• Journal of the Korean Society of Industry Convergence
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• v.6 no.3
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• pp.201-205
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• 2003

The effects of adsorption and desorption of alkali-metals on Si(111) surface were investigated by using AES and RHEED-system. The adsorption system is a fundamental interest because of its unique electronic properties such as measurement of work function change, adatom-core level shift. It was found that the growth node of K on Si(111) surface was layer by layer growth and the saturation coverage was 2.0ML at room temperature. Superstructure changes on Si(111) surface according to the alkali-metal thickness and substrate temperatures were accurately defined. By applying the isothermal desorption method, the desorption energies of Li/Si(111) and K/Si(111) surfaces was measured. On Li/Si(111) and K/Si(111) surfaces, the desorption energies were 3.07 eV, 2.19 eV respectively.

• Applied Chemistry for Engineering
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• v.7 no.4
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• pp.698-706
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• 1996

Dehydrogenation of methanol to produce formaldehyde was carried out over various silica-alumina catalysts doped with alkali metals in a continuous flow system. The reaction was rather dependent on Lewis acid than Br${\ddot{o}}$nsted acid suggesting that dehydrogenation of methanol was an electronic reaction. The Br${\ddot{o}}$nsted acid sites on silica-alumina were neutralized by doping with alkali metals, and the neutralization effect of Br${\ddot{o}}$nsted acid was dependent on the electron-donating capacity of the dopant metals. Activation energy for dehydrogenation of methanol decreased when Br${\ddot{o}}$nsted acid was neutralized by doping with K.

• Korean Journal of Environmental Agriculture
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• v.33 no.1
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• pp.1-8
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• 2014

BACKGROUND: Recent studies using many amendments for heavy metal stabilization in soil were conducted in order to find out new materials. But, the studies accounting for the use of appropriate amendments considering soil pH remain incomplete. The aim of this study was to investigate the effects of initial soil pH on the efficiency of various amendments. METHODS AND RESULTS: Acid soil and alkali soil contaminated with heavy metals were collected from the agricultural soils affected by the abandoned mine sites nearby. Three different types of amendments were selected with hypothesis being different in stabilization mechanisms; organic matter, lime stone and iron, and added with different combination. For determining the changes in the extractable heavy metals, water soluble, Mehlich-3, Toxicity Characteristic Leaching Procedure, Simple Bioavailability Extraction Test method were applied as chemical assessments for metal stabilization. For biological assessments, soil respiration and root elongation of bok choy (Brassica campestris ssp. Chinensis Jusl.) were determined. CONCLUSION: It was revealed that lime stone reduced heavy metal mobility in acid soil by increasing soil pH and iron was good at stabilizing heavy metals by supplying adsorption sites in alkali soil. Organic matter was a good source in terms of supplying nutrients, but it was concerning when accounting for increasing metal availability.

• Bulletin of the Korean Chemical Society
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• v.23 no.1
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• pp.59-64
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• 2002

A facile and precise batch oxidation reaction system allows continuous monitoring of the oxidation rate and cumulated oxygen conversion of xylenes, and the side reactions to carbon monoxide and carbon dioxide may also be studied. The oxidation reaction can be analyzed precisely with the rate and amount of oxygen consumed. The reaction reveals that 4-carboxybenzaldehyde is an unstable intermediate of p-xylene oxidation as the reaction proceeds instantaneously from p-toluic acid to TPA (terephthalic acid). The alkali metals accelerate oxidation, even though they retard the reaction initially. The oxidation rate increases with decreasing water concentration. However, in the later part of reaction, the reactivity decreases a bit if the water concentration is very low. This retarding effect of water can be overcome partly by the addition of potassium. The oxidation of o-xylene, compared with the oxidation of p-xylene and m-xylene, proceeds quite fast initially, however, the oxidation rate of xylene isomers in the later stage of reaction is in the order of p-xylene > mxylene > o-xylene.

• Journal of the Mineralogical Society of Korea
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• v.21 no.3
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• pp.261-269
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• 2008

A NYF-type (Nb-Y-Zr-F) Khaldzan-Buregtei pegmatite containing rare-earth metals occurs within alkali granitoid complex of the western Mongolia. The pegmatites are considered as differentiates of syenites and alkali feldpar granitic rocks, showing that their rare-earth element concentrations are enriched tens times higher than those from the adjacent alkali granitic rocks. It is suggested that econemic aspects of the pegmatites can be controlled by the magnitude of lateral and vertical extensions and local grade variation of REE-bearing pegmatites.

