• Journal of Adhesion and Interface
• /
• v.14 no.1
• /
• pp.13-20
• /
• 2013

Palladium plays a pivotal role in the production of dental and medicinal devices, medicinal substances, jewellery, automobile and high-performance adhesives. Despite the frequent and fruitful use of such reactions, one major setback is the high level of palladium in the resultant compounds which can harm the human body. Among the palladium species, $PdCl_2$ is the most toxic. As a consequence it is desirable to detect the $Pd^{2+}$ cations by fluorescence spectra because it can provide an operationally simple and cost-effective detection method together with high sensitivity and selectivity. Herein, an ${\alpha}$-carbonyl substituted pyrene derivative, ${\gamma}$-oxo-1-pyrenebutyric acid (OPBA), was demonstrated to be a highly sensitive and selective fluorescent probe for $Pd^{2+}$ among the metal cations examined in aqueous solutions.

• Journal of the Korean Chemical Society
• /
• v.54 no.4
• /
• pp.374-379
• /
• 2010

The interaction of dichlorophenol isomers with the micellar system of TTAB (tetradecyltrimethylammonium bromide) was studied by the UV/Vis spectrophotometric method. The solubilization constants ($K_s$) of dichlorophenol isomers into the micellar system have been measured with the change of temperature and the various thermodynamic parameters have been calculated and analyzed from these changes. The results show that the values of ${\Delta}G^{\circ}_s$ and ${\Delta}H^{\circ}_s$ are all negative within the measured temperature range. The effects of additives (n-butanol and NaCl) on the solubilization of dichlorophenol isomers have been also measured. There was a great change on the values of $K_s$ and CMC simultaneously with these additives. From these changes we can postulate the solubilization sites of each isomers in the micellar system of TTAB.

• Korean Chemical Engineering Research
• /
• v.51 no.3
• /
• pp.347-351
• /
• 2013

The preparation of glycerol carbonate (GC) from urea through carbonylation with renewable glycerol was investigated by using ionic liquid catalysts. It was found that quaternary ammonium salt and imidazolium salt ionic liquids with a shorter alkyl chain length and higher nucleophilic anion showed better catalytic performance. The effects of reaction temperature, reaction time and degree of vacuum on the reactivity of TBAC catalyst ware discussed. Zinc chloride ($ZnCl_2$) was used as co-catalyst with the ionic liquid catalyst. The mixed catalyst showed a synergy effect on the glycerol conversion and GC yield probably due to the acid-base properties of the catalysts.

• Journal of the Korean Geotechnical Society
• /
• v.23 no.2
• /
• pp.29-34
• /
• 2007

This study examines the effects of heat treatment under laboratory conditions for mixtures of two types of clay (kaolinite and montmorillonite). Clay samples were burned with different temperatures ranging from $100^{\circ}C\;to\;500^{\circ}C$. The Atterberg limits such as liquid and plastic limits were influenced with heat treatment. According to the experimental results, the liquid limits slightly decreased between $100^{\circ}C\;to\;300^{\circ}C$, whereas rapid decreases were observed after $300^{\circ}C$. The plastic limits did not show noticeable differences in the interval $100^{\circ}C\;to\;400^{\circ}C$. But the clay samples showed non plastic behavior at $500^{\circ}C$. The amount of NaCl was getting decreased with temperature. It also revealed that the pH values were also influenced with heat treatment, and the cation exchange capacity (C.E.C) values decreased with temperature.

