• Journal of Soil and Groundwater Environment
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• v.11 no.1
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• pp.14-22
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• 2006

Laboratory column experiment for simultaneous removal of Cd and Cr(VI) were conducted using newly developed material of Fe-loaded zeolite having both reduction ability and sorption capacity. The solution containing Cd and Cr(VI) was injected into the column and the breakthrough curves (BTCs) for the contaminants were observed at the effluent port. Cd breakthrough was not initialized until Cr(VI) breakthrough was completed. Therefore it could be concluded that overall efficiency of Fe-loaded zeolite should be determined by the reactivity for Cr(VI). The relative concentration of Cr(VI) BTC increased to the unit value while initial breakthrough was delayed and the propagation of breakthrough was slowed. In order to quantitatively describe the shape of Cr(VI) BTC, new parameters of ${\alpha}\;and\;{\beta}$ designated to be shape parameters, were defined and applied in contaminant transport concentration. These parameters were employed to represent the degree of initial breakthrough delay and the degree of breakthrough propagation, respectively. As initial contaminant concentration increased, ${\alpha}$ decreased, which indicated the delay of BTC's initiation. And as initial contaminant flow rate increased, ${\beta}$ decreased, which represented the faster propagation of the BTC. From these results, Fe-loaded zeolite was found to be an effective reactive material for PRBs against heavy metals having different ionic forms in groundwater. And it could be expected that as groundwater flows faster, the propagation of breakthrough would be faster and as contaminant concentration is higher, the initial point of breakthrough would appear earlier.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.151-154
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• 2005

Laboratory column experiments for simultaneous removal of Cd and Cr(VI) are conducted using newly developed material, referred to as Fe-loaded zeolite, which has both reduction ability of iron and ion exchange ability of zeolite. Breakthrough curves were obtained from each column experiment, and described with advection-dispersion equation. Apparent parameters including $K_{app}\;and\;D_{app}$ were newly introduced for effectively describing the Cr(VI) breakthrough curve. $K_{app}$ decreased with increasing initial contaminant concentration and with decreasing flow rates. Whereas, $D_{app}$ were not significantly affected by initial contaminant concentration or flow rate.

• Journal of the Korean Geotechnical Society
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• v.26 no.10
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• pp.61-68
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• 2010

A pilot-scale model test was performed to estimate the availability of new material, Fe-loaded zeolite, as the filling material in permeable reactive barrier (PRB) against the contaminated groundwater with both Cd and Cr(VI). Aquifer was simulated by filling up a large scale soil tank with sands, and mobilizing the water flow by the head difference of water level in both ends of the tank. Then, the mixture of concentrated Cd and Cr(VI) solution was injected into the aquifer to form a contaminant plume, and its behavior through Fe-loaded zeolite barrier was monitored. The test results showed that Fe-loaded zeolite barrier successfully treated the contaminant plume containing both Cd and Cr(VI) and that the immobilized contaminants in the barrier were not desorbed or released. The results indicated that the Fe-loaded zeolite could be a promising material in PRBs against the multiple contaminants with different ionic forms like Cr(VI) and Cd.

• Journal of Environmental Health Sciences
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• v.27 no.3
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• pp.107-112
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• 2001

This work reports the application of a hollow fiber module(HFM) for Cr(VI) extraction from heavy metal salts mixed solution by using microporous hydrophobic hollow fiber module. In HFM configuration, the organic extraction used for the extraction of Cr(VI) was di-(2-ethyl hexyl) phosphoric acid(D2EHPA) diluted with n-heptane. The study of HFM includes the influence of hydrodynamic and chemical condition, i.e., the flow rate of feed solution, the time of reactive extraction, the concentration of feed solution, and the pH of aqueous phase solutions. Several experiments with synthetic solution of different mixed components system of Cr(VI) solutions established optimum condition to achieve a clean separation of Cr(VI). It was possible to separate Cr(VI) in the presence of metal salts mixed solution, such as Zn(II), Ni(II), Cu(II), and Cd(II) using the HFM technique.

