• Resources Recycling
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• v.7 no.3
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• pp.11-16
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• 1998

Simulated waste liquid containing 50 ppm cobalt ion was t$\xi$sted by precipitate flotation using a sodium lauryl sulfate as a c collector. The effects of initial cobalt ion concentration, pH, surfactant concentration, flotation time, gas flow rate and foreign i ions on removal efficiency of cobalt ion were studied. Pretreatment of the waste liquid with 35% $H_2O_2$, prior to precipitate f flotation made shin of optimal flotation pH from the strong alkalinity to weak alkaline range and made a favorable flotation of c cobalt ion in wide range of pH. For the result of this experiment, 99.8% removal efficiency was obtained on the conditions of initial coball ion concentration 50 ppm, pH 9.5 gas flow rate 70 mllmin, flotation time 30 min. The simulate ion was fanned t to be the most harmful ion against removal of cobalt by precipitate flotation of the species which were tested The presence of 0.1 M of $SO_4^{2-}$ ion decreased remo,때 $\xi$폐iciency of cobalt to 90% while the cobalt were almost entirely removed in the a absence of sulfate ion.

• Analytical Science and Technology
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• v.23 no.5
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• pp.429-436
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• 2010

The present research evaluates the efficiency of mixed resins between anion exchange resin and active carbon. We expected synergic effect from advantages of both adsorbents. Especially, this research focused on the removal of high cencentrated perchlorate ion from demilitarization solution. The total amount of the adsorbed perchlorate ion is increased considerably with mixed resins between mono functional anion exchange resin and granular active carbon from a single adsorbent. Results demonstated that this process not only improve the efficiency of adsorbing perchlorate, but save the time, space and cost for treating perchlotrate waste solution, because of reducing organic contaminant removing process. The interference effects from coexisting anions are not significant and can successfully applied to real demilitarization sample.

• Membrane Journal
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• v.8 no.3
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• pp.148-156
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• 1998

Diffusion dialysis is a membrane process driven by concentration difference using ion-exchange membranes and has been employed for many years for the acid recovery from acidic waste generated in steel, metal-refining and dectro-plating industries. Theoretically acid flux increases in propomon to the acid concentration difference. At acid concentrations higher than 3 N HCl, however, the acid flux had not increased linearly with the concentration difference. In this paper the effects of acid concentrations on diffusion dialysis for hydrochloric acid recovery and the acid transport mechanism in an anion exchange membrane were studied by membrane sorption tests and diffusion clialysis cell tests. The experimental results showed that the molecular diffusion was a major transport mechanism in a low acid concentration range and the proton leakage through an anion exchange membrane played an important role at higher acid concentrations. Also osmotic water transport and membrane dehydration retarded the transport of protons and caused the permeate flux to decrease.

• Korean Journal of Food Science and Technology
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• v.33 no.1
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• pp.7-11
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• 2001

The influence of temperature and calcium concentration on the gelation kinetics of purified Aigeok system has been investigated by small deformation oscillatory measurement. DE(degree of esterification) of the present sample was indicated of low methoxyl Aigeok polysaccharide by FT-IR. The calcium induced gelation of Aigeok has been studied. Both moduli reached the saturation value during the period of experiments. Rate constant increased with increasing calcium concentration, however above 4.08 mM calcium chloride caused a sudden drop in gel strength. The experimental result that the decrease in gel strength at high calcium concentration was seems to be phase separation or competitive inhibition between calcium ions. The storage and loss shear moduli decreased with increasing temperature. The rate constant of Aigeok system remarkably dropped above $35^{\circ}C$. Thus hydrogen bonding is prior to hydrophobic interaction for Aigeok molecule.

