• Carbon letters
• /
• v.5 no.2
• /
• pp.55-61
• /
• 2004

Adsorption isotherms of p-nitrophenol from its aqueous solutions on two samples of activated carbon fibres and two samples of granulated activated carbons have been determined in the concentration range 40~800 mg/L (ppm). The surface of these carbons was modified by oxidation with nitric acid and oxygen gas, and by degassing the carbon surface under vacuum at temperatures of $400^{\circ}C$, $650^{\circ}C$ and $950^{\circ}C$. The oxidation of carbon enhances the amount of carbon-oxygen surface groups, while degassing decreases the amount of these surface groups. The adsorption of p-nitrophenol does not depend upon the surface area alone but appears to be influenced by the presence of oxygen groups on the carbon surface. The adsorption decreases on oxidation while the degassing of the carbon surface enhances the adsorption. The decrease in adsorption depends upon the strength of the oxidative treatment being much larger in case of the oxidation with nitric acid, while the decrease in adsorption on degassing depends upon the temperature of degassing. The results show that while the presence of acidic surface groups which are evolved as $CO_2$ on degassing suppress the adsorption of p-nitrophenol, the presence of non acidic surface groups which are evolved as CO on degassing tend to enhance the adsorption. Suitable mechanisms compatible with the results have been presented.

• Carbon letters
• /
• v.7 no.1
• /
• pp.1-8
• /
• 2006

The activated carbon "C" was obtained by carbonization followed by activation with steam at 40% of burn-off. Oxidized carbons C-N, C-P and C-H were obtained by oxidizing the activated carbon C with concentrated nitric acid, ammonium peroxysulfate and hydrogen peroxide, respectively. The textural properties of the carbons were determined from nitrogen adsorption at 77 K. The acidic surface functional groups were determined by pH titration, base neutralization capacity and electrophoretic mobility measurements. The cation exchange capacities of un-oxidized and oxidized carbons were determined by the removal of Cu(II) and Ni(II) from their aqueous solutions. The surface area and the total pore volume decreased but the pore radius increased by the treatment of activated carbon with oxidizing agents. These changes were more pronounced in case of oxidation with $HNO_3$. The surface pH of un-oxidized carbon was basic whereas those of the oxidized derivative were acidic. The removal of Cu(II) and Ni(II) was pH dependent and the maximum removal of the both ions was obtained at pH of 5-6. Cu(II) was more adsorbed, a phenomenon which was ascribed to its particular electronic configuration.

• Journal of the Korean institute of surface engineering
• /
• v.49 no.3
• /
• pp.231-237
• /
• 2016

This article reports a new chemical bath for preparing a mirror-like surface of AZ31 Mg alloy. In order to find an appropriate chemical polishing solution, four different acidic solutions of sulphuric acid, nitric acid, acetic acid and a specially designed mixture of nitric acid and acetic acid were investigated in view of the changes in surface appearance, roughness and dissolution rate of AZ31 Mg alloy. The surface scales on AZ31 Mg alloy were readily removed by all the acidic solutions, but a reflective surface was produced only by etching in the specially designed solution, and only after a specific etching time. The surface roughness increased with etching time in sulphuric acid, nitric acid, and acetic acid, but it lowered after a specific etching time in the specially designed mixture of nitric acid and acetic acid. Dissolution rate of the alloy in the specially designed mixture of nitric acid and acetic acid appeared to be more than twice than that in separate nitric acid or acetic acid. In this work, we recommend the mirror-like surface of AZ31 Mg alloy obtained by polishing for an optimum time in a mixture of nitric acid and acetic acid for following surface finishings, chemical conversion coating, electroplating, electrophoretic painting and anodizing treatment.

