• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.361-369
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• 2018

A manufacturing method has been devised to prepare novel heterogeneous cation exchange membranes by mixing ethylene vinyl acetate (EVA) copolymers with a commercial cation exchange resin. Optimum material characteristics, mixture ratios and manufacturing conditions have been worked out for achieving favorable membrane performance. Ion exchange capacity, electrical resistance, water uptake, swelling ratio and tensile strength properties were measured. SEM analysis was used to monitor morphology. Effects of vinyl acetate (VA) content, melt index (MI) and ion exchange resin content on properties of heterogeneous cation exchange membranes have been discussed. An application test was carried out by mounting a selected membrane in a membrane capacitive deionization (MCDI) system to investigate its desalination capability. 0.92 meq/g of ion exchange capacity, $8.7{\Omega}.cm^2$ of electrical resistance, $40kgf/cm^2$ of tensile strength, 19% of swelling ratio, 42% of water uptake, and 56.4% salt removal rate were achieved at best. VA content plays a leading role on the extent of physical properties and performance; however, MI is important for having uniform distribution of resin grains and achieving better ionic conductivity. Overall, manufacturing cost has been suppressed to 5-10% of that of homogeneous ion exchange membranes.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.38-43
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• 2002

A series of tests were performed to investigate the effects of pH and contamination level on cation exchange capacity and zeta potential in kaolinite loaded with lead. Test results show that cation exchange capacity of kaolinite is found to be in the range from 4 to 20meq/100g and it increased with increasing pH up to the converged number about 20meq/100g over pH 8. And then CEC has a tendency to reduce and converge to zero with increasing the concentration of Pb in the kaolinite surface. Moreover, zeta potential of kaolinite contaminated with lead is found to be in the range from -10 to 5mV, and zero point of charge is measured at about pH 3.5. Zeta potential of kaolinite contaminated with lead decreases with increasing pH values and decreasing Pb concentration of kaolinite.

• Proceedings of the Membrane Society of Korea Conference
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• 1999.10b
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• pp.52-54
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• 1999

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.11a
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• pp.351-352
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• 2018

• Applied Chemistry for Engineering
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• v.8 no.1
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• pp.67-75
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• 1997

Heterogeneous cation exchange membrane consisting of cation exchange resin particles (diameter of less than $149{\mu}$) which are finely dispersed in a polyethylene matrix, were produced as forms of sheet. The characteristics were measured after treating hot water or saturated sodium chloride. When membranes were treated with hot water or saturated sodium chloride, cation exchange resin particles swell and expand pushing away the polyethylene matrix of membranes. The above treatment results the formation of narrow cavities between a cation exchange resin particles and polyethylene matrix, and the formation of fine micro-cracks on the polyethylene matrix. Thus, we were obtained good physical and electrochemical properties. On the treatment with hot water or saturated sodium chloride, the optimum conditions for good heterogeneous cation exchange membrane were treatment time of 30min and treatment temperature of $90^{\circ}C$.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.1
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• pp.65-75
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• 2015

In this study, cation and anion exchange process for performance evaluation was conducted. A pilot plant for the ultrpure water production was installed with the capacity of $25m^3/d$. The various production rate and regeneration of ion exchange rate were tested to investigate the design parameters. The test resulst was applied to calculate the operating costs. Changing the flow rate of the ion exchange capacity of the reproduction reviewed the cation exchange process as opposed to the design value is 120 to 164% efficiency, whereas both anion exchange process is 82 to 124% efficiency, respectively. This results can be applied for more large scale plant if the scale up parameters are consdiered. The ion exchange capacity of the application in accordance with the design value characteristic upon application equipment is expected to be needed. In this study, the performance of cation and anion exchange resin process was evaluated with pilot plant($25m^3/d$). The ion exchange capacity along with space velocity and regeneration volume was evaluated. In results, the operation results was compared with design parameters.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.1-4
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• 2003

