• Korean Journal of Materials Research
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• v.27 no.10
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• pp.569-575
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• 2017

To improve photocatalytic performance, a $PbS/ZnO/TiO_2$ nanotube catalyst was synthesized, and its surface characteristics and photocatalytic efficiency were investigated. The hybrid photocatalysts were produced by anodic oxidation and successive ionic layer adsorption and reaction(SILAR). The photocatalytic efficiency was evaluated using the dye degradation rate. The $PbS/ZnO/TiO_2$ photocatalyst significantly enhanced the photocatalytic activity for dye degradation, which was ascribed to the synergistic effect of their better absorption of solar light and a decrease in the rate of excited electron-hole recombination.

• Journal of Magnetics
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• v.21 no.1
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• pp.46-50
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• 2016

$Fe_2O_3/TiO_2$ nanocomposite were successfully synthesized by co-precipitation method using $Fe(NO_3)_3{\cdot}9H_2O$ and $Ti(SO_4)_2$ as raw materials. Structural and textural features of the mixed oxide samples were characterized by X-ray diffractometer, field emission scanning electron microscopy and energy-dispersive X-ray. The effects of initial concentration of oxytetracycline (OTC), different competitive ions and organics on the photocatalytic degradation rate of OTC by the $Fe_2O_3/TiO_2$ nanocomposite were analyzed under UV and visible light irradiation. The results indicate that the optimized initial concentration of OTC was 50 mg/L to achieve the best photocatalytic efficiency. $Cu^{2+}$, $NH_4{^+}$, $C_3H_8O$ and EDTA in the aqueous suspension were found to suppress the degradation rate of OTC, whereas the effect of $NO_3{^-}$ and $H_2C_2O_4$ can be ignored.

• Journal of the Korean Applied Science and Technology
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• v.25 no.1
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• pp.32-40
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• 2008

1,4-Dioxane is an EPA priority pollutant often found in contaminated ground waters and industrial effluents. Conventional water treatment techniques are limited to decompose this compound effectively. Therefore, an advanced oxidation process system (AOP) was used for the degradation of 1,4-dioxane. This research investigates the effect of adding oxidants, such as ozone, air, and $H_2O_2$ during the UV irradiation of 1,4-dioxane solution. In order to analyze 1,4-dioxane, a modified 8270 method, which is an improved method of U.S EPA 8720, was used. Degradation efficiencies of 1,4-dioxane by only UV irradiation at various temperatures were not significant. However, The addition of oxidants and air bubbling in the UV irradiation system for 1,4-dioxane decomposition showed the higher 1,4-dioxane degradation rate. And, during AOP treatment the tendency of TOC changes was similar to that of 1,4-dioxane decomposition rate.

• Journal of Environmental Science International
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• v.22 no.7
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• pp.915-923
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• 2013

Decomposition of non-biodegradable contaminants such as phenol contained in water was investigated using a dielectric barrier discharge (DBD) plasma reactor in the aqueous solutions with continuous oxygen bubbling. Effects of various parameters on the removal of phenol in aqueous solution with high-voltage streamer discharge plasma are studied. In order to choose plasma gas, gas of three types (argon, air, oxygen) were investigated. After the selection of gas, effects of 1st voltage (80 ~ 220 V), oxygen flow rate (2 ~ 7 L/min), pH (3 ~ 11), and initial phenol concentration (12.5 ~ 100.0 mg/L) on phenol degradation and change of $UV_{254}$ absorbance were investigated. Absorbance of $UV_{254}$ can be used as an indirect indicator of phenol degradation and the generation and disappearance of the non-biodegradable organic compounds. Removal of phenol and COD were found to follow pseudo first-order kinetics. The removal rate constants for phenol and COD of phenol were $5.204{\times}10^{-1}min^{-1}$ and $3.26{\times}10^{-2}min^{-1}$, respectively.

• Structural Engineering and Mechanics
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• v.76 no.4
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• pp.541-550
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• 2020

As a new type of concrete material, basic magnesium sulfate cement concrete (BMSC) has the advantages, such as early strength, high strength, good toughness and crack resistance. However, it is unclear about the degradation of the mechanical properties of BMSC columns, which is exposed to the natural environment for several years. In order to apply this new concrete to practical engineering, six large-eccentricity compressive columns of BMSC were studied. The mechanical properties such as the crack propagation, failure morphology, lateral displacement and bearing capacity of BMSC column were studied. The results show that the degradation rate of ultimate load of BMSC column is from 6% to 7%. The degradation rate of the stiffness of the column is from 6% to 13%. With the increase of compressive strength of BMSC, the axial displacement and lateral displacement are gradually reduced. The calculation model of bearing capacity of the BMSC column under the large eccentric compression is proposed. This paper provides a reference for the application of BMSC columns in the civil engineering.