• Journal of Korean Society of Water and Wastewater
• /
• v.24 no.1
• /
• pp.15-24
• /
• 2010

Coagulation can be used for pretreatment of NF membrane filtration. Foulants such as organic matter and particulate can be removed effectively with the process while high flux recovery is maintained. Recently various types of polyaluminium coagulants including polyaluminium chloride(PAC) are commercially available for water treatment. This study examines effects of polymeric Al and hydrolysis products of PAC on nanofiltration membrane performance. Dominant hydrolysis products were polymeric Al, $Al(OH)_3$, and ${Al(OH)_4}^{-1}$ at acidic, neutral, and alkaline pH conditions, respectively. Under acidic pH condition, flux decline was increased with increasing PAC concentrations, possibly due to polymeric Al adsorption on membrane pore and/or surfaces. For neutral and alkaline pH conditions, little flux decline was observed with increasing PAC concentrations except the highest ${Al(OH)_4}^{-1}$ concentration, with which rapid flux decline was shown. Removal of ionic matters was also varied with pH conditions in this study. Especially, conductivity removal was substantially low and $Ca^{2+}$ concentration in the permeate was quite high at neutral pH condition.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.45 no.10
• /
• pp.1518-1524
• /
• 2016

This study was performed to minimize quality degradation of concentrated strawberry puree after $90^{\circ}C$ for 5 min by heat treatment with citric acid (CA) and acidic sodium metaphosphate (ASM) as pH modifiers. The highest color value was 1% CA+1% ASM (13.027), followed by 1% CA (9.539) and control (6.905). Anthocyanin contents were also 1% CA+1% ASM (3.049 mg/100 g), 1% CA (1.140 mg/100 g), and control (0.757 mg/100 g) in sequence. The DPPH radical scavenging activities of control, 1% CA, and 1% CA+1% ASM were 58.148, 72.638, and 83.736%, respectively. The color values, anthocyanin contents, and DPPH radical scavenging activities were significantly different at P<0.05 between control and 1% CA+1% ASM treatment. For the results of overall preference for hedonic test, there was no significant difference at P>0.05 among the three samples. During heat treatment, quality degradation of concentrated strawberry puree was reduced by 1% CA+1% ASM treatment, which is expected for new acidulants.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.34 no.2
• /
• pp.247-254
• /
• 2005

The objective of this study is to compare the chemical properties of red ginseng, white ginseng, and extruded ginseng. Six kinds of samples were prepared and examined their chemical components. The comparison among crude ash, crude lipid, and total sugar resulted insignificant difference. White ginseng had lower content of reducing sugar than those of extruded ginseng and red ginseng. Total amino acid was found relatively low in treatment A (sliced whole root and dried at 7$0^{\circ}C$). Total amino acid of treatment C (extruded dry whole root ginseng slices, moisture content 30%, barrel temperature 11$0^{\circ}C$, and screw speed 200 rpm) was higher than that of treatment B (extruded dry whole root slices, moisture content 25%, barrel temperature 11$0^{\circ}C$, and screw speed 200 rpm). Crude saponin of treatments A, B, C, D (white ginseng with skin), E (skinless white ginseng), and F (red ginseng) were 4.02, 4.77, 4.12, 3.56, 3.25, and 4.02%, respectively. Ginsenoside was contained similarly as crude saponin. The amount of ginsenoside in the treatment of A, B, C, D, E, and F was recorded respectively at 6.031, 8.108, 6.876, 7.978, 5.591, and 9.834 mg/g. A specific component in red ginseng, $R_{g3}$ was detected in treatment F. Maltol was detected in treatment Band F. Acidic polysaccharide was increased 2∼3% by extrusion process. In conclusion, extruded ginseng had similar components to those of red ginseng.

• Korean Journal of Food Science and Technology
• /
• v.48 no.5
• /
• pp.496-501
• /
• 2016

This study was conducted to minimize the quality degradation of concentrated blueberry juice after $90^{\circ}C$ treatment for 5 min by means of citric acid (CA) and acidic sodium metaphosphate (ASM) as pH modifiers. The highest anthocyanin content was observed at 1% CA+1% ASM (65.747 mg per 100 g) followed by 1% CA (46.022 mg per 100 g) and control (30.864 mg per 100 g). The DPPH radical scavenging activities of 1% CA+1% ASM, 1% CA and control were 87.338, 75.486 and 67.983% in respectively. The elastase inhibitory activity at 1% CA+1% ASM, 1% CA and in the control was 87.338, 75.486 and 67.983%, and the tyrosinase inhibitory of these samples were 77.891, 67.598 and 26.375%, respectively. Anthocyanin contents, DPPH radical scavenging, elastase inhibitory and tyrosinase inhibitory activities were significantly different (p<0.05) between the 1% CA+1% ASM treatment and control. During the heat treatment, quality degradation of concentrated blueberry juice was reduced by the 1% CA+1% ASM treatment, as expected for new acidulants.