LDPE/polystyrene cation exchange membranes were prepared through a monomer-sorption method and UV radiation polymerization. The reaction behaviors in the preparation were investigated. The membranes prepared were characterized in terms of physical and electrochemical properties. The membranes exhibited reasonable properties for an ion-exchange membrane with weight gain (Wr) of above 0.3, electrical resistance of below 1.0 Ω $\textrm{cm}^2$ and ion-exchange capacity of 1.8 meq/g-dry membrane. DSC studies and FE-SEM image revealed the formation of a homogeneous membrane. Both the current-voltage and the chronopotentiometric curves of the membranes indicated that LDPE/polystyrene membranes can be properly used at a high current density, and the surface homogeneity of cation-exchange sites in the membrane was comparable to that in a commercial membrane.

• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.909-913
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• 2018

A hydrocarbon trap (HT) plays an important role of controlling vehicle emissions in the so-called cold emission period by holding hydrocarbons until three way catalysts (TWCs) are thermally activated. In this study, we have investigated the adsorption characteristics of cation (H, La, K, and Ag)-exchanged ZSM-5 zeolites for hydrocarbons (propylene, n-butane, and toluene) by DFT (density functional theory)-based computational chemistry. Cation exchange is to improve the hydrothermal stability of zeolites and their adsorption capacity, thereby rendering cation-exchanged zeolites promising materials for HT. The idea of cluster approximation makes the calculation of adsorption energies superbly efficient in computation. The results showed that Ag-exchanged ZSM-5 would be the best for the adsorption of all three adsorbates, without often encountered Ag oxidation in experiments. Besides, the hydrothermal stability of La-exchanged ZSM-5 was confirmed from the change of geometrical parameters by cation exchange, and it showed good adsorption capacity for propylene and toluene. Hydrogen-exchanged ZSM-5 was also good for hydrogen adsorption, but had poor hydrothermal stability.

• Journal of the Korean Chemical Society
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• v.4 no.1
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• pp.62-66
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• 1957

With the intention of preparing cation exchangers from the domestic coals, and using these for softening hard water and some other purposes, seven kinds of raw coal were tested and the results are as follows. 1) The following conditions of preparation were given the good results. Reaction time 5 hours Reaction temperature $95^{\circ}$ Concentration of sulfuric acid 98% Amount of sulfuric acid 10 times to the sample (as weight) 2) The raw coals which is rich in fixed carbon and have the fuel ratio 0.8 to 1.0 were suitable, and Kampo lignite has shown the best results. 3) The cation exchangers from coals were able to exchange the cation, both hydrogen and sodium type dynamically and statically, like the synthetic ion exchange resin. The exchange capacities were as follows. Total capacity 1.60 meq/g. Breakthrough capacity 1.30 meq/g. Usable breakthrough capacity 1.20 meq/g National Central Research laboratory

• Membrane Journal
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• v.10 no.2
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• pp.66-74
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• 2000

In consideration that a high tensile strength and ion exchange capacity are maintained as the swelling of membrane is controlled by the coagulation of PSf with the introduction of ion exchange groups and PPSS without the introduction of ion exchange groups, the block copolymer of PSf and PPSS were synthesized. The cation exchange membrane was prepared by sulfonation with CSA and casted. The synthesized block copolymer and cation exchange membrane were characterized by FT-IR and their thermal stability was confirmed by TGA. The optimum sulfonation could be accomplished at a mole ratio of BPSf to CSA 1:3. The best electrochemical properties obtained by the optimal condition were area resistance of 4.37 $\Omega$ㆍ$\textrm{cm}^2$, ion exchange capacity of 1.71 meq/g dry membrane, water content of 0.2941 g $H_2O$/g dry membrane, and fixed ion concentration of 5.81 meq/g $H_2O$. When GBL was used as an additive, area resistance was increased by 13.7 % and ion exchange capacity was increased by 14.6%. When the membrane was fabricated in a form of composite using non woven cloth as a support. the tensile strength of membrane could be improved, but the electrochemical characteristics were not influenced.