• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.355-360
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• 1999

Polymer cement is made by the modifying ordinary cement concrete with polymer additive. Until now polymer cement concrete is not used for the structural member, but it is growing to be considered as developing uses such as a waterproof of roof slab, the structural member for protecting corrosion, and a road pavement. The plymer cement concrete, being used for those uses, is superior to the cement concrete against the inorganic, organic acid, salt of acetic acid and organic solvents generally. In this paper, the polymer cement concrete was made by the ratio of 1:1 of sands and tailing in fine aggregate in order to solve the environmental pollution which causes the social problem by the tailing, It was measured for the compressive strength, flexural strength, and chemicals resistance was tested by dealing with 10% HCI, 20% NaOH and 10% NaCl aqueous solution.

• Journal of the Korean institute of surface engineering
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• v.47 no.5
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• pp.269-274
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• 2014

Electroless plating process as a solution deposition method is a viable means of preparing conductive metal films on non-conducting substrates through chemical reactions. In the present study, the preparation and properties of electroless Ni-plating on flexible silicone rubber are described. The process has been performed using a conventional Ni(P) chemical bath. Additives and complexing agents such as ammonium chloride and glycine were added and the reaction pH was controlled by NaOH aqueous solution. Ni deposition rate and crystallinity have been found to vary with pH and temperature of the plating bath. It was shown that Ni-films having the high crystallinity, enhanced adhesion and optimum electric conductivity were formed uniformly on silicone rubber substrates under pH 7 at $70^{\circ}C$. The conductive Ni-plated silicone rubber showed a high electromagnetic interference shielding effect in the 400 MHz-1 GHz range.

• Resources Recycling
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• v.31 no.5
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• pp.3-19
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• 2022

Electro-membrane technology is a process for separating and purifying substances in aqueous solution by electric energy using an ion exchange membrane with selective permeability, such as electrodialysis (ED) and bipolar electrodialysis (BMED). Electro-membrane technology is attracting attention as an environmental friendly technology because it does not generate by-products during the process and the recovered base or acid can be reused during the process. In this paper, we investigate the principles of ED and BMED technologies and various characteristics and problems according to the cell configuration. In particular, by investigating and analyzing research cases related to the treatment of waste sodium sulfate (Na₂SO₄), which is generated in large amounts during the metal recovery process.

• Journal of the Korean Chemical Society
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• v.9 no.4
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• pp.179-184
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• 1965

Korean acid clays and Japanese acid clay were 1 N KCl solution and then their acidities were determined by measuring pH of the filtrates produced. And on examining the effect of neutral salt solution, such as KCl, NaCl, $BaCl_2,\;Pb(NO_3)_2\;and\;CuSO_4$, on the acidity, it was found that the effect decreased in order mentioned above and this situation proved to be in accord with Lyotrope series, i.e., the order of $K^+>Na^+>Ba^{++}>Pb^{++}>Cu^{++}.$ And after adsorbing cation, $Al_2O_3\;and\;Fe_2O_3$ which dissolved out of acid clay were measured, with the result that the amounts dissolved out were nearly proportional to acidity. This result accords with Kobayashi and Yamamoto's theory that the cause for acidity of clays is due to the fact that HCl which is formed initially by exchange of cation reacts with solid clay, and then chlorides dissolved out bring about hydrolysis, then resulting in the second formation of HCl. On measuring the rate which acid clay adsorbed dye in aqueous solution of basic and acid dyes, it was found that acid dye had no relation to acidity, and though it was not adsorbed by acid clay, the adsorption rate of basic dye was proportional to acidity. After adsorbing basic dye, pH was proportional to both acidity of solid acid and its adsorption rate of dye. Hence, it was concluded that the adsorption of basic dye was in accord with adsorption mechanism of neutral salt. This study led to find the acidic cause of solid acid and its adsorption mechanism of dye in aqueous solution.

• Bulletin of the Korean Chemical Society
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• v.29 no.5
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• pp.969-973
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• 2008

Solvent extraction using a Schiff-base, salen$(NEt_2)_2$, as a chelating agent has been conducted on several water samples to study the determination of trace Cu(II), Mn(II) and Zn(II). Experimental conditions for the formation and extraction of metal complexes were optimized with an aqueous solution similar in composition to the samples. The matrix difference between the sample and standard solutions was approximately matched, and the pH of each sample solution was adjusted to 9.5 with $NaHCO_3/NaOH$ buffer. The concentration of salen$(NEt_2)_2$ was $7.3\;{\times}\;10^{-3}$ mol/L, and the complexes were extracted into MIBK solvent followed by the measurement of AAS absorbance. The potential interference of concomitant ions was investigated, but no interference from alkaline and alkali earth ions was shown in this procedure. The given procedure is precise, as judged from the relative standard deviation of less than 5% for five measured data. The recovery of 93-103% shows that this method is quantitative for such trace metal analysis.

