• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 춘계학술논문요약집
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• pp.183-183
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• 2018

In this study, 5-bromo-2,9-bis(5,6-diphenyl-1,2,4-triazin-3-yl)-1,10-phenanthroline (5-bromo-Ph4-BTPhen) was synthesized and evaluated for its ability to remove major radionuclides ($Cs^+$, $Sr^{2+}$, and $Co^{2+}$). The synthesized ligand removed both $Sr^{2+}$ and $Co^{2+}$ from $1mg\;L^{-1}$ aqueous solutions with extraction efficiencies of up to 99% at neutral and alkaline pH. The $Sr^{2+}$ and $Co^{2+}$ removal efficiencies decreased as a consequence of the higher bonding strengths of competing metal ions to the N-donor atoms in the cavity of the ligand; competing divalent ions affected the $Sr^{2+}$ and $Co^{2+}$ removal efficiencies more than monovalent ions.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2003년도 International Symposium on Clean Environment
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• pp.61-64
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• 2003

This study was conducted to investigate the chemical characteristics of $PM^{10}$ at Anmyeon-do during the periods from January 1998 to December 2001. The $PM^{10}$ samples ($PM^{10}$) were collected by High Volume Air sampler (HVAS). The measured items were mass concentration of $PM^{10}$ with the major ions ($Cl^{-}$, ${SO_{4}}^{2-}$, ${NO_3}^{-}$, ${Mg}^{2+}$, ${Ca}^{2+}$, ${K}^{+}$etc.) and metallic elements (AI, Fe, Mn, Cr, Zn, Pb etc.). The chemical analysis of major ion components were made by Ion Chromatography (DX-500) and that of metallic elements were made by Inductively Coupled Plasma Spectrometer (ICP-AES, ICP-Mass). The average mass concentration of $PM^{10}$ increased substantially during the heavy dust periods (Asian Dust cases). For water-soluble ions, concentrations of ${Ca}^{2+}$, ${SO_{4}}^{2-}$ and ${NO_3}^{-}$ were remarkably enhanced. Concentrations and mass fraction of crustal elements such as Na, Mg, Ca, Fe, Mn were highly elevated, but those of pollution-derived heavy metals were appreciably decreased. The factor analysis was conducted in order to make the large and diverse data set as manageable levels and to qualitatively examine the relationship between the variables.

• 한국대기환경학회지
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• 제12권4호
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• pp.399-406
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• 1996

Acidic fog is catastrophic to aviation and potentially affect materials, vegetation, crops and public health. This paper was carried out to investigate the chemical features of fog sample at Mt. Sobaek (mean sea level : 1, 340m) from June to August 1995. Each sample was analyzed for pH, electrical conductivity and major ions (anion : $Cl^N)_3^-, SO_4^{2-}, cation : Na^+, NH_4^+, K^+, Mg^{2+}, Ca^{2+}$) by ion chromatography. The quality analysis of fog sample data was performed based on ion balance and electrical conductivity method. The wind directions are subdivided into the northerly and southerly wind according to the wind direction data at the Sobaek-san meteorological observation station. Statistical analyses were performed on the complete set of results in order to obtain a description of fog sample. All the statistical treatment was carried out using the SPSS/PC + software package. The major ion concentration of fog samples was higher for the northwesterly wind cases than sourtheasterly wind cases. The pH of fog sample varied between 2.95 and 6.08. The average pH and electrical conductivity of total sample (n=210) were 4.39 and 113.0 $\mu$S/cm, respectively. It may be noted that in nearly all the cases, the dominant major ions in the fog sample at Mt. Sobaek were $SO_4^{2-}, NO_3^-, H^+ and NH_4^+$.

• Nuclear Engineering and Technology
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• 제52권2호
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• pp.328-336
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• 2020

Cesium is a major product of uranium fission, which is the most commonly existed radionuclide in radioactive wastes. Various technologies have been applied to separate radioactive cesium from radioactive wastes, such as chemical precipitation, solvent extraction, membrane separation and adsorption. Crown ethers and calixarenes derivatives can selectively coordinate with cesium ions by ion-dipole interaction or cation-π interaction, which are promising extractants for cesium ions due to their promising coordinating structure. This review systematically summarized and analyzed the recent advances in the crown ethers and calixarenes derivatives for cesium separation, especially focusing on the adsorbents based on extractants for cesium removal from aqueous solution, such as the grafting coordinating groups (e.g. crown ether and calixarenes) and coordinating polymers (e.g. MOFs) due to their unique coordination ability and selectivity for cesium ions. These adsorbents combined the advantages of extraction and adsorption methods and showed high adsorption capacity for cesium ions, which are promising for cesium separation The key restraints for cesium separation, as well as the newest progress of the adsorbents for cesium separation were also discussed. Finally, some concluding remarks and suggestions for future researches were proposed.