• Journal of the Korean Chemical Society
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• v.46 no.5
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• pp.412-429
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• 2002

Chiral separation of gemifloxacin, an quinolone antibacterial agent, using (+)-(18-crown-6)-tetracar-boxylic acid $(18C6H_4)$ as a chiral selector was performed by capillary electrophoresis (CE). Direct analysis of quinolone antibacterial agent in body fluid is beneficial in terms of fast analysis time, multicomponent analysis. However, high con-centration of sodium ion in body fluid can prevent gemifloxacin from interacting with $18C6H_4$ since sodium ion has high affinity with $18C6H_4$ due to the strong charge interaction. Ethylenediaminetetraacetic acid (EDTA), as a chelating ligand, was added in the running buffer in order to reduce the interaction between sodium ion and the chiral selector. Increased separation efficiency and reduced migration time were observed while sodium ion exists in the sample solution at the concentration up to 150 mM.

• Journal of the Mineralogical Society of Korea
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• v.22 no.3
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• pp.249-259
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• 2009

The objective of this research was to find out the physical properties, such as dispersion and coagulation, of soil minerals depending on the types and concentrations of the cations in aqueous solution. Hwangto samples were obtained from 90 to 130 cm from surface at Jangdong-ri, Donggang-Myon, Naju, Chonnam Province. The clay fraction (< $2\;{\mu}m$) was separated by sedimentation method from the bulk soils. Both Hwangto and clay fractions, and the same samples after removal of amorphous and crystalline iron oxides were used in this experiment. The effect of 4 cations ($Na^+$, $K^+$, $Mg^{2+}$, $Ca^{2+}$) and their concentrations on settling speed and basal spacing of the minerals were observed to examine the physical properties of the soil and clay minerals. Hwangto mainly consisted of quartz, and the clay fractions consisted of kaolinite, illite, and vermiculite. The bulk soils contained 16.3 mg/kg of amorphous iron oxides and 436 mg/kg of crystalline iron oxides. Clay fractions were dispersed better than bulk soils due to their smaller particle size than that of the bulk samples in the aqueous solution. The bulk and clay samples were dispersed better when iron oxides were removed because of coating of minerals by the iron oxides. Clay minerals were settled faster as the charge and the concentration of cations added increased. The d-spacing of kaolinite and illite did not change when 4 types of cations were added. The d-spacing of vermiculite showed $14.04\;{\AA}$ when divalent cations were added while that of vermiculite showed $13.9\;{\AA}$ when monovalent cations were added. It may be attributed to the hydration radii of cations. This study indicated that both coating of iron oxides on minerals and types and concentrations of cations affect dispersion of minerals in solution and d-spacing of expanding clay minerals such as vermiculite.

• Analytical Science and Technology
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• v.10 no.3
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• pp.161-167
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• 1997

This is on hydrogen ion-selective memebrane electrodes which were made of tetrabenzylmethylenediamine (TBMDA), tetrabenzylethylenediamine (TBEDA), tetrabenzylpropylenediamine(TBPDA) and tetrabenzylhexylenediamine(TBHDA) as neutral carriers. Their response potentials to carbon number between amino groups showed linear selectivities to hydrogen ion in the range of pH 1~pH 9, pH 2~pH 9, pH 3~pH 9 and pH 4~pH 9 and slopes were 48mV/pH, 52mV/pH, 64mV/pH, 59mV/pH respectively. The interferences effect on the cations were measured to alkali metal ions($Li^+$, $Na^+$, $K^+$), alkaline earth metal ions ($Mg^{2+}$, $Ca^{2+}$, $Sr^{2+}$, $Ba^{2+}$), transition metals ions($Cu^{2+}$, $Ni^{2+}$, $Co^{2+}$) and anions($I^-$, $Br^-$, ${NO_3}^-$, $SCN^-$), and selectivity coefficients were measured by separate-solution method. The membrane electrode made of TBMDA among the electrodes showed the best selectivity in acidic solution.

