped crystals were clearly observed on the twisted-stalks and sheathed-filaments structure. The goethite, gypsum, and lepidocrocite were identified in the yellow Fe-hydroxide by x-ray powder diffraction.

• Journal of the Korean Wood Science and Technology
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• v.12 no.3
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• pp.9-14
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• 1984

The removal and readsorption effects of pine and oak bark grown in Korea on water pollution caused by heavy metal ions have been investigated. Bark saturated with heavy metal ions is refleshed with 0.1 N ammonium acetate and then its readsorption has been done. The results obtained are as follows: 1. Adsorption effect of pine bark is similiar to that of oak bark, and 20-40 meshed bark gives the best results. 2. 0.1 N amonium acetate of pH 7 shows more elutriative than the others such as pH 3 hydrochloric acid, pH 10 ammonium hydroxide and pH 7 water. 3 Pine bark refleshed with 0.1 N ammonium acetate gets two times as effective in adsorption as raw bark, and shows more effective than oak bark.