• Current Photovoltaic Research
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• 제2권2호
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• pp.53-58
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• 2014

$Tb^{3+}$ - or $Ce^{3+}$-doped $LaBO_3$ phosphors were synthesized by a solid-state reaction process with different concentrations of activator ions. The XRD spectra showed the monoclinic $LaBO_3$ pattern with the main peak occurring at (014) plane, irrespective of the kind of activator ions. The crystallite size was determined by using the Scherrer formula, and the maximum was obtained with an activator concentration of 0.05 mol for both phosphors. The emission spectra of $LaBO_3$ phosphors doped with $Tb^{3+}$ ions under excitation at 269 nm exhibited three major emission bands at 488, 544, and 587 nm. The strongest emission was green at 544 nm owing to the $^5D_4-^7F_5$ transition at a $Tb^{3+}$ ion concentration of 0.05 mol. For the $Ce^{3+}$-doped $LaBO_3$ phosphors, one strong blue band centered at 469 nm and weak multipeaks were observed. These results suggest that the optimum green and blue emission can be realized by controlling the concentration and type of activator ions incorporated in the host crystal.

• 자원환경지질
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• 제28권3호
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• pp.231-241
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• 1995

It is well known that hydroxyapatite [$Ca_{10}(PO_4)_6(OH)_2$] have an exchangeability for various heavy metal ions in aqueous solution. To evalute the feasibility of employing the synthetic hydroxyapatites as an eliminatable exchanger for environmentally noxious caions in waste water, the adsorption properties, the removal capacities and the selectivity of the apatites for various cations were investigated in more detailed. The heavy metal cations have been exchanged in calcium part of hydroxyapatite. The order of the degree of amount exchanged of the investigated cations is $Pb^{2+}>Cd^{2+}>Zn^{2+}>Ba^{2+}$. The molar ratios between released $Cd^{2+}$ ions and remeved divalent metal cations in the reacted solution with hydroxyapatite are roughly close to an integer 1.0, suggesting that an ion-exchange reaction could have played a major role in the removal of heavy metals rather then an adsorption effect. The exchangeability of the hydroxyapatite powder of Ca/P molar ratio 1.67, which have specipic surface area of $104.5m^2g^{-1}$, appeared to be better then $237.6{\mu}g$ per g for $Pb^{2+}$ ions. The removal capacity of the heavy metal ions varies directly as particle size of hydroxyapatites. All evidences obtained indicate that the synthesized hydroxyapatite powders by precipitation reaction method can be employed as an effective cation exchanger for eliminating noxious ions in waste water even in some improvemental.

• Bulletin of the Korean Chemical Society
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• 제12권2호
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• pp.130-137
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• 1991

The following new cryptand 221 complexes of lanthanides(Ⅲ) and dioxouranium(Ⅵ) nitrate have been synthesized: $(Ln(C_{16}H_{32}N_2O_5)(H_2O)_2(NO_3)_3\ and \((UO_2)_2(C_{16}H_{32}N_2O_5)(H_2O)_4(NO_3)_4$. These complexes have been identified by elemental analysis, moisture titration, conductivity measurements and various spectroscopic techniques. The proton and carbon-13 NMR as well as calorimetric measurements were used to study the interaction of cryptand 221 with La(Ⅲ), Pr(Ⅲ ), Ho(Ⅲ) and $UO_2(Ⅱ)$ ions in nonaqueous solvents. The bands of metal-oxygen atoms, metal-nitrogen atoms and O-U-O in the IR spectra shift upon complexation to lower frequencies, and the vibrational spectra ({\delta}NMN$) of metal-amide complexes in the crystalline state exhibit lattice vibrations below 300 $cm^{-1}$. The NMR spectra of the lanthanides(Ⅲ) and dioxouranium(Ⅵ) nitrate complexes in nonaqueous solvents are quite different, indicating that the ligand exists in different conformation, and also the $^1H$ and $^{13}C-NMR$ studies indicated that the nitrogen atom of the ring has greater affinity to metal ions than does the oxygen atom, and the planalities of the ring are lost by complexation with metal ions. Calorimetric measurements show that cryptand 221 forms more stable complexes with $La^{3+}$ and $Pr^{3+}$ ions than with $UO^{22+}$ ion, and $La^{3+}/Pr^{3+}$ and $UO^{22+}/Pr^{3+}$ selectivity depends on the solvents. These changes on the stabilities are dependent on the basicity of the ligand and the size of the metal ions. The absorption band (230-260 nm) of the complex which arises from the direct interaction of macrocyclic donor atoms with the metal ion is due to n-{\delta}*$ transition and also that (640-675 nm) of $UO^{22+}$-cryptand 221 complex, which arises from interaction between two-dioxouranium(Ⅵ) ions in being out of cavity of the ligand ring is due to d-d* transition.