• Journal of Life Science
• /
• v.29 no.11
• /
• pp.1258-1266
• /
• 2019

Yangkyuksanhwa-Tang (YKSH), consisting of nine different herbs, is commonly used in Soyangin-type individuals with stroke, based on the Sasang Constitution Theory in Korea. However, no evidence has yet confirmed a beneficial effect of YKSH in ischemic stroke treatment. In this study, we investigated the effects of YKSH on ischemic brain injury in a mouse model of cerebral ischemia. Focal cerebral ischemia in mice was induced by photothrombosis, and behavioral recovery was evaluated. Infarct volume, inflammation, and newly generated cells were evaluated by histology and immunochemistry. YKSH treatment resulted in a significant recovery from the motor impairments induced by focal cerebral ischemia, as determined with wire grip and rotarod tests. YKSH treatment also decreased the infarct volume and the number of cells positive for tumor necrosis factor-${\alpha}$ and myeloperoxidase when compared with a vehicle-treated control group. By contrast, YKSH treatment considerably increased the number of cells positive for glial fibrillary acidic protein and ionized calcium-binding adapter molecule 1, as well as the number of cells doubly positive for Ki67/doublecortin when compared with the vehicle-treated group. These results suggest that YKSH treatment attenuated the infarct size by anti-inflammatory action, astrocyte and microglia activation, and neuronal proliferation, thereby facilitating neurofunctional recovery from a cerebral ischemic assault. YKSH could therefore be a potential treatment for neurofunctional restoration of the injured brains of patients with stroke.

• Textile Coloration and Finishing
• /
• v.13 no.5
• /
• pp.1-1
• /
• 2001

As the basic study to investigate the mechanism of improvement in the dyeing fastness of natural dyes on silk fabrics the optical behavior of tannin solution, the optimal condition of tannin treatment and the changes of the physical structure of silk fabrics were studied in the treatment of tannin. Results obtained were as follows ; 1.The K/S values of tannin-treated silk fabrics were not changed by tannin content on silk fabrics but yellowing of tannin in treatment condition. 2. As the concentration of tannin was increased in its treating condition, the tannin content and K/S vague of tannin-treated silk fabrics were increased. 3. Because tannin gave rise to yellowing by hydrolysis and oxidation at high temperature, the higher tannin-treating temperature was, the lower the tannin content and K/S values of silk fabrics 4. The tannin content of silk fabric was higher in acidic treating condition and the highest K/S value was showed at pH 5. 5. As the tannin content of silk fabric was increased, the value of ζ -potential of it became negative. 6. As the tannin content of silk fabric was increased, the crystallinity and crystallite size of it were decreased. This meant that the fraction of amorphous region in the fibers increased. And the degree of orientation of it was decreased with the tannin treatment.

• Textile Coloration and Finishing
• /
• v.13 no.5
• /
• pp.289-297
• /
• 2001

As the basic study to investigate the mechanism of improvement in the dyeing fastness of natural dyes on silk fabrics the optical behavior of tannin solution, the optimal condition of tannin treatment and the changes of the physical structure of silk fabrics were studied in the treatment of tannin. Results obtained were as follows ; 1 The K/S values of tannin-treated silk fabrics were not changed by tannin content on silk fabrics but yellowing of tannin in treatment condition. 2. As the concentration of tannin was increased in its treating condition, the tannin content and K/S vague of tannin-treated silk fabrics were increased. 3. Because tannin gave rise to yellowing by hydrolysis and oxidation at high temperature, the higher tannin-treating temperature was, the lower the tannin content and K/S values of silk fabrics 4. The tannin content of silk fabric was higher in acidic treating condition and the highest K/S value was showed at pH 5. 5. As the tannin content of silk fabric was increased, the value of $\xi$ -potential of it became negative. 6. As the tannin content of silk fabric was increased, the crystallinity and crystallite size of it were decreased. This meant that the fraction of amorphous region in the fibers increased. And the degree of orientation of it was decreased with the tannin treatment.