• Korean Journal of Environmental Biology
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• v.25 no.4
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• pp.313-318
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• 2007

Monitoring for the quality of coastal water is necessary to improve its biological resources and to maintain healthy environments. We measured the concentrations of phenols, nine polychlorinated biphenyls (PCBs), tributyltin (TBT) in surface water at 5 stations and the concentrations of mercury (Hg), chromium (Cr (VI)), cadmium (Cd), lead (Pb) in surface water of 10 stations in Tongyeong marine ranching ground of Korea in August, 2003. The concentrations of analytes were determined as follows: phenols: 1.6$\sim$2.8 ppb, PCBs: not detected (ND), Hg: <0.1 ppb, Cr (VI): 0.01$\sim$5.32 ppb, Cd: ND$\sim$0.41 ppb and Pb: 0.43$\sim$2.60 ppb. These concentrations satisfied the standards of human health protection in coastal water by Ministry of Environment, Republic of Korea as follows: phenols; 5 ppb, PCBs: 0.5 ppb, Hg: 0.5 ppb, Cr (VI): 50 ppb, Cd: 10 ppb and Pb: 50 ppb. TBT was not listed in the standards. The concentrations of Sn in TBT analyzed in sea water of Tongyeong marine ranching ground were in the range of ND$\sim$0.0273 ppb which are similar with the values of 8$\sim$35 ng Sn $L^{-1}$ (0.008$\sim$0.035 ppb) in Chinhae Bay studied by Shim et al.. Therefore, the quality of sea water in Tongyeong marine ranching ground was safe enough to protect human health.

• Analytical Science and Technology
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• v.17 no.3
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• pp.199-210
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• 2004

A new polystyrene-divinylbenzene chelating resin containing 4,5-dihydroxy-naphthalene-2,7-disulfonic acid (chromotropic acid : CTA) as functional group has been synthesized and characterized. The sorption and desorption properties of this chelating resin for Cr(III) ion and Cr(VI) ion including nine metal bloodstain. As a results, FOB test kit could be effectively applied to identification of human blood at chelating resin was stable in acidic and alkaline solution. The Cr(VI) ion is selectively separated from Cr (III) ion at pH 2 and the maximum sorption capacity of Cr(VI) ion is 1.2 mmol/g. In the presence of anions such as $F^-$, $SO{_4}^{2-}$, $CN^-$, $CH_3COO^-$, $NO{_3}^-$, the sorption of Cr(VI) ion was reduced but anions such as $PO{_4}^{3-}$ and $Cl^-$ revealed no interference effect. The elution order of metal ions obtained from breakthrough capacity and overall capacity at pH 2 was Cr(VI)>Sn(II)>Fe(III)>Cu(II)>Cd(II)${\simeq}Pb(II){\simeq}Cr(III){\simeq}Mn(II){\simeq}Ni(II){\simeq}Al(III)$. Desorption characteristics for Cr(VI) ion was investigated with desorption agents such as $HNO_3$, HCl, and $H_2SO_4$. It was found that the ion showed high desorption efficiency with 3 M HCl. As the result, the chelating resin, XAD-16-CTA was successfully applied to separation and preconcentration of Cr (VI) ion from several metal ions in metal finishing works.

• Journal of the Korean Chemical Society
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• v.43 no.4
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• pp.407-411
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• 1999

Studies have been carried out on the fabrication of PPy/GC and PPy/Pt electrode modified with polypyrrole film and determination of Cr(VI) by using 3-electrode system with modified electrodes. Modified electrodes were able to easily fabricated by cyclic voltammetry scanned from +1.0V to -1.0V(vs. Ag/AgCl) at 50 mV/sec. Film thickness could be controlled at same condition by the number of cycling up to 26 times. Reduction behaviour of Cr(VI) at PPy/GC electrode could be seen at wide potential ranges from +0.6V to -0.5V(vs. Ag/AgCl), and maximum reduction peak potential of the ion was observed at -0.25V(vs.Ag/AgCl). Calibration graph at its potential was linear from 0.1 ppm to 80.O ppm. Slope factor and relative coefficient were 1.75 mA/ppm and 0.998, respectively. Reduction behaviour of Cr(VI) at PPy/Pt electrode was similar to PPy/GC electrode, Calibration graph was linear from l.0 ppm to 60.0 ppm. Slope factor and relative coefficient were 0.5mA/ppm and 0.923, respectively. But PPy/GC modified electrode had about 3 times higher sensitivity than PPy/Pt modified electrode. Reduction behaviour of Cu(II), As(IlI), Pb(II), and Cd(II) couldn't be seen at PPy/GC electrode,Its metals had not lnterfered with Cr (VI) determination.

