• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.229-233
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• 2022

In this study, a gas-liquid hybrid atmospheric pressure plasma reactor of the dielectric barrier discharge method was fabricated and characterized. The solubility of copper oxide in the organic acid solution was increased when argon having a larger atomic weight than helium was used during plasma discharge. There was no significant effect of mixing organic acid solutions under plasma discharge treatment on the variation of copper oxide's solubility. As the applied voltage for plasma discharge and the concentration of the organic acid solution increased, the dissolution and removal power of the copper oxide layer increased. Solubility of copper oxide was more affected by the concentration in organic acid solution rather than the variation of plasma applied voltage. The usefulness of hybrid plasma reactor for the surface cleaning process was confirmed.

• Korean Journal of Plant Resources
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• v.33 no.3
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• pp.194-199
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• 2020

This study was carried out to get the information of Plum tree (192 germplasm) collected in Korea, and to evaluate the organic acid contents and fermentation solution. The organic acid content of fruit was 50.9 ± 6.0 mg/g, and which was composed of 55.5% of citric acid, 43.4% of malic acid and 1.1% of oxalic acid, and showed large difference among germplasms. Oxalic acid and malic acid made no differences in organic acid content according to flesh color, whereas citric acid and total organic acid contents were highest in orange color and lowest in whitish green. Malic acid, citric acid and total organic acid contents did not show differences among fruit weight groups, but oxalic acid content was highest at fruit weight of 5.1 ~ 10.0 g and lowest at more than 20.1 g. The sugar content of fermentation solution of fruit was 55.7 ± 1.6 °Brix and the harvest rate was 116.7 ± 8.7%. The correlation coefficients among fruit weight, the sugar content (°Brix) and harvest rate of fermentation solution were very low, and there were correlations of r=-0.551^⁎⁎ between fruit weight and oxalic acid, r=-0.767^⁎⁎ between malic acid and citric acid, and r=0.834^⁎⁎ between citric acid and total organic acid content.

• Applied Chemistry for Engineering
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• v.7 no.6
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• pp.1204-1208
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• 1996

The organic impurities are formed in the p-xylene oxidation process to terephthalic acid(TPA) and they are present in the filtrate(mother liquor) solution or the TPA particles. The organic impurities present in the p-xylene oxidation are formed through side reactions or incomplete reaction. In this study, the main organic impurities, such as benzoic acid, p-toluic acid, p-tolualdehyde, 4-carboxybenzaldehyde, phthalic acid, isophthalic acid, trimellitic acid, and 4-hydroxymethyl benzoic acid were identified simultaneously by gas chromatograghy. The above impurities were reacted with bis(trimethylsilyl)trifluoroacetamide in the mixture of internal standard solution and pyridine solution by trimethylsilylation, where the internal standard solution was made by 99% bis (trimethylsilyl)trifluoroacetamide and 1% trimethylchlorosilane. The main organic impurities above mentioned can be analyzed quantitatively within 50 min.

• Applied Chemistry for Engineering
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• v.10 no.6
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• pp.907-912
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• 1999

In this study, removal effect of residue pesticides on vegetable and fruit using organic acid salt in alkali solution were investigated by gas chromatography and measurement of detergency. Generally, for the removal methods of residue pesticides and oily pollution were used chemical detergent or organic solvent. Specially, in our experiment, we only used material of food additives and trisodium citrate were superior to other organic acid salt. It was investigated that removal effect of pesticides was superior to chemical detergent.

• Journal of Microbiology and Biotechnology
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• v.3 no.2
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• pp.129-133
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• 1993

The effect of different compositions of organic acids on the flavor profile of 10% sugar solution was investigated by the response surface methodology, and the results were used to evaluate the flavor characteristics of lactic acid fermented cereal beverages. A mixture of extruded rice flour (10%) and soymilk (7.8% dry matter) was fermented with Leuconostoc mesenteroides (Sikhae). Depending on the substrate pretreatments, for example, the malt or amylase digestion and the proteolytic enzyme hydrolysis, the sugar and organic acid composition of the product varied. The organic acid composition of the fermented beverages was in the ranges of 0.44-0.55% lactic acid, 0.05-0.09% acetic acid and 0.07-0.09% citric acid, while that of commercial apple juice was 1.59% malic acid and 0.49% acetic acid. The flavor profiles of fermented beverages added with 10% sucrose were compared to those of apple juice and a model mixture containing 0.48% citric acid, 0.39% lactic acid and 0.12% acetic acid in 10% sugar solution. The QDA diagram of fermented beverages approached to that of apple juice, when the substrate was digested by amylase but not by protease.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.2
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• pp.99-103
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• 2008

To improve efficiency of solar cells, it is important to make a light trapping structure to reduce surface reflectance for increasing absorption of sun light within the solar cells. One of the promising methods that can reduce surface reflectance is isotropic texturing with acid solution based on hydrofluoric acid(HF), nitric acid($HNO_3$), and organic additives. Anisotropic texturing with alkali solution is not suitable for multicrystalline silicon wafers because of its different grain orientation. Isotropic texturing with acid solution can uniformly etch multicrystalline silicon wafers unrelated with grain orientation, so we can get low surface reflectance. In this paper, the acid texturing solution is made up of only HF and $HNO_3$ for easy controlling the concentration and low cost compared to acid solution with organic additives. $HNO_3$ concentration and dipping time were varied to find the condition of minimum surface reflectance. Textured surfaces were observed Scanning Electron Microscope(SEM) and surface reflectance were measured. The best result of arithmetic mean(wavelength from 400 nm to 1000 nm) reflectance with acid texturing is 4.64 % less than alkali texturing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.16-17
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• 2007

