• Bulletin of the Korean Chemical Society
• /
• v.30 no.12
• /
• pp.3107-3108
• /
• 2009

• Bulletin of the Korean Chemical Society
• /
• v.8 no.1
• /
• pp.50-51
• /
• 1987

• Bulletin of the Korean Chemical Society
• /
• v.6 no.3
• /
• pp.175-176
• /
• 1985

• Applied Chemistry for Engineering
• /
• v.20 no.6
• /
• pp.696-699
• /
• 2009

In present work, the antimicrobial effect of silver-nanoparticles/celite (SN/C) and silver carbonate/celite (SC/C) composites on Escherichia coli (E. coli) by use of silver nanoparticles and silver carbonate has been studied. Characteristics of the SN/C and SC/C composites were identified by scanning electron microscopy (SEM), X-ray diffraction (XRD) and atomic absorption spectroscopy (AAS). SN/C and SC/C composites showed antimicrobial activity and the minimum inhibitory concentration of E. coli were 0.541, 0.344 ppm and the complete sterilizing concentration for the test organism were 1.427, 1.623 ppm. From the results we identified that SN/C and SC/C composites have antimicrobial activity to E. coli.

• Journal of the Korean Chemical Society
• /
• v.32 no.4
• /
• pp.351-357
• /
• 1988

The electrochemical reduction of uranyl ion at the dropping mercury electrode and/or mercury microelectrode has been studied in propanediol-1,2-carbonate (PDC) by voltammetric techniques. The position of peak potentials, the nature of limiting currents, their dependency on temperature and on concentrations, reversibility of electrode reactions, and influence of addition of phenol are described. The influence of PDC in aqueous solution of uranyl ion was also described. The values of kinetic parameters, viz., transfer coefficient, formal constant for the electrode reactions bave been determined by Koutecky's method as extended by Meites and Israel. The values of ${\Delta}H,\;{\Delta}G\;and\;{\Delta}S$ have also been calculated.

• Journal of Korean Society on Water Environment
• /
• v.26 no.3
• /
• pp.525-531
• /
• 2010

To figure out the importance of temperature on electrochemical properties in water environment, calcium carbonate, one of important substances in water chemistry, was chosen to make suspensions. The result of electrokinetic potential of calcium carbonate suspensions revealed that it tended to increase as temperature increased. In addition, electrokinetic potential was negatively increased as suspensions became more basic. Its isoelectric point was ca. 7 regardless of temperature. The adsorption of hydrogen ions on calcium carbonate particles followed endothermic reaction. This result was verified by continuously measuring pH as adding HCl solution in calcium carbonate suspension. It explained that suspensions' potential was determined by DLVO theory which calculated total interaction energy between particles. Suspensions' total interaction energy was proportional to the value of electrokinetic potential. Furthermore, total interaction energy between particles increased as suspensions' temperature was increased.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.2 no.2
• /
• pp.109-112
• /
• 1997

Morphology of carbonate crystals grown on the surface of artificial cell membranes was controlled by changing the interfacial chemistry. For octadecyltriethoxysilane (OTE) films with terminal methyl groups interacting little with an aqueous calcium carbonate solution calcite (104) crystals were formed. Polymerized pentacosadiynoic acid (PDA) films with terminal carboxylic acid groups induced deposition of calcite (012) crystals aligned along with each other within a polymer domain. On the other hand, stearyl alcohol (StOH) films with terminal hydroxyl groups induced deposition of aragonite crystals. When PDA was mixed with StOH, the 8:1 PDA:StOH (molar ratio) film produced dominating calcite (012) crystals without any crystal alignment, and the 4:1 mixture film produced minor calcite (012) crystals and major aragonite crystals. For the 2:1, 1:1, 1:2, and 1:4 mixture films, aragonite crystals were dominating. Hence, it is found that the chemical composition at the interface plays a very important role in controlling the morphology of deposited carbonate crystals.

• Bulletin of the Korean Chemical Society
• /
• v.27 no.1
• /
• pp.82-86
• /
• 2006

Propylene Carbonate (PC) has the interesting properties of being able to dissolve and dissociate lithium salts, thus leading to highly conducting electrolytes even at low temperatures. Moreover, electrolytes that contain PC are stable against oxidation at voltages up to ~5 V. However, it is known that, when lithium is intercalated into graphite in pure PC based electrolytes, solvent co-intercalation occurs, leading to the destruction of the graphite structure. (i.e., exfoliation). The objective of this study was to suppress PC decomposition and prevent exfoliation of the graphite anode by co-intercalation. Electrochemical characteristics were studied using Kawasaki mesophase fine carbon (KMFC) in different 1 M $LiPF_6$/PC-based electrolytes. Electrochemical experiments were completed using chronopotentiometry, cyclic voltammetry, impedance spectroscopy, X-ray diffraction, and scanning electron microscopy. From the observed results, we conclude that the MA and $Li_2CO_3$ additive suppressed co-intercalation of the PC electrolyte into the graphite anode. The use of additives, for reducing the extent of solvent decomposition before exfoliation of the graphite anode, could therefore enhance the stability of a KMFC electrode.

• Journal of Adhesion and Interface
• /
• v.9 no.2
• /
• pp.24-31
• /
• 2008

In this work, calcium hydroxide and magnesium carbonate as metal ionic crosslinking agents were used to introduce ionic crosslinking points to the ethylene vinylacetate (EVA) emulsions for the enhancement of water resistance and mechanical properties of emulsion films. The properties of EVA emulsion film were investigated in crosslinking density, thermal features, surface energy, and mechanical properties, such as tensile strength, elongation at break and tear strength. With the increasing content of metal ionic crosslinking agent, the crosslinking density of the EVA emulsion film increases, resulting into the improvement of water resistance. The surface energy and mechanical properties of the EVA emulsion film, however, showed somewhat different behaviors. The highest surface energy, tensile strength, and tear strength were observed when 0.4% for calcium hydroxide and 0.5% for magnesium carbonate was added respectively, because the EVA emulsion containing carboxylic acid forms strong carboxylate-metal bond of ionically-crosslinked system. Therefore, it can be concluded that metal ionic crosslinking agents, such as magnesium carbonate and calcium hydroxide are considered to improve water resistance and mechanical properties of the EVA emulsion.

• Applied Chemistry for Engineering
• /
• v.19 no.2
• /
• pp.209-213
• /
• 2008

The fixed bed gasification reactor with 1 m hight and 10.2 cm diameter was utilized for the hydrogen production from biomass wastes. Lauan sawdust was used for non-catalytic and catalytic gasification reaction as a sample in the fixed bed reactor. The fixed bed temperature and catalyst are the major variables affecting the process operation. Thus, the effect of fixed bed temperature and the catalysts on gas composition were studied at the temperature range from $400^{\circ}C$ to $700^{\circ}C$. The yield of hydrogen was increased at higher temperature in the fixed bed reaction. Fractions of hydrogen, carbon monoxide and methane gas in the product gas increased when sodium carbonate ($Na_2CO_3$) and potassium carbonate ($K_2CO_3$) catalysts were used. Furthermore, sodium carbonate catalyst was more effective to obtain higher hydrogen yield compared to potassium carbonate catalyst.