• Journal of Microbiology and Biotechnology
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• v.22 no.5
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• pp.690-698
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• 2012

Cr-B2, a Gram-negative hexavalent chromium [Cr(VI)] reducing bacteria, was isolated from the aerator water of an activated sludge process in the wastewater treatment facility of a dye and pigment based chemical industry. Cr-B2 exhibited a resistance for 1,100 mg/l Cr(VI) and, similarly, resistance against other heavy metal ions such as $Ni^{2+}$ (800 mg/l), $Cu^{2+}$ (600 mg/l), $Pb^{2+}$ (1,100 mg/l), $Cd^{2+}$ (350 mg/l), $ZN^{2+}$ (700 mg/l), and $Fe^{3+}$ (1,000 mg/l), and against selected antibiotics. Cr-B2 was observed to efficiently reduce 200 mg/l Cr(VI) completely in both nutrient and LB media, and could convert Cr(VI) to Cr(III) aerobically. Cr(VI) reduction kinetics followed allosteric enzyme kinetics. The $K_m$ values were found to be 43.11 mg/l for nutrient media and 38.05 mg/l for LB media. $V_{max}$ values of 13.17 mg/l/h and 12.53 mg/l/h were obtained for nutrient media and LB media, respectively, and the cooperativity coefficients (n) were found to be 8.47 and 3.49, respectively, indicating positive cooperativity in both cases. SEM analysis showed the formation of wrinkles and depressions in the cells when exposed to 800 mg/l Cr(VI) concentration. The organism was seen to exhibit pleomorphic behavior. Cr-B2 was identified on the basis of morphological, biochemical, and partial 16S rRNA gene sequencing chracterizations and found to be Acinetobacter sp.

• Textile Coloration and Finishing
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• v.17 no.1
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• pp.20-29
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• 2005

Cotton fabric was treated with a reactive anionic agent in order to have anionic sites(-S03-) on it, which made it possible for the fabric to adsorb various cationic materials. In this study, the adsorptivity of various heavy metal ions such as Pb(II), Cd(II), Cr(III), Co(II), Cu(II), Ni (II) and Cr(VI) on the cotton fabrics treated with anionic agent was examined at the various conditions; concentrations of heavy metal ions, pHs of solution, reaction time and temperature. As a result, the adsorptivity of the heavy metal ions on the cotton fabrics treated with the anionic agent was highly increased comparing to that of untreated cotton fabrics. The order of the adsorptivity was as follows: $Pb(II)>Cd(II)>Cu(II)\geqNi(II)\geqCo(II)>Cr(III)\ggCr(VI)$. The adsorption amounts of most heavy metal ions were increased in weak alkaline conditions and were reached to an adsorption equilibrium within 10 ~ 30 minutes. The maximum adsorption ratios of Pb(II) and Cd(II) were respectively 99% and 80% of the initial concentration of heavy metal ions. Therefore the anionized cotton fabrics seem to be utilized as an adsorption fabrics for the removal of heavy metal ions in the waste water.

• Analytical Science and Technology
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• v.19 no.4
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• pp.280-284
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• 2006

The objective of this study is to investigate the removal of heavy metal by using the coprecipitation of barium sulfate. Several parameters governing the efficiency of the coprecipitation method were evaluated by the pH of sample solution, amount of coprecipitant, and addition of sulfide for the removal of As(V), Cd(II), Cr(III), Cr(VI), Cu(II), Hg(II) and Pb(II) metal ions ($10{\mu}g/ml$ each). The coprecipitation was about 80% - 95% only for lead at low pH but under 10% for other ions. The amount of removal was about 95% - 100% for Cd, Hg, Pb, Cu in the all pH range by the addition of sulfide with barium sulfate but As(V) and Cr(III, VI) ions were not affected by the same conditions.