• Journal of Korean Society on Water Environment
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• v.33 no.2
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• pp.211-218
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• 2017

This experiment was carried out with the purpose of testing cadmium adsorption abilities of multi wall carbon nanotube (MWCNT), activated carbon, and synthesized layered double hydroxide (LDH). In the acidic condition, only MWCNT was effective for removing cadmium ion in the aqueous phase while other adsorbents rarely removed it. The MWCNT and cadmium ion adsorption reactions followed pseudo-first order kinetic. When the initial pH value was neutral (pH = 7), cadmium ion was rapidly removed by MWCNT and activated carbon in 4 hr (100% and 99.2%, respectively). Increasing adsorbent dosages affects the pH evolution and cadmium ion removal (0 to 99%). Cytotoxicity test showed that both MWCNT and LDH has low cytotoxic effects on three kind of human cells (A549, HS-294t, and HT-29).

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.2925-2930
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• 2013

We present results of molecular dynamics simulations for hydroxide ion in supercritical water of densities 0.22, 0.31, 0.40, 0.48, 0.61, and 0.74 g/cc using the SPC/E water potential with Ewald summation. The limiting molar conductance of $OH^-$ ion at 673 K monotonically increases with decreasing water density. It is also found that the hydration number of water molecules in the first hydration shells around the $OH^-$ ion decreases and the potential energy per hydrated water molecule also decreases in the whole water density region with decreasing water density. Unlike the case in our previous works on LiCl, NaCl, NaBr, and CsBr [Lee at al., Chem. Phys. Lett. 1998, 293, 289-294 and J. Chem. Phys. 2000, 112, 864-869], the number of hydrated water molecules around ions and the potential energy per hydrated water molecule give the same effect to cause a monotonically increasing of the diffusion coefficient with decreasing water density in the whole water density region. The decreasing residence times are consistent with the decreasing potential energy per hydrated water molecule.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.5
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• pp.458-465
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• 2018

This study reports the fabrication of anion exchange membranes (AEMs) containing two kinds of functional groups: i) trimethylphosphite (TMP) and ii) trimethylamine (TMA). We carried out the synthesis of polymers to enhance thermal stability and ion conductivity. The alternative polymer was prepared using 2,2-bis(4-hydroxy-3-methylphenyl)propane and decafluorobiphenyl. The membrane was fabricated by solution casting method. The thermal stability of membranes was examined by TGA. The physiochemical properties of membranes were also investigated in terms of water uptake, swelling ratio, ion exchange capacity, and ion conductivity. The hydroxide ion conductivity of the membranes reached about 20.2 mS/cm for quaternary ammonium poly(arylene ether) (QA-PAE) containing TMA moiety and 5.1 mS/cm for quaternary phosphonium PAE (QP-PAE) containing TMP moiety at $90^{\circ}C$.

• Journal of the Korea Institute of Building Construction
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• v.19 no.1
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• pp.31-38
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• 2019

In this study, amine derivatives and ion exchange resins were selected to actively control penetration ions ($SO{_4}^{2-}$, $Cl^-$) as the element technology of repair materials for concrete structures in drainage environments. Ions ($SO{_4}^{2-}$, $Cl^-$) adsorption performance and corrosion resistance of calcium hydroxide solution with amine derivative and ion exchange resin were confirmed by ion chromatography and potentiostat analysis. As a result of the experiment, it was confirmed that the amine derivative is excellent in the adsorption of chlorine ion and the ion exchange resin is excellent in the adsorption of sulfate ion. It has been confirmed that corrosion resistance can be increased by proper combination of two materials in the calcium hydroxide solution containing sulfate ion and chloride ion simulating sewage environment.

• Journal of the Korean institute of surface engineering
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• v.47 no.4
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• pp.147-154
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• 2014

Formation behavior of PEO (Plasma Electrolytic Oxidation) films on AZ31 Mg alloy was studied in aqueous solutions containing various concentrations of hydroxide ion ($OH^-$) and silicate ion ($SiO_3{^{2-}}$) by voltage-time curves, and corrosion resistance of the PEO film-covered specimen was investigated by immersion test in 0.5 M NaCl solution. From the analyses of the voltage-time curves, it is suggested that two different types of anions are essentially needed for the formation of PEO films on AZ31 Mg alloy: film formation agent and local film breakdown agent. $SiO_3{^{2-}}$ ion acts only as a film formation agent but $OH^-$ ion acts not only as a film formation agent but also film breakdown agent. The PEO films prepared on AZ31 Mg alloy in alkaline silicate solution showed very good corrosion resistance without any pitting or filiform corrosions up to 480 h of immersion in 0.5 M NaCl.

