• Membrane Journal
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• v.25 no.6
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• pp.515-523
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• 2015

While commercial polystyrene-based ion exchange membranes have simple manufacturing processes, they also possess poor durability due to their brittleness. Poly(ethylene glycol)methyl ether methacrylate with hydrophilic side chains of poly(ethylene glycol) was used as a co-monomer to make the membranes have improved flexibility. Hydrophilicity/hydrophobicity of the anion exchange membranes were able to be adjusted by varying the chain lengths of the poly(ethylene glycol). For the preparation of the anion exchange membranes, a porous PE substrate was immersed into monomer solutions and thermally polymerized. The prepared membranes were subsequently reacted with trimethylamine to produce anion exchange functional groups, Quaternary ammonium salts. The prepared pore-filled anion exchange membranes were evaluated in terms of ion exchange capacity, electric resistance, elongation at break and water uptake.

• Geomechanics and Engineering
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• v.7 no.2
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• pp.183-200
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• 2014

The expansivity of clayey soils is a complicated phenomenon which may affect the stability of geotechnical structures and geo-environmental projects. In all common factors for the monitoring of soil expansion, less attention is given to anion type of pore space solutions. Therefore, this paper is concerned with the impact of various concentrations of different inorganic salts including NaCl, $Na_2SO_4$, and $Na_2CO_3$ on the macro and microstructure behavior of the expandable smectite clay. Comparison of the responses of the smectite/NaCl and smectite/$Na_2SO_4$ mixtures indicates that the effect of anion valance on the soil engineering properties is not very pronounced, regardless of the electrolyte concentration. However, at presence of carbonate as potential determining ions (PDIs) the swelling power increases up to 1.5 times compared to sulfate or chloride ions. The samples with $Na_2CO_3$ are also more deformable and show lower osmotic compressibility than the other mixtures. This demonstrates that the barrier performance of smectite greatly decreases in case of anions with the non-specific adsorption (e.g., $Cl^-$ and $SO{_4}^{2-}$) as the salinity of solution increases. Based on the results of the X-ray diffraction and sedimentation tests, the high soil volumetric changes upon exposure to carbonate is attributed to an increase in the repulsive forces between smectite basic unit layers due to the PDI effect of $CO{_3}^{2-}$ and increasing the pH level which enhance the buffering capacity of smectite. The study concluded that the nature of anion through its influence on the re-arrangement of soil microstructure and osmotic phenomena governs the hydro-mechanical parameters of expansive clays. It seems not coinciding with the double layer theory of the Gouy-Chapman double layer model.

• Journal of Soil and Groundwater Environment
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• v.13 no.3
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• pp.21-26
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• 2008

Nitrate adsorption from aqueous solutions onto zinc chloride ($ZnCl_2$) treated coconut Granular Activated Carbon (GAC) was studied in a batch mode at two different initial nitrate concentrations (25 and 50 mg/L). The rate of nitrate uptake on prepared media was fast in the beginning, and 50% of adsorption was occurred within 10 min. The adsorption equilibrium was achieved within one hour. The mechanism of adsorption of nitrate on $ZnCl_2$ treated coconut GAC was investigated using four simplified kinetic models : the rate parameters were calculated for each model. The kinetic analysis indicated that pseudo-second-order kinetic with pore-diffusion-controlled was the best correlation of the experimental kinetic data in the present adsorption study.

• Journal of Korean Society of Water and Wastewater
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• v.34 no.6
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• pp.425-435
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• 2020