• Asian Journal of Atmospheric Environment
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• 제10권2호
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• pp.57-66
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• 2016

Wet deposition fluxes of ions at a coastal site in southwestern Japan in the period 1996-2003 were investigated to quantify the respective contributions of cyclone-, stationary front- and typhoon-associated rains. On average, the deposition fluxes of terrigenous-origin ions, nss-$SO_4{^{2-}}$, $NO_3{^-}$, $NH_4{^+}$ and nss-$Ca^{2+}$ were $37.6{\pm}7.3$, $16.3{\pm}4.2$, $19.0{\pm}3.4$ and $9.6{\pm}4.8meq\;m^{-2}yr^{-1}$, and those of $Na^+$ and $Cl^-$, the major ions in sea water, were $97.0{\pm}38.2$ and $115.2{\pm}48.2meq\;m^{-2}yr^{-1}$, respectively. Cyclone-associated rain constituted more than 50% of the fluxes of the terrigenous ions in almost all years. Stationary front-associated rain also contributed significantly, although the contribution was lower than the contribution by Cyclone-associated rain in almost all years. In particular, the wet deposition flux of nitrogen compounds of $NO_3{^-}$ and $NH_4{^+}$, which are important nutrients for micro-bioactivities in sea surface water, was dominated by cyclone-associated rain. Due to the extreme abundance of $Na^+$ and $Cl^-$ in the rainwater of typhoons, the fluxes of $Na^+$ and $Cl^-$ were contributed substantially by typhoons in years with typhoons' passage although cyclones were still the largest contributor to the fluxes. These results indicate the dominance of cyclones in the wet deposition to the East China Sea areas and the necessity to take rain types into account for a more accurate elucidation of the temporal and spatial variation of the wet deposition.

• 한국환경과학회지
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• 제7권5호
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• pp.707-716
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• 1998

The chemical characteristics of precipitation was investigated in Pusan area. Samples were collected from January to November in 1996 at 4 sites, and analyzed pH, major soluble ionic components(C $l^{[-10]}$ , N $O_3$$^{[-10]}$ , S $O_4$$^{2-}$, N $a^{+}$, $K^{+}$, N $H_4$$^{+}$, $Mg^{2+}$, $Ca^{2+}$). The order of anion and cation concentrations for the initial precipitation were C $l^{[-10]}$ ＞ S $O_4$$^{2-}$ ＞ N $O_3$$^{[-10]}$ , and $Ca^{2+}$ ＞ N $a^{+}$ ＞ N $H_4$$^{+}$ ＞ $Mg^{2+}$ ＞ $K^{+}$, respectively. At coastal sites(P1 and P2) C $l^{[-10]}$ and N $a^{+}$ of maritime sources (seasalt) were high, but at inland sites(P3 and P4) nss-C $a^{2+}$ and nss-S $O_4$$^{2-}$ were high. Calcium ion for the initial precipitation showed high value of enrichement factor(EF) relative to seawater composition. The contribution of seasalt to the composition of precipitation was higher at bite P1 (53.5%) than those of the other sites. Throughout the year the concentrations of major ions for the initial precipitation were low in the heavy rain season. The mean pH for the initial precipitation was 5.4 and showed the negative relationship with the precipitaion amount. The S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ do not play an important role in rain acidification due to the high(97%) neutralizing effect of amonia and calcium species.and calcium species.

• 한국대기환경학회지
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• 제14권2호
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• pp.143-152
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• 1998

The aerosol concentrations of ionic components were measured on a daily basis from a coastal monitoring site located at Kosan, Cheju Island from 26 September to 5 October 1997 as a field-intensive for a LRTAP project The chemical species we investigated include most of important inorganic species (i.e., Cl-, NO3-, F-, SO42-, Na+, NH4+, and K+) and some organic species (i.e. formats, acetate, and methanesulfonate (MSA) ions). The concentration data of those important inorganic and organic species obtained during this study were evaluated to properly address their chemical and physical characteristics. Most of major inorganic components including sulfate, sodium, chloride, and potassium ions exhibited very conservative relationships with each other such that the concentration ratios of any pair are quite analogous to that of seawater ratio. Since the oceans serve as the major sources of ionic constituents, their concentration changes appear to be senstively reflected by the factors affecting air-sea processes such as an increase in wind speed or changes in wind direction. A comparative analysis of sulfur-containing species such as seasalt (SS) and nonseasalt (NSS) sulfate and MSA were also made to assess the factors influencing the S cycling. An evaluation of NSS/SS ratios suggests that most of sulfate be associated with NSS fraction rather than 55 one. The finding of lower MSA/NSS-SO42- ratio along with a line of physical evidence such as intrusion of anthropogenically affected air mass suggests that the oxidation of S species have been promoted under the conditions encountered during the study period. Finally, the concentration data of carboxylic species (such as formats and acetate ions) were also analyzed. Although the existence of temporal trends were difficult to assess, these data indicate that their contribution to the precipitation acidity may not be significant enough.