• Journal of the Korean Chemical Society
• /
• v.53 no.5
• /
• pp.485-490
• /
• 2009

The inhibitive action of the aqueous extract of lawsonia, licorice root and carob toward the corrosion of tin electrode in 0.1 M $NaHCO_3$ solutions was investigated using galvanostatic polarization measurements. It was found that the corrosion rate decreases in the presence of these extracts indicating the inhibiting of these compounds. The inhibition efficiency increases with increasing extract concentration. The inhibition action of these extracts was explained in view of adsorption of its compounds onto the tin surface, making a barrier to mass and charge transfer. The adsorption of these extracts on the tin surface was found to be a spontaneous process and follow Freundlich adsorption isotherm. It is also found that these extracts provide a good protection to tin against pitting corrosion in chloride containing solution using potentiodynamic anodic polarization technique.

• Journal of the Korean Applied Science and Technology
• /
• v.36 no.2
• /
• pp.407-416
• /
• 2019

The criticical micelle concentration (CMC) was measured by using the UV-Vis method for the micellization of the ammonium type cationic surfactants (DTAB, TTAB, and CTAB) in the aqueous aniline solution. The enthalpy change (${\Delta}H^0$) and entropy change (${\Delta}S^0$) were calculated from the dependence of Gibbs free energy change (${\Delta}G^0$) on the temperature for micellization of the cationic surfactants between 290K and 314K. The effects of n-butanol and sodium chloride on the micellization of cationic surfactants were measured and compared with the other thermodynamic functions. All the free energy changes (${\Delta}G^0$) of the micellization were negative, all the enthalpy change (${\Delta}H^0$) were negative, and all the entropy change (${\Delta}S^0$) were positive values, respectively. The micelle formation of cationic surfactant in aniline solution is a spontaneous exothermic reaction, and the iso-structural temperature calculated from the thermodynamic values show that enthalpy and entropy contribution to the micellization are almost the same for the micellization of cationic surfactants

• Korean Chemical Engineering Research
• /
• v.48 no.2
• /
• pp.275-282
• /
• 2010

A characteristic study of aqueous chlorine dioxide generation from sodium chlorite($NaClO_2$) by an undivided electrochemical cell with different anode materials were performed. $IrO_2$-coated Ti, $RuO_2$-coated Ti and DSA were used as anode materials and Pt-coated Ti electrode was used as cathode. Various electrochemical cell operating parameters such as cell residence time($t_R$), initial feed solution pH, sodium chlorite and sodium chloride(NaCl) concentration and applied current for the generation of chlorine dioxide in an un-divided cell were investigated and optimized. Estimated optimal cell residence times in $IrO_2$-coated Ti, $RuO_2$-coated Ti and DSA anode material systems were around 2.27, 1.52 and 1.52 sec, respectively. Observed optimum initial feed solution pH was around 2.3 in all anode material systems. Optimum sodium chlorite concentrations in $IrO_2$-coated Ti, $RuO_2$-coated Ti and DSA anode systems were around 0.43, 0.43 and 0.32 g/L, respectively. Optimum electrolyte concentration and applied current were around 5.85 g/L and 0.6 A in all anode systems. Current efficiencies of $IrO_2$-coated Ti, $RuO_2$-coated Ti and DSA anode systems under optimum conditions were 79.80, 114.70 and 70.99%, respectively. Obtained energy consumptions for the optimum generation of chlorine dioxide were 1.38, 1.03 and $1.61W{\cdot}hr/g-ClO_2$, respectively.

• Korean Chemical Engineering Research
• /
• v.46 no.2
• /
• pp.330-339
• /
• 2008

Effect of additives such as NP series nonionic surfactant and cosurfactant on AgCl nanoparticles was investigated where nanoparticles were prepared using two different types of water-in-oil (W/O) microemulsions containing silver nitrate and sodium chloride, respectively. Phase behavior experiments showed that the region of one phase W/O microemulsion was found to be broadened with an increase in the ethylene oxide length of a nonionic surfactant mainly due to an increase in hydrophilic nature of a surfactant. Photomicrographs obtained by transmission electron microscopy indicated that an increase in ethylene oxide length of a nonionic surfactant results in both increases in particle size and size distribution. Phase behavior experiments for the systems containing AOT surfactant, isooctane and aqueous solution of an inorganic salt showed that addition of a cosurfactant caused a shrinkage in phase region of one phase W/O microemulsion, especially water contents contained in W/O microemulsion with an increase in the chain length or the concentration of a cosurfactant used. Photomicrographs obtained by transmission electron microscopy indicated that characteristics of AgCl nanoparticles produced were dependent both on the radius of spontaneous curvature and film rigidity of a microemulsion.