Numerous chemical modifications on activated carbon such as acidic conditioning, thermal treatment and metal impregnation have been investigated to enhance adsorption capacities of micropollutants in water treatment plants. In this study, chemical modification including acidic, alkaline treatment, and iron-impregnation was evaluated for adsorption of 2,4-dichlorophenol (2,4-DCP). For Fe-impregnation, three concentrations of ferric chloride solutions, i.e., 0.2 M, 0.4 M, and 0.8 M, were used and ion-exchange (MIX) of iron and subsequent thermal treatment (MTH) were also applied. Surface properties of the modified carbons were analyzed by active surface area, pore volume, three-dimensional images, and chemical characteristics. The acidic and alkaline treatment changed the pore structures but yielded little improvement of adsorption capacities. As Fe concentrations were increased during impregnation, the active adsorption areas were decreased and the compositional ratios of Fe were increased. Adsorption capacities of modified ACs were evaluated using Langmuir isotherm. The MIX modification was not efficient to enhance 2,4-DCP adsorption and the MES treatment showed increases in adsorption capacities of 2,4-DCP, compared to the original activated carbon. These results implied a possibility of chemical impregnation modification for improvement of adsorption of 2,4-DCP, if a proper modification procedure is sought.

• Korean Journal of Materials Research
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• v.33 no.10
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• pp.377-384
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• 2023

Exploring earth-abundant, highly effective and stable electrocatalysts for electrochemical water splitting is urgent and essential to the development of hydrogen (H₂) energy technology. Iron-cobalt layered double hydroxide (FeCo-LDH) has been widely used as an electrocatalystfor OER due to its facile synthesis, tunable components, and low cost. However, LDH synthesized by the traditional hydrothermal method tends to easily agglomerate, resulting in an unstable structure that can change or dissolve in an alkaline solution. Therefore, studying the real active phase is highly significant in the design of electrochemical electrode materials. Here, metal-organic frameworks (MOFs) are used as template precursors to derive FeCo-LDH from different iron sources. Iron salts with different anions have a significant impact on the morphology and charge transfer properties of the resulting materials. FeCo-LDH synthesized from iron sulfate solution (FeCo-LDH-SO₄) exhibits a hybrid structure of nanosheets and nanowires, quite different from other electrocatalysts that were synthesized from iron chloride and iron nitrate solutions. The final FeCo-LDH-SO₄ had an overpotential of 247 mV with a low Tafel-slope of 60.6 mV dec^-1 at a current density of 10 mA cm^-2 and delivered a long-term stability of 40 h for the OER. This work provides an innovative and feasible strategy to construct efficient electrocatalysts.

• Food Science and Preservation
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• v.30 no.6
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• pp.969-982
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• 2023

This study evaluated the impact of blanching pak choi stems and leaves in various solutions (distilled water, 2% NaCl, and 2% citric acid) at 100℃ on their quality characteristics. The highest stem heating loss was observed in the sodium chloride solution (S-NB) at 15.10% (p<0.001), and the highest leaf heating loss was in L-NB at 11.44% (p<0.001). No significant variation was found in the moisture content of both stems and leaves. Relative to the control, the L value (lightness) of the stem decreased while the b value (yellowness) increased (p<0.05). In the leaves, the a value (redness/greenness) and b value increased in L-CB, whereas they decreased in other groups (p<0.05). S-NB exhibited the highest true retention (TR) of total polyphenol content (TPC) in stems (p<0.01) and the highest TR of total flavonoid content (TFC) as well (p<0.001). For leaves, the highest TR of TPC and TFC was in L-WB (p<0.001). In terms of antioxidant activity, S-NB in stems and L-WB in leaves showed the highest scavenging activity measured by DPPH and ABTS⁺ assays (p<0.001). Microorganisms were absent in all pretreatment groups but present in the control. The results suggest that blanching pak choi stems in 2% NaCl solution and leaves in water optimally preserves biologically active compounds and nutrients.

• Journal of Life Science
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• v.12 no.1
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• pp.16-25
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• 2002