• Journal of Soil and Groundwater Environment
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• v.20 no.1
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• pp.7-18
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• 2015

The characteristics of As and heavy metals depend on the oxidation/reduction condition of the soil environment. The most heavy metals are immobilized by the reduction condition whereas As, Fe and Mn become more soluble. Therefore this study estimated the stabilization efficiency of the agricultural paddy soil in the vicinity of the abandoned mine using a flooded column test including analysis of the soil solution, contaminants fractionation and rice grain. Limestone and steelmaking slag were used as amendments for stabilization of the contaminated soil. In an analysis of the soil solution, the mobile characteristics of Fe and Mn, which were used as electron acceptors of the microorganisms, were controlled by increasing the pH by adding alkali amendments. This means that the contaminants combined with Fe and Mn can be stable under flooded reduction condition. However, the concentrations of cationic heavy metals (Cd, Pb, and Zn) were also decreased without amendments because the carbonates produced from microbial respiration increased the pH of the soil solution. In the amended soil, the specific sorbed fraction of As and carbonates fraction of heavy metals were increased when compared to the control soil at the end of the column test. Especially in heavy metals, the increase of carbonates fraction seems to be influenced by alkali amendments rather than microbial respiration. Because of the stabilization effect in the flooded paddy soil, the contents of As and Zn in rice grain from amended soil were lower than that of the control soil. But additional research is needed because of the relatively higher Pb content identified in the rice grain from the amended.

• Analytical Science and Technology
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• v.6 no.5
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• pp.471-477
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• 1993

The novel macrocylic ligand {(4, 5):(13, 14)-dibenzo-6, 9, 12-trioxa-3, 15, 21, -triazabicyclo [15. 3. 1]heneicosa-(1, 17, 19)(18, 20, 21) triene: HDBPDA} was synthesized, and protonable constants of the ligand and the complex stability constants with alkali metals alkaline earth metals were determined. We evaluated the resolution factor(${\Delta}$) from equation that inducing from stability constants(pK). Also, this ligand was grafted on chloromethylated styrene-divinyl benzene(Merrifield resin) for HDBPDA, ion exchanger. Alkali and alkaline earth metal ions were separated using water by the column chromatography with this ion exchanger. Selectivity(${\alpha}$) and resolution(Rs) of alkali and alkaline earth metal ions were measured from the elution curves chromatogram. The selectivity and resolution values of the various ions calculated from the elution curves were compared with those abtained from pK values. The results were in a good agreement between tow methods. Ion exchange capacity of the resin were determined using the alkali and alkaline earth metal ions and pH dependence of capacity was also discussed.

• Nuclear Engineering and Technology
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• v.55 no.2
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• pp.674-680
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• 2023

The brine and seawater are important and largely untapped sources of critical trace metals and elements. The coupling of selective recovery of trace metals from seawater/brine with desalination plants gives an added advantage of energy credits to desalination plants and as well as reduce the cost of desalinated water. In this paper, status review on recovery of important trace metals and other alkali metals from seawater is presented. The potential of Indian desalination plants for recovery of trace metals, based on recovery ratio of 0.35 is also highlighted. Studies carried out by the process based on adsorption using Radiation Induced Grafted (RIG) polymeric adsorbents and then fractional elutions are presented. The fouling factors due to bio fouling and dirt fouling have been estimated for various locations of interest through field trails. The pay loader in the form of compact Contactor Assembly with minimum pressure drop, for loading specially designed radiation grafted sorbent in leaflet form has been briefed, as required for plant scale facility. The typical conceptual process design details of farm assembly of project CRUDE are described.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1763-1768
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• 2006

Low work function alkali metals and alkaline earths successfully lower the electron injection barrier and increase electron injection into the organic layer in OLED displays, but their implementation is not easy. AlkaMax technology can ensure the required metal evaporation rate in a fast, homogeneous and easily controllable way.

• Bulletin of the Korean Chemical Society
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• v.31 no.3
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• pp.615-619
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• 2010

A new coumarin-thiazolobenzo-crown ether based fluorogenic chemosensor BTC (1) was reported. The ion-selective binding properties of 1 with different alkali, alkaline earth metals and transitional metals were investigated in an ethanol-DMSO system. BTC (1) showed the highest binding constant toward $Hg^{2+}$ over $Ag^+$, $Pb^{2+}$ and $Cu^{2+}$.