• Journal of the Korean Chemical Society
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• v.16 no.4
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• pp.249-256
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• 1972

Hadong-Kaolin was treated with aqueous sodium hydroxide solution. The crystalline structure was studied by X-ray powder diffraction method. The optimum conditions for various crystal formation were as follows: Crystal Concentration Temp. reating time Halloysite 1~4 N NaOH $60^{\circ}C$ 0.5${\sim}$4 hr Sodium A zeolite 0.5${\sim}$2 N NaOH 80${\sim}$$100^{\circ}C$ 6${\sim}$20 hr Hydoxysodalite > 4 N NaOH 80${\sim}$$100^{\circ}C$ > 4 hr The ratio of $Na_2O to SiO_2$ for crystallizing sodium A zeolite was 0.5-1.5. The $Ca^{++}$ ion exchange capacity of produced sodium A zeolite for 0.2 N $CaCl_2$ solution at $25^{\circ}C$ was amounted to 65% of theoretical value.

• Journal of Korean Society on Water Environment
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• v.27 no.4
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• pp.486-490
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• 2011

As(V) adsorption on aluminum oxide powder which was recycled from industrial wastes containing aluminum hydroxide was evaluated. Aluminum oxide powder in this study was prepared by calcinating aluminum hydroxide wastes at$550^{\circ}C$. Spectroscopic analysis indicated that the aluminum hydroxide wastes were changed to aluminum oxide by calcination. Arsenic adsorption isotherm was conducted with variation of ionic strength and multiple-ion systems using Ca(II) and Cu(II). As(V) removal showed typical anionic adsorption characteristics that the removal efficiency decreased with increasing pH in single As(V) system as well as in binary and ternary system. More than 80% of As(V) at an initial concentration of $5{\times}10^{-5}$ M was removed from aluminum oxide powder in As(V) single system. The effect of ionic strength on As(V) adsorption was negligible, which indicated the strong bonding between aluminum oxide powder and As(V). The removal efficiency of As(V) was higher in a binary system with Cu(II) than in a binary system with Ca(II).

• Journal of the Korean Chemical Society
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• v.3 no.1
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• pp.18-22
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• 1954

The cation exchange resins are synthesized from p-phenolsulfonic acid, formalin, and sodium hydroxide catalyser, and the ion exchange properties of them are studied with respect to their reactant ratios. Maximum exchange capacity was 2.06 me/G, much smaller than the theoretical value of 3.42 me/G to be expected for that of the structure: Under the present experimental conditions, much -SO3H radical should have been split away.

• Proceedings of the KACD Conference
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• 2001.11a
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• pp.567.2-567
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• 2001

The purpose of this study was to evaluate the shape, the composition of Calcium Hydroxide Points (CH Point) and to determine the pH level in water. The shape of CH Point was measured by using a profile projector. The composition of the CH Point was analyzed by the X-ray diffraction and the EPMA. ＃60 CH Point was stored in 10ml of demineralized water that was replaced every day or not replaced for 7 days period. The pH levels of the water were measured by using an ion electrode with an ion meter every day.(omitted)

• Journal of the Korean Chemical Society
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• v.19 no.2
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• pp.123-129
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• 1975

The rate constants of the hydrolysis of phenylvinylsulfone were determined by ultraviolet spectrophotometry at various pH and a rate equation which can be applied over wide pH range was obtained. The reaction mechanism of hydrolysis of phenylvinylsulfone and especially the catalytic contribution of hydroxide ion which did not study carefully before in acidic media, can be fully explained by the rate equation obtained. The rate equation reveals that: below pH 7, the reaction is initiated by the addition of water molecule to phenylvinylsulfone. At above pH 9, the overall rate constant is only dependent upon the concentration of hydroxide ion.