• Journal of the Korea Institute of Building Construction
• /
• v.23 no.5
• /
• pp.559-570
• /
• 2023

The corrosion of structural steel used in the construction industry is increasing due to the industrialization where many aggressive ions released in the atmosphere. Therefore, in the present study Al coating was deposited by arc and plasma arc thermal spray process and compared their effectiveness in simulated weathering condition i.e. Society of Automotive Engineers(SAE) J2334 solution which mostly contain Cl^- and CO₃^2- ions. Different analytical techniques have been used to characterize the coating and draw the corrosion mechanism. The Al coating deposited by plasma arc thermal spray process exhibited uniform, dense and layer by layer deposition resulting higher bond adhesion values. The open circuit potential(OCP) of Al coating deposited this process is exhibited more electropositive values than arc thermal spray process in SAE J2334 solution with immersion periods. The total impedance of plasma arc thermal spray process exhibited higher than arc thermal spray process. The corrosion rate of the plasma arc thermal sprayed Al coating is reduced by 20% compared to arc thermal spray process after 23 days of immersion in SAE J2334 solution.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.27 no.5
• /
• pp.16-22
• /
• 2023

In this study, a salt water immersion test was performed on concrete specimens simulating the concrete mix design of the nuclear power plant, and the correlation between the amount of chloride and the XRF component according to the depth of the concrete was analyzed. The amount of chloride on the surface of the nuclear power plant concrete increased slightly with increasing immersion time in salt water, but the amount of chloride in the depth of 5.5 mm or more showed a clear tendency to increase with increasing immersion time in salt water. As a result of analyzing the correlation between the amount of chloride in concrete and the XRF component, the concrete with 20% FA substitution compared with the OPC concrete showed a very high correlation between the composition ratio of Cl ions and the evaluation result of salt damage resistance by XRF component analysis. Accordingly, it was confirmed that chlorine ion analysis and salt damage resistance performance evaluation by XRF component analysis were possible through repeated data accumulation in the nuclear power plant concrete mix with 20% fly ash replacement.

• Journal of the Korean Chemical Society
• /
• v.17 no.6
• /
• pp.406-410
• /
• 1973

Kinetic study of halide exchange for dimethylsulfamoyl chloride in dry acetone by using radioisotopic halide ions has been carried out at two temperatures. The result of the order of nucleophilicity, as compared with benzenesulfonyl chloride, shows a similar tendency but reaction rate is slower, more than $10^{-2}$times, than benzenesulfonyl chloride. The activation parameter, ${\Delta}H^{\neq}\;and\;{\Delta}S^{\neq}$ decrease in sequence $Cl^-\;>\;Br^-\;>\;I^-$ in dimethylsulfamoyl chloride but it is the reverse order found for benzenesulfonyl chloride. The results are interpreted with bond-breaking, bond-formation, and electronic requirments, and in the light of HSAB Principle.

• Microbiology and Biotechnology Letters
• /
• v.17 no.5
• /
• pp.407-411
• /
• 1989

Extracellular neutral pretense of Streptomyces rimosus producing oxytetracycline was purified by ammonium sulfate fractionation, DEAE Sephadex A-50 chromatography and Sephadex G-100 gel filteration, and was showed single band on the cathodic gel electrophoresis. The optimum pH and temperature of the enzyme were pH 8.0 and 6$0^{\circ}C$, respectively. The enzyme was activated about 80% in the presence of Co$^{2+}$ ion, and strongly inhibited by Hg$^{2+}$, Fe$^{2+}$ and chelatig agent, EDTA. Molecular weight of the enzyme was estimated to be 12, 000. The Km value of the enzyme of casein as a substrate was 2.7$\times$10$^{-4}$M.

• Journal of the Korean Chemical Society
• /
• v.32 no.2
• /
• pp.130-134
• /
• 1988

Direct differential-pulse cathodic stripping voltammetry on mercury electrode (HMDE) provides a sensitive technique for low level cyanide measurement in distilled and sulfide free solution. Cyclic voltammetry revealed the forming and redissolution reactions were reversible at pH 7 in 0.1M KCl-0.01M phosphate supporting electrolyte. The analytical conditions have been optimized. With deposition time of 3 min at deposition potential 0.00V(vs. Ag/AgCl) in this medium of pH7, quite reproducible and linear calibration curve was obtained down to $3{\times}10^{-7}M$ (8ppb) $CN^-$ which was the detection limit.

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