• The Journal of Natural Sciences
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• v.8 no.2
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• pp.119-127
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• 1996

The effect of sodium hydroxide treatment on some physicochemical properties of zeolite mordenite mineral was studied with chemical analyses, powder X-ray diffraction, thermal analyses, infrared analysis, measurement of carbon dioxide adsorption and gas chromatography. Mordenite mineral from tuffaceous rocks in Yeongil and Wolsung area was used as a starting material and treated with 0.1-5N NaOH aqueous solution at about $95^{\circ}C$ in the water bath for three hours.At the concentration of sodium hydroxide below 0.5N, all chemical compositions in the tuff were virtually insoluble and the mordenite structure did not change. At the concentration above 1N, the chemical compositions such as silica, alumina, etc., were dissolved. The dissolution ratio of silica was lager than that of alumina, and the ratio of silica to alumina in the tuff decreased sharply in the concentration range of 2 to 3N. Intensity of X-ray diffraction peak of mordenite (202) plane and the adsorbed amount of carbon dioxide also decreased with the increasing concentration of sodium hydroxide above 1N. These decreases corresponded to the degree of mordenite structure collapsed.The separation of gas chromatography of nitrogen, oxygen and carbon monoxide was not affected by the sodium hydroxide treatment, but elution peaks of methane and krypton tended to be broadened and their retention time was shortened. The elution peaks of both methane and krypton tended to be overlapped with those of nitrogen and oxygen.

• Membrane Journal
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• v.28 no.3
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• pp.180-186
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• 2018

The nano-composite membranes were prepared onto the polyvinylidene fluoride (PVDF) hollow fiber membranes through twice dip-coating known layer-by-layer method. For the first coating, poly(vinylsulfonic acid, sodium salt)(PVSA) and Poly(styrene sulfonic acid)(PSSA) were used with varying the concentration and ionic strength (IS) and the poly(ethyleneimine)(PEI) as the second coating material was fixed at 10,000 ppm and IS = 0.3. To characterize the prepared nano-composite membranes, the permeabilities and rejection ratio were measured for each 100 ppm NaCl, $CaSO_4$, $MgCl_2$, and 25 ppm MO aqueous solution. The rejections were increased as the concentrations of coating materials increased. And it was confirmed that the salt rejections for PSSA as the coating material were higher than for PVSA. Typically, the permeability, 1.848 LMH and the rejection for MO 76.3% were obtained at the coating conditions of PSSA 30,000 ppm and I.S = 1.0.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.406-409
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• 1999

Experimental Investigations were carried out to remove NOx, SOx simultaneously from simulated flue gas[NO(0.02%)-SO$_2$(0.08%)-$CO_2$-Air-$N_2$] by using a plasma chemical reaction. Ammonia gas(14.81%) balanced by argon was diluted by all and was Introduced to mall simulated flue gas duct through NH$_3$ Injection system which is in downstream of reactor. The NH$_3$ molecular ratio(MR) was determined based on (NH3) to [NO+S0$_2$]. MR is 1, 1.5, 2.5. The NOx removal rate significantly increased with increasing NaOH bubble quantity. The SO$_2$ removal rate was not significantly effected by applied voltage, however it fairly Increased with increasing NH$_3$ molecule ratio. By-product aerosol particle was observed by XRD(X-ray diffraction) after sampling, The NOx, SOx removal rates, when H2O vapour bubbled by dry all was injected to plasma reactor, were better than those of other cases. When aqueous NaOH solution(20%) bubbled by 2.5( ι /min) of $N_2$ and 0.5 ( ι /min) NH$_3$(MR=1.5) were injected to simulated flue gas, The NOx. SOx removal rate was 95 ~ 100[%]

• Macromolecular Research
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• v.16 no.2
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• pp.178-181
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• 2008

Polystyrene (PS) nanospheres with a monodisperse size distribution, positive surface charge and high molecular weight were successfully synthesized using various types of metal stearates in an aqueous NaOH medium. The diameter of the PS nanospheres was controlled from 80 to 450 nm by changing the type of metal stearate. It was also found that controlling the NaOH concentration in solution was important for producing monodisperse PS nanoparticles. The nanospheres prepared with zinc stearate possessed a positive surface charge of 60 to 80 mV, confirming that PS particles were functionalized with metal stearates. It is believed that the metal stearates provide PS particles with not only colloidal stability but also a positive surface charge.

• Resources Recycling
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• v.32 no.1
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• pp.21-32
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• 2023

Because the application of lithium has gradually increased for the production of lithium ion batteries (LIBs), more research studies about recycling using solvent extraction (SX) should focus on Li⁺ recovery from the waste solution obtained after the removal of the valuable metals nickel, cobalt and manganese (NCM). The raffinate obtained after the removal of NCM metal contains lithium ions and other impurities such as Na ions. In this study, we optimized a selective SX system using di-(2-ethylhexyl) phosphoric acid (D2EHPA) as the extractant and tri-n-butyl phosphate (TBP) as a modifier in kerosene for the recovery of lithium from a waste solution containing lithium and a high concentration of sodium (Li⁺ = 0.5 ~ 1 wt%, Na⁺ = 3 ~6.5 wt%). The extraction of lithium was tested in different solvent compositions and the most effective extraction occurred in the solution composed of 20% D2EHPA + 20% TBP + and 60% kerosene. In this SX system with added NaOH for saponification, more than 95% lithium was selectively extracted in four extraction steps using an organic to aqueous ratio of 5:1 and an equilibrium pH of 4 ~ 4.5. Additionally, most of the Na⁺ (92% by weight) remained in the raffinate. The extracted lithium is stripped using 8 wt% HCl to yield pure lithium chloride with negligible Na content. The lithium chloride is subsequently treated with high purity ammonium bicarbonate to afford lithium carbonate powder. Finally the lithium carbonate is washed with an adequate amount of water to remove trace amounts of sodium resulting in highly pure lithium carbonate powder (purity > 99.2%).