To summarize our interpretation of the results, we can explain shown below. Optimum con dictions in order to soften of sea tangle leafs were treated in the solutions of 0.05% $CH_3$COOH at 9$0^{\circ}C$ for 0.5 hour, 0.2% $K_2$HPO$_4$at 10$0^{\circ}C$ for 0.5 hour and 0.3% NaHCO$_3$at 10$0^{\circ}C$ for 0.5 hour. After sea tangle leafs were treated in the solutions of 0.05% $CH_3$COOH at 9$0^{\circ}C$ for 0.5 hour and added 10% seasoning agent of 0.5% glutamic acid, 3% glycine, 5% sorbitol and 1.5% soy sauce. Contents of free amino acid in the leaflike tea were a large amount as alanine of 707.2 $\mu$mo1/100$m\ell$ and glutamic acid of 343.6 $\mu$mo1/100 $m\ell$. And contents of mineral were order Na of 49.38 ppm, Mg of 10.72 ppm, K of 10.56 ppm and Ca of 6.55 ppm. Powder tea was added 0.05% glutamic acid, 5% glycine, 5% glucose and 4% sodium chloride in sea tangle powder, and then pressure treatment at 11$0^{\circ}C$ for 1.5 hours. Contents of free amino acid in the powder tea were a large amount as glycine of 222.04 $\mu$mo1/100$m\ell$ and glutamic arid of 208.58 $\mu$mol/100$m\ell$. And contents of mineral were order Na of 104.24 ppm, Mg of 14.31 ppm, K of 9.68 ppm, Fe of 2.36 ppm, Ca of 2.00 ppm, Zn of 0.13 ppm, Cu of 0.10 ppm and Mn of 0.01 ppm.

• YAKHAK HOEJI
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• v.42 no.3
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• pp.290-295
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• 1998

To optimize the formulation of acetaminophen liquid suppository, the effect of additives on the physicochemical properties of liquid suppository base was investigated. The physi cochemical properties of P 407/P 188 (15/15%) (abbreviated in 15/15) and P 407/P l88 (15/20%) (abbreviated in 15/20) were measured after the addition of following additives; 2.5% acetaminophen as an active ingredient, vehicle components (5% ethanol, 5% propylene glycol, 5% glycerin), preservatives (0.1% sodium benzoate, 0,1% methylparahydroxybenzoate, 0.1% propylparahydroxybenzoate) and 1% of sodium chloride as an ionic strength controlling agent. Poloxamer gel was prepared with three different buffer solutions (pH 1.2, 4.0 and 6.8) and the physicochemical properties, gelation temperature, gel strength and bioadhesive force, were determined. In the results, the effect of additives on the physicochemical properties was dependent on their bonding capacities including hydrogen bonding and cross-linking bonding. Because the hydrogen-bonding capacities of acetaminophen, ethanol and propylene glycol were smaller than that of poloxamer, the binding force of poloxamer gel became weak by their putting in between poloxamer gel. Therefore, the gelation temperature (15/15, $35.7^{\circ}C$ vs 37.0, 39.4 $38.2^{\circ}C$; 15/20, $29.2^{\circ}C$ vs 31.2, 32.0, $30.3^{\circ}C$) increased, and gel strength (15/15, 4.03 see vs 2.72, 2.08, 3.12sec; 15/20, 300g vs 50, 50, 200g) and bioadhesive force (15/15, $6.8{\times}10^2\;dyne/cm^2$ vs 3.2, 6.0, $6.0{\times}10^2\;dyne/cm^2$; 15/20, $97.3{\times}10^2\;dyne/cm^2$ vs 11.1, 89.5, $92.0{\times}10^2\;dyne/cm^2$) decreased. Furthermore, the binding force of poloxamer gel became strong due to the hydrogen-bonding capacities of glycerin and the cross-liking bonding of sodium salt. Then, the gelation temperature (15/15, 35.0, $32.1^{\circ}C$; 15/20, 26.0, $21.0^{\circ}C$) decreased, and gel strength (15/15, 6.51 see, 300g; 15/20, 500, 650g) and bioadhesive force (15/15, 7.2, $81.6{\times}10^2\;dyne/cm^2$; 15/20, 112.3, $309.2{\times}10^2\;dyne/cm^2$) increased. The effect of pH on the physicochemical properties of poloxamer gel was dependent on the ingredients with which the buffer solutions were prepared. Poloxamer gels prepared with pH 1.2 and 4.0 buffer solutions had the increasing gelation temperature (15/15, 37.5, $38.1^{\circ}C$; 15/20, 33.1, $34.0^{\circ}C$) and the decreasing gel strength (15/15, 2.98, 3.81sec; 15/20, 200, 200g) and bioadhesive force (15/15, $7.0{\times}10^2dyne/cm^2$; 15/20, $74.0{\sim}88.1{\times}10^2dyne/cm^2$) owing to HCl. Poloxamer gel prepared with pH 6.8 buffer solutions had the decreasing gelation temperature (15/15, $27.2^{\circ}C$; 15/20, $22.3^{\circ}C$) and the increasing gel strength (15/15, 400g; 15/20, 550g) and bioadhesive force (15/15, $207.0{\times}10^2dyne/cm^2$; 15/20, $215.0{\times}10^2dyne/cm^2$) due to the cross-linking bonding of $NaH_2PO_4\;and\;K_2HPO_4$.

