• Journal of Korean Society of Environmental Engineers
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• v.39 no.7
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• pp.412-417
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• 2017

Removal characteristics of methyl orange and their dependence on operating parameters in a catalytic ozonation were investigated through a series of batch experiments. Activated carbon enhanced the self-decomposition of ozone, generating $OH{\cdot}$, thus promoting methyl orange degradation. As the carbon dose increases, the pseudo-first order rate constants of methyl orange degradation increased, resulting in the fast removal of methyl orange. The increase of gaseous ozone concentration enhanced the mass transfer to the aqueous solution, therefore, promoted the methyl orange removal. The methyl orange degradation was not significantly affected by the change of pH in the range of 5~12, and TOC removal was negligibly affected by the variation of pH over 7. The results indicate that the catalytic ozonation can be considered as an effective dye treatment technology.

• Korean Journal of Food Science and Technology
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• v.46 no.3
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• pp.276-282
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• 2014

An accurate and sensitive analytical method was established for the simultaneous determination of synephrine and n-methyltyramine contents by ultra-performance liquid chromatography (UPLC) with a fluorescence detector (FLD). A 70:30 (v/v) mixture of 10 mM sodium dodecyl sulfate (SDS) and acetonitrile was used as the mobile phase. The coefficient of correlation ($r^2$) was 0.9999 for both synephrine and n-methyltyramine, and their limits of detection (LOD) were 0.02 and 0.01 mg/kg, respectively. The percentage recoveries for synephrine and n-methyltyramine were 96.4% and 100.9%, respectively, from bitter orange (Citrus aurantium) samples. The synephrine and n-methyltyramine contents were 38.07-118.21 mg/kg and 0.27-0.56 mg/kg, respectively, in the orange fruit samples, while they were 14.61-120.39 mg/kg and up to 3.34 mg/kg, respectively, in the tested commercial orange juice samples. The differences in synephrine and n-methyltyramine content between orange fruit and commercial orange juice were not significant (p<0.05). These results suggest that UPLC-FLD can be applied to develop an analytical method of quality control for commercial orange juice.

• Korean Chemical Engineering Research
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• v.55 no.5
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• pp.718-722
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• 2017

We have investigated the photocatalytic activity for the decomposition of methyl orange on the pure $LaCoO_3$ and metal ion doped $LaCoO_3$ perovskite-typeoxides prepared using microwave process. In the case of pure $LaCoO_3$ and cesium ion doped $LaCoO_3$ catalysts, the formation of the perovskite crystalline phase was confirmed regardless of the preparation method. From the results of UV-Vis DRS, the pure $LaCoO_3$ and cesium ion doped $LaCoO_3$ catalysts have the similar absorption spectrum up to visible region. The chemisorbed oxygen plays an important role on the photocatalytic decomposition of methyl orange and the higher the contents of chemisorbed oxygen, the better performance of photocatalyst.

• Journal of Applied Biological Chemistry
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• v.54 no.3
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• pp.214-217
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• 2011

Fumigant, methyl bromide which is used in most countries for plant quarantine, has been designated and under control as ozone depleting substance. For developing alternative chemicals for methyl bromide, many countries have been intensifying their capacity. This study was carried out to investigate the residue patterns of hydrogen cyanide which is commonly used for plant quarantine. Hydrogen cyanide was treated onto the orange, banana, and pineapple at recommended and double doses and then sampling was done at 1 and 3 day after fumigation treatment. Residue of hydrogen cyanide was found safe because average residue levels on orange, banana, and pineapple after 3 days of fumigation treatment were $0.57{\pm}0.05$, $0.21{\pm}0.17$, and $0.41{\pm}0.08$ ppm, which were lower than the MRLs of Korea (5 ppm), Japan (5 ppm), USA (50 ppm), and Canada (25 ppm). Hydrogen cyanide are expected to be used as alternative chemicals for methyl bromide fumigant for orange, banana, and pineapple.

• Journal of the Korean Chemical Society
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• v.66 no.3
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• pp.251-255
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• 2022

• Journal of Korean Society of Water and Wastewater
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• v.26 no.1
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• pp.69-76
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• 2012

A laboratory experiment on methyl orange degradation in pulsed corona discharges was carried out. Effects of operating parameters such as applied voltage, pH, conductivity and initial concentration on methyl orange degradation were investigated. The pulsed corona discharges decreased the pH of solution and increased conductivity, probably due to products generated from methyl orange degradation by corona discharges. The decrease of initial pH enhanced the methyl orange degradation. The methyl orange degradation was fastest in $100{\mu}S/cm$ conductivity solution, followed by 50 and $200{\mu}S/cm$, indicating that $100{\mu}S/cm$ is the most favorable in the aspect of radical generation among the experimented conditions. The methyl orange of initial concentration from 20 to 60mg/L was effectively degraded in pulsed corona discharges. The lower initial concentration of methyl orange, the faster degradation was observed.

• Applied Chemistry for Engineering
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• v.1 no.2
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• pp.182-189
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• 1990

Various crosslinked poly(4-vinylpyridines) having different degrees of crosslinking were prepared by radical copolymerizations of 4-vinylpyridine with N, N'-2, 6-pyridinebisacrylamide as a crosslinker. The abilities of these crosslinked polymers to bind methyl orange and butyl orange were investigated at various temperatures in a buffer solution of pH 7. The first binding constants were evaluated from the equilibrium binding amounts. The first binding constants against the temperatures showed bell-shaped curves. Also, the first binding constants against the degree of crosslinking showed bell-shaped curves. When the temperature and the degree of crosslinking of maximum binding in the curves of these binding systems were compared with those of previous systems containing crosslinked poly(4-vinylpyridines) prepared by using N, N'-methylenebisacrylamide, N, N'-tetramethy-lenebisacryamide and divinylbenzene as crosslinkers, respectively, they were varied with the crosslinked poly(4-vinyl pyridines) containing different crosslinkers. These results were discussed in terms of the properties of the crosslinkers.

• Journal of the Korean Chemical Society
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• v.40 no.4
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• pp.273-277
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• 1996

• Proceedings of the Korean Fiber Society Conference
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• 1987.06a
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• pp.47-48
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• 1987

• Clean Technology
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• v.26 no.4
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• pp.311-320
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• 2020

In this study, the photocatalytic degradation of rhodamine B (RhB), methyl orange (MO) and methylene blue (MB) was carried out under visible light irradiation using CdS and CdZnS/ZnO photocatalysts prepared by a simple precipitation method. This study focused on examining the effect of physicochemical properties of dye and photocatalyst on the reaction pathway of photocatalytic degradation. The prepared photocatalysts were characterized by XRD, UV-vis DRS and XPS. Both the CdS and CdZnS/ZnO photocatalysts exhibit an excellent absorption in the visible light and the UV light regions. It was observed that the photocatalytic degradation of MO proceeds via the same reaction mechanism on both the CdS and CdZnS/ZnO photocatalysts. However, the photocatalytic degradation of RhB and MB was found to proceed through a different reaction pathway on the CdS and CdZnS/ZnO catalysts. It is interesting to note that MB dimer was formed on the CdS catalyst at the beginning of the photocatalytic reaction, while the MB monomer was degraded during the overall photocatalytic reaction on CdZnS/ZnO. The above results may be mainly ascribed to the difference of band edge potential of the conduction band in the CdS and CdZnS/ZnO semiconductors and the adsorption property of dye on the catalysts.