• Journal of the Korean Electrochemical Society
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• v.19 no.3
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• pp.95-100
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• 2016

A method for electrochemical degradation of the perchlorate anion ($ClO_4{^-}$) using mercury film electrode has been studied. Electrochemical method has relatively simple pre-treatment. However, electrochemical method should avoid interference from hydrogen evolution at the applied potential to degradation of perchlorate ion, and thus applied electrode should have large hydrogen overvoltage which suppressed the hydrogen evolution at the working reduction potential to prevent hydrogen evolution. In this study, we used mercury film electrode as a working electrode which has a large overvoltage. Ag / AgCl (sat. NaCl) was used as a reference electrode, and platinum was used as a counter electrode. Mercury film electrode was made by cyclic voltammetry (CV) method. The deposition time was decided as 10 minute, and the stability of the mercury electrode in perchlorate solution was confirmed by CV. The reduction potential of perchlorate was checked by using CV method, and decomposition of perchlorate was performed by using chronoamperometric (CA) method. Also, ion chromatography (IC) was used to confirm the degradation rates of perchlorate.

• Analytical Science and Technology
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• v.10 no.6
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• pp.427-432
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• 1997

A selective method for the determination of iron(III) ion with a sodium dodecyl sulfate(SDS) modified glassy carbon electrode was proposed. It was based on the electrostatic attraction and complexation of the SDS modifier, $(DS^-)_n-Fe^{3+}$. The determination of iron(III) ion was performed by a differential pulse voltammetry(DPV), and the reduction peak potential of $(DS^-)_n-Fe^{3+}$ was +0.466(${\pm}0.002$)V vs. Ag/AgCl. For the determination of iron(III) ion, a linear calibration curve was obtained within the iron(III) ion concentration range of $0.50{\times}10^{-5}{\sim}10{\times}10^{-5}mol/L$, and the detection limit was $0.14{\times}10^{-5}mol/L$. $Cu^{2+}$, $Ni^{2+}$, $Co^{2+}$, $Pb^{2+}$, $Zn^{2+}$, and $Mn^{2+}$ showed little or no effect on the determination of iron(III) ion, respectively. But, ion such as each $CN^- $ and $SCN^-$ interfered seriously.

• Membrane Journal
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• v.9 no.4
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• pp.230-239
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• 1999

Perchlorate ion-selective electrodes in PVC membranes that respond linearly to concentration 106 M were developed by incorporating the quaternary phosphonium salts as a canier. The effects of the chemical structure, the contents of canier, the kind of plasticizer and the membrane thickness on electrode characteristics such as the electrode slope, the linear respone range and the detection limit were studied. With this results, the detectable pH range, selectivity coefficients and AC impedance characteristics were compared and investigated. The perchlorate ion substituents of the quaternary phosphonium salts like tetraoctylphosphonium perchlorate (TOPP) , tetraphenylphosphonium perchlorate(TPPP), and tetrabutylphosphonium perchlorate(TBPP) as a canier were used. The electrode characteristics were better in the ascending order of TBPP < TPPP < TOPP, with the increase of carbon chain length of the alkyl group. Dioctylsebacate(OOS) was best as a plasticizer, the canier contents were better with 11.76 wt% and the optimum membrane thickness was 0.19 mm. Under the above condition, the electrode slope was 56.58 mV/$^P{ClO}_4$,the linear response range was $10^{-1}$\times$10^{-6}$ M, the detection limit was 9.66 x $10^{-7}$ M. The performance of electrode was better than Orion electrode. The electrode potential was stable within the pH range from 3 to 11. The order of the selectivity coefficients for the perchlorate ion was sol < F < Br < 1. With the result of impedance spectrum, it was found that the equivalent circuit for the electrode could be expressed by a series combination of solution resistance, parallel circuit consisting of the double layer capacitance and bulk resistance and Warburg impedance. And solution resistance was almost not appeared and Warburg impedance was highly appeared by diffusion. Then Warburg coefficient was 1.32$\times$$10^74 $\Omega$ $\cdot$ ${cm}^2/s^{1/2}$.