• Journal of Food Hygiene and Safety
• /
• v.37 no.5
• /
• pp.317-322
• /
• 2022

Corynebacterium pseudotuberculosis is the causative agent of caseous lymphadenitis (CLA), a chronic contagious disease in small ruminants. The prevalence of CLA has been reported to be >50% in Korean black goats. CLA is difficult to control due to a lack of efficient vaccines and treatment methods. Effective disinfection of the farm environment may be an alternative strategy for reducing the spread of C. pseudotuberculosis. The objective of this study was to evaluate the efficacy of commercial disinfectants against CLA. The six commercial disinfectants, largely composed of sodium dichloroisocyanurate, sodium hypochlorite, potassium monopersulfate triple salt, quaternary ammonium, citric acid, and copper sulfate, were tested against five different genotypes of C. pseudotuberculosis isolated from goat farms in Korea. Efficacy tests were performed in accordance with the disinfectant efficacy test guidelines recommended by the Animal and Plant Quarantine Agency of Korea with slight modifications. All disinfectants except for copper sulfate exhibited >99.99% killing efficacy under hard water conditions following 30 min of incubation, which is the recommended standard treatment time according to guidelines. The minimum bactericidal treatment time was evaluated by employing treatments for durations of 1, 5, and 15 min. The most effective compounds under hard water conditions were sodium dichloroisocyanurate, potassium monopersulfate triple salt, and sodium hypochlorite, exhibiting >99.99% killing efficacy after 1 min of treatment. In the aqueous solution forms, citric acid and the quaternary ammonium compound were the most effective, but required at least 5 min to kill >99.99% of the bacteria. The current study characterizes the killing efficacy of six commercial disinfectant active compounds against C. pseudotuberculosis. Thus, this study provides essential information regarding the efficacy of the disinfectants used to control CLA in goat farms.

• Analytical Science and Technology
• /
• v.21 no.6
• /
• pp.518-525
• /
• 2008

Mandipropamid is a new mandelamide-type fungicide to control foliar Oomycete pathogens in some vegetables. An analytical method was developed to determine mandipropamid residues in agricultural commodities using high-performance liquid chromatography (HPLC) and liquid chromatography/mass spectrometry (LC/MS). Mandipropamid was extracted with methanol from grape, tomato, green pepper, Chinese cabbage and potato samples. The extract was diluted with saturated sodium chloride solution and distilled water, and dichloromethane partition was followed to recover the mandipropamid from the aqueous phase. Florisil column chromatography was employed to further remove interfering co-extractives prior to HPLC analysis. Reverse-phased HPLC was successfully applied to determine mandipropamid in sample extracts with the detection at its ${\lambda}_{max}$ (223 nm). Overall recoveries of mandipropamid from fortified samples averaged $99.8{\pm}1.7$ (n=6), $89.3{\pm}5.3$ (n=6), $98.7{\pm}2.2$ (n=6), $99.7{\pm}6.8$ (n=6) and $91.1{\pm}3.1$ (n=6) for grape, tomato, green pepper, Chinese cabbage and potato, respectively. Limit of quantification of the method was 0.02~0.04 mg/kg for all samples. A LC/mass spectrometry with selected-ion monitoring was also provided to confirm the suspected residue. The proposed method was reproducible and sensitive enough to determine the terminal residue of mandipropamid in agricultural commodities.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.14 no.2
• /
• pp.94-102
• /
• 1981

To investigate the characteristics of anodic film formed on metals and the reactivities of organic inhibitor Di-iso-butylnitrosoamine (DBNA) in sea water. the cathodic reactions of anodic film formed on metals were carried out by using the potential drop method and galvanostatic method at $25^{\circ}C$. The investigated results are as follows: The anodic films formed on aluminum and zinc in 60mM $DBNA+9\%_{\circ}$ sea water did not show-changes of potential drop. However, those formed on lead and copper were reasonable electrodes. It was concluded that cathodic reactivities of proton through the anodic film in aqueous solution were constant without regard to the kinds of metals used with anodic film electrode at operated current density ranges, because the values of transition time obtained in 0.5M sodium chloride solution and $9\%_{\circ}$ sea water nearly coincided. The values of transition time of the first step by the galvanostatic method were obtained from 0.22 to 1.40 sec ranges far less than one minute. Therefore, it suggested that cathodic reactions of proton through the anodic film were mainly controlled by diffusion/adsorption process. The differences of between $\tau_{1}/4$ in $9\%_{\circ}$ sea water and $\tau_{1}/4$ in 60mM $DBNA+9\%_{\circ}$ sea water, and between $E_{1}/4$ in sea water and $E_{1}/4$ in 60mM $DBNA+9\%_{\circ}$ sea water at the constant current density with $1.9\times10^{-4}\sim5.0{\times}10^{-6}\;amp/cm^2$ were 0.06 sec and 0.53 v. respectively and cathodic reactions of DBNA on the anodic film electrodes were chiefly controlled by adsorption/diffusion process. The reason that adsorption quantities of proton on anodic film formed on aluminum and zinc in aqueous solutions were much more than those on lead and copper, seems to lie due mostly to the number of porosity produced on anodic film used.