• New & Renewable Energy
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• v.16 no.4
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• pp.83-91
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• 2020

In this study, the reusability of the Fenton oxidation solution was evaluated to reduce the cost of the pretreatment process. Biomass was sequential subjected to Fenton oxidation-hydrothermal treatment and enzymatic hydrolysis to produce monosaccharides. The liquid solution recovered after Fenton oxidation contained OH radicals with a concentration of 0.11 mol/L. This liquid solution was reused for a new Fenton oxidation reaction. After Fenton oxidation, hydrothermal treatment was performed under the same conditions as before, and 9.34-13.63 g/L of xylose was detected. This concentration was slightly lower than that of a fresh Fenton oxidation solution (16.51 g/L) but was higher than that obtained by hydrothermal treatment without Fenton oxidation (2.72 g/L). The degradation rate during hydrothermal pretreatment involving Fenton oxidation was 36.02%, which decreased (29.24-31.05%) slightly when the liquid solution recovered after Fenton oxidation was reused. However, the degradation rate increased compared to that measured from hydrothermal treatment without Fenton oxidation (15.21%). Moreover, the yield after enzyme hydrolysis decreased in the following order: fresh Fenton oxidation-hydrothermal treatment (89.64%) > Fenton oxidation with reused solution-hydrothermal treatment (74.84%) > hydrothermal treatment without Fenton oxidation (32.05%).

• Korean Journal of Agricultural Science
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• v.49 no.4
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• pp.995-1001
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• 2022

The purpose of this study was to compare the effect of solid-state fermentation on soybean using three microbial strains under four different fermentation times. Soybean was fermented for 12, 24, 36 or 48 hours with highly proteolytic microbes, either Bacillus amyloliquefaciens (BA), B. subtilis (BS), or B. subtilis var. natto (BN), and levels of total protein concentration, protein distribution, and antioxidant activity were analyzed. Total protein was highest in the BS 12 h group (9.21 ㎍·µL^-1) and lowest in BN 48 h (6.80 ㎍·µL^-1), respectively (p < 0.001). Furthermore, three microbes decomposed large molecular weight proteins as well as major allergens of soybean such as β-conglycinin, Gly m Bd 30K, and glycinin. Each treatment group showed the highest degradation rate at 48 h fermentation and among the three microbes, BS showed a relatively higher degradation rate. The radical scavenging ability, known as an indicator of antioxidant activity, showed a significant increase in all treatment groups except BA 24 h. The results from this study suggest that protein concentration, and degradation and antioxidant activity were affected by different types of microbial trains and fermentation period and that B. subtilis fermentation might be the most effective way to increase nutritional and functional properties of soybean.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.7 s.144
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• pp.1027-1036
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• 2005

Based on the correlation analysis result of preceding research, the biodegradabilities of cellulose fibers were closely related to the moisture regain of the samples, which reflects the hydrophilicity and internal structure of the fibers. In addition to this factor, it was expected that the biodegradation conditions influence the biodegradability of fibers. In this study, widely used cellulose fibers including cotton, rayon, and acetate were used. The biodegradabilities of cellulose fibers were measured by soilburial test, and then the degradation behaviors based on each condition were compared. Moreover, the effects of degradation conditions such as humidity of the soil were investigated. Changes in the internal structure of samples were also observed by X-ray analysis according to the soil burial time. It was shown that humidity of soil facilitated the degradation of cotton, rayon, and acetate fibers, showing higher degradation rate with higher humidity in soil. This effect was shown to be much greater in the fibers of high moisture regain such as cotton and rayon. In respect of microstructure change, crystallinities and their crystal size of fibers decreased remarkably in the soil of higher humidity. It was revealed that degradation of crystalline area was more dependent on the soil humidity than that of amorphous area.

• Journal of Environmental Science International
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• v.11 no.6
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• pp.597-603
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• 2002

Photocatalytic degradation of phenol was carried out with UV-illuminated TiO$_2$-SiO$_2$ in aqueous suspension. TiO$_2$-SiO$_2$ catalysts were prepared by sol-gel method from the titanium isopropoxide and tetraethylorthosilicate at different Ti/Si ratio and some commercial TiO$_2$ catalysts were used as purchased. All catalysts were characterized by X-ray Diffraction(XRD) and BET surface area analyzer. The effect of reaction conditions, such as initial concentration of phenol, reaction temperature and catalyst weight on the photocatalytic activity was studied. In addition, TiO$_2$-SiO$_2$(49: 1) prepared by sol-gel method showed higher activity than commercial TiO$_2$catalysts on the photocatalytic degradation of phenol. The addition of SiO$_2$ into TiO$_2$hepled to increase the thermal stability of titania which suppressed the formation of anatase into rutile. The photocatalytic degradation of phenol showed pseudo-1st order reaction and the degradation rate increases with decreasing initial phenol concentration.

• Journal of Food Hygiene and Safety
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• v.12 no.4
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• pp.310-314
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• 1997

Antithiamin activities of BHA, BHT, PG and TBHQ of synthetic antioxidants on the effect of temperature and pH was determined by means of HPLC. The influence of synthetic antioxidants on the degration of thiamin was found to be dependent on temperature and pH. The degradation of thiamin was considerably more rapid at pH 7 than pH 4. The influence on the heat of synthetic antioxidants at pH 4 and 38* was extremely slight, but the degradation of thiamin at pH 7 was much more rapid at 60* than at 38*. After 24 hours of incubation both PG and TBHQ at pH 7 and 60* nearly completely destroyed thiamin. Tests of antithiamin activities showed that TBHQ, which was decomposed completely in 72 hours, was more effective than PG at pH 7 and 38* but BHA and BHT hardly had antithiamin activities which was evaluated under various reactions of pH and temperature. Thiamin degradation, at pH 7 and 6$0^{\circ}C$, was proportional to the concentration of PG. When the ratio of PG to thiamin was increased from 0.15:1 to 2:1, the degradation rate also increased. However, the change between ratio of 1:1 and 2:1 was negligible.