To improve efficiency of solar cells, it is important to make a light trapping structure to reduce surface reflectance for increasing absorption of sun light within the solar cells. One of the promising methods that can reduce surface reflectance is isotropic texturing with acid solution based on hydrofluoric acid(HF), nitric acid($HNO_3$), and organic additives. Anisotropic texturing with alkali solution is not suitable for multicrystalline silicon wafers because of its different grain orientation. Isotropic texturing with acid solution can uniformly etch multicrystalline silicon wafers unrelated with grain orientation, so we can get low surface reflectance. In this paper, the acid texturing solution is made up of only HF and $HNO_3$ for easy controling the concentration and low cost compared to acid solution with organic additives. $HNO_3$ concentration and dipping time were varied to find the condition of minimum surface reflectance. Textured surfaces were observed Scanning Electron Microscope(SEM) and surface reflectance were measured. The best result of arithmetic mean(wavelength from 400nm to 1000nm) reflectance with acid texturing is 4.64% less than alkali texturing.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.760-763
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• 2012

This study was conducted to investigate foliar treatment effects of organic agricultural materials for the environmentally-friendly cultivation of grape. The organic materials applied were chitosan, wood vinegar (pyroligneous acid), amino acid solution, and ginkgo leaf extract. All the organic materials were relatively strong acidic ranging lower than pH 4.6. when comparing with other organic materials, amino acid solution contained relatively high contents of selected plant nutrients, such as N, P, K, Ca, Mg, Cu, Fe, Mn, and Zn. As comparison of selected soil properties in the grape cultivating field, soil pH values were lower at the harvest stage than at the first stage of grape growing (before treating the organic materials), and electrical conductivity (EC) and soil organic matter content were higher at the harvest stage in the all plots. The concentrations of available phosphorus increased in most of the plot soils except in control plot (conventional treatment). The concentrations of exchangeable K decreased in the plot treated with ginkgo leaf extract and the control plot. The exchangeable Mg concentrations decreased in soils of all the plots. On the other hand, the concentrations of N and K in the grape leaves were higher with the treatments of chitosan and amino acid solution, P concentrations were higher with the applications of chitosan, wood vinegar and amino acid solution, and Ca and Mg concentrations were higher with chitosan and amino acid solution treatments, respectively, than with others. The yields of grape were higher, $1,581{\sim}1,583kg\;10a^{-1}$, in the control and wood vinegar treatment plots than others. Sugar contents of grape were not different among all the plots.

• Resources Recycling
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• v.28 no.6
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• pp.36-45
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• 2019

The spent petroleum catalysts contain rare metals such as vanadium, nickel, molybdenum, and cobalt. Therefore, the leaching of these rare metals from spent petroleum catalysts by organic acid was investigated in the present study. The leaching efficiency of metals by organic acid was in the following order: oxalic acid > tartaric acid > citric acid > maleic acid > ascorbic acid. Among the organic acids employed in this work, oxalic acid can be considered to be superior to the other acids in terms of metals leaching efficiency. The effect of several leaching conditions such as temperature, acid concentration, pulp density, stirring speed, and reaction time on the leaching of metals was investigated. Vanadium and molybdenum were selectively dissolved by oxalic acid from the spent catalysts. The leaching kinetics of vanadium by oxalic acid was also investigated. An activation energy of 8.76 kJ/mol indicated that the leaching kinetics of vanadium by oxalic acid solution was controlled by mass transfer.

• 보존과학연구
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• s.16
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• pp.112-122
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• 1995

TEN-STORIED STONE PAGODA ON THE SITE OFWON-GAKSA(Temple) which is one of three marble pagodas in South Korea, were dated from the thirteenth year of the reign of King Sejo(1467). On the roof and surface of each the stories, there were large amount of the contaminants such as pigeon′s excretions, dust and environmental elements for a long time. The pH of contaminants is not acid, but is 7.2, neutral. To find the species of organic acidscontained in the contaminants and the degree of damaging for a marble pagoda, we analyzed the contaminants using GC-MSD method by the following procedures. Organic acids were extracted by saponifying whole contaminants. After Saponification, the organic acids were mathylated to increase their volatility upon subsequent GC-MSD analysis. The mathyl esters of the organic acids are extracted from the acidified aqueous solution. And the organic extracts were washed with adilute base solution. The washed extract were analyzed by GC(Hewlett Packard 5890)with a nonpolar capillary column(Crosslinked 5% Ph Me Silicone, $50×0.2㎜×0.33\mum$film thickness, USA) and Mass Spectrometric Detector(Hewlett Packard 5970B).As the result, it was found that 12 organic acids were the main compound in pagoda′contaminants, and the amount of organic acid were negligible.