• Journal of the Korean Geotechnical Society
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• v.20 no.7
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• pp.141-158
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• 2004

The dependency of criteria used to terminate compatibility tests on the prehydration and quality of bentonite in geosynthetic clay liners (GCLs) is evaluated based on permeation with chemical solutions containing 5, 10, 20, 50, and 100 mM calcium chloride ($CaCl_2$). The hydraulic conductivity tests are not terminated before chemical equilibrium between the effluent and the influent chemistry has been established, resulting in test durations ranging from < 1 day to > 900 days, with longer test durations associated with lower $CaCl_2$ concentrations. The evaluation includes both physical termination criteria (i.e., volumetric flow ratio and steady hydraulic conductivity based on ASTM D 5084, ${\ge}2$ pore volumes of flow, constant thickness of specimen) and chemical termination criteria requiring equilibrium between influent and effluent chemistry (viz., electrical conductivity, pH, and $Ca^{2+}\;and\;Cl^-$ concentrations). For specimens permeated with 5, 10, and 20 mM $CaCl_2$ solutions, only the criterion based on chemical equilibrium in $Ca^{2+}$ concentration correlates well with equilibrium in hydraulic conductivity, regardless of prehydration or quality of bentonite. However, all of the termination criteria, except for the volumetric flow ratio and 2 pore volumes of flow for the prehydrated specimens, correlate well with equilibrium in hydraulic conductivity regardless of prehydration or quality of bentonite when permeated with 50 and 100 mM $CaCl_2$ solutions. The results illustrate the uniqueness of the termination criterion based on solute concentration equilibrium between the effluent and the influent with respect to both prehydration and quality of bentonite in the GCLs.

• Journal of the Korean Wood Science and Technology
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• v.36 no.1
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• pp.110-123
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• 2008

The use of CCA as a wood preservative was recently inhibited due to its environmental pollution and human harmfulness. Instead of CCA, copper azole (CuAz) and alkaline copper quaternary (ACQ) have been used as alternative wood preservatives, but the price of the preservatives is much more expensive than that of CCA. As a substitute for high-priced CuAz and ACQ, environmentally friendly wood preservatives were formulated with okara, which is an organic waste from the production of tofu. Prior to formulating the preservatives, okara was hydrolyzed by three levels of sulfuric acid concentration (1, 2.5 and 5%) to easily penetrate the effective components of the preservatives into wood blocks. Final preservative solutions were formulated with the hydrolyzed okara and metal salts, such as copper sulfate, copper chloride and borax. The preservatives were treated into wood blocks by vacuum-pressure method to measure the treatability of the preservatives, and the treated wood blocks were placed in hot water for three days to measure the leachability of the preservatives. The effective components of the preservatives might be successfully penetrated into wood blocks through the uses of hydrolyzed okara and ammonia water. However, the leached amount of effective components was increased as the concentration of acid used for the hydrolysis of okara increased. The treatability and leachability of the preservatives were not affected by hydrolysis temperature but negatively affected by the addition of borax. Based on the results above, the optimal conditions for formulating okara-based wood preservatives cost-effectively and environmentally might be 1% acid hydrolysis of okara and the use of $CuCl_2$ as a metal salt. In addition, the treatability and leachability of okara-based wood preservatives were superior or no differences comparing with those of CuAz. Therefore, it is concluded that okara-based wood preservatives might have a potential to be used as an environmentally friendly wood preservative.