• Journal of Biosystems Engineering
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• v.43 no.1
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• pp.59-71
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• 2018

Purpose: Cellulose nanocrystals (CNCs) are natural polymers that have been promoted as a next generation of new, sustainable materials. CNCs are invaluable as reinforcing materials for composites because they can impart improved mechanical, chemical, and thermal properties and they are biodegradable. The purpose of this review is to provide researchers with information that can assist in the application of CNCs extracted from waste agricultural byproducts (e.g. rice husks, corncobs, pineapple leaves). Methods & Results: This paper presents the unique characteristics of CNCs based on agricultural byproducts, and lists processing methods for manufacturing CNCs from agricultural byproducts. Various mechanical treatments (microfluidization and homogenization) and chemical treatments (alkali treatment, bleaching and hydrolysis) can be performed in order to generate nanocellulose. CNC-based composite properties and various applications are also discussed. Conclusions: CNC-based composites from agricultural byproducts can be combined to meet end-use applications such as sensors, batteries, films, food packaging, and 3D printing by utilizing their properties. The review discusses applications in food engineering, biological engineering, and cellulose-based hydrogels.

• Journal of the Korean Applied Science and Technology
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• v.15 no.4
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• pp.87-93
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• 1998

In spite of various applications of chitin derivatives from waste marine sources, commercial use of chitin has been limited due to resistance to chemicals and the absense of proper solvents. We prepared chitin through decalcification, bleaching and deproteination from protunus trituberculatus shells by the application of Hackman's method. Structural and chemical properties of chitin were investigated to have proper specific surface area and particle size by IR, BET and PSA. The amount of absorbed water of chitin reached equilibrium by stirring about 15 minutes. The amount of absored water of the prepared chitin were large than the commercial chitin. When prepared chitin tested on dyeing wastewater, they showed better treatment efficiency in COD, suspended solid, and color tests than the commercial chitin. The adsorption capacity increased with decreasing particle size for the prepared chitin. Treatment efficiency for color was increased as the sitirring rate increased. Results show the possibility of the prepared chitin from waste marine sources as a treatment system for dyeing wastewater.

• Natural Product Sciences
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• v.24 no.2
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• pp.125-131
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• 2018

Berries and branches essential oil of Juniperus phoenicea were obtained by electromagnetic induction heating assisted extraction and by hydrodistillation with a yield varied from ($1.2{\pm}0.3$ to $2.4{\pm}0.7%$) and from ($0.6{\pm}0.1%$ to $1.1{\pm}0.1%$), respectively. forty eight compounds were identified representing (97.2 - 99.7%) of the oil. ${\alpha}$-Pinene (40.3 - 67.8%) and ${\delta}$-3-carene (13.5 - 26.8%) were the main compounds in berries and branches essential oils. Antioxidant activity was evaluated by three means: inhibition of 2, 2-diphenyl-1-picryl hydrazyl (DPPH) free radical, reducing power and ${\beta}$-Carotene/linoleic acid bleaching. The antioxidant activity of essential oils showed $IC_{50}$ ranging from $67.6{\pm}1.02{\mu}g/mL$ to $131.5{\pm}0.8{\mu}g/mL$ for berries and from $98{\pm}1.25{\mu}g/mL$ to $166.8{\pm}0.29{\mu}g/mL$ for the branches. Berries oil show more potent antioxidant activity compared to branches. This result is supported by the three methods investigated in this work.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.10a
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• pp.160-161
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• 2003

In Korea, 1, 357 tonnes of benzoyl peroxide was produced as a white granule with purities ranging 22 to 95％ in 2001. 75% of benzoyl peroxide is mainly used in the manufacture of expandable styrene polymer and other resins as initiators of polymerization and also been used in the treatment of acne vulgaris and the medical product contains mainly 5 to 10% of it. A very small portion of benzoyl Peroxide is used as flour bleaching agent, Potential human exposure from workplaces is expected to be negligible because this chemical is produced in closed system in only one company in Korea and when a production facility monitors its workplace for the worker exposure annually, the concentration of airborne aerosols at the personal sampling has been less than 1mg/㎥.

• Journal of Powder Materials
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• v.23 no.2
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• pp.102-107
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• 2016

We demonstrate the electrochromic properties of $TiO_2$ nanotubes prepared by an anodization process and investigate the effects of heat treatment and viologen incorporation on them. The morphology and crystal structure of anodized $TiO_2$ nanotubes are investigated by scanning electron microscopy and X-ray diffraction. As-formed $TiO_2$ nanotubes have straight tubular layers with an amorphous structure. As the annealing temperature increases, the anodized $TiO_2$ nanotubes are converted to the anatase and rutile phases with some cracks on the tube surface and irregular morphology. Electrochemical results reveal that amorphous $TiO_2$ nanotubes annealed at $150^{\circ}C$ have the largest oxidation/reduction current, which leads to the best electrochromic performance during the coloring/bleaching process. Viologen-anchored $TiO_2$ nanotubes show superior electrochromic properties compared to pristine $TiO_2$ nanotubes, which indicates that the incorporation of a viologen can be an effective way to enhance the electrochromic properties of $TiO_2$ nanotubes.

• Journal of the Korean Electrochemical Society
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• v.10 no.4
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• pp.235-238
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• 2007

There is great interest in the applicability of generated hydrogen peroxide to a variety of industrial processes, usually involving oxidation of organics. Hydrogen peroxide is now employed for the bleaching as well as mechanical and chemical treatment in the pulp and paper industries. It addition, it is considered as an agent to displace the traditional alkaline treatments with chlorine-based chemicals. This paper reports a comparative study of $H_2O_2$ electogeneration on gas-diffusion electrode in divided cell with several $Nafion^{(R)}$ proton-exchange membranes, Russian cation-exchange membrane MK-40 and SPEEK membrane. The influence of different PEMs on electro-chemical cell voltage, current efficiency and energy consumption of hydrogen peroxide generation has been studied.

• Applied Chemistry for Engineering
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• v.22 no.5
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• pp.579-581
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• 2011

Spectroscopic evaluation of hair chemical damage was performed by SEM/EDS, CLSM, and FT-IR spectroscopy. In SEM/EDS, hydrogen peroxide treated hair showed the loose packing of surface scales, lower ratio of sulfur element and higher ratio of oxygen atom. In the optical single section by using CLSM, high fluorescent intensity appeared in untreated hair. However, in case of treated hair, low fluorescent intensity appeared. This results the aromatic amino acids which can be autofluorescent were more abundant than bleached hair. FT-IR spectra showed that cysteic acid band intensity was increased by performing the bleaching treatments. These results indicate that the oxidative damage cleaves the S-S bond and results in the lower working force of hair fiber.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.05a
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• pp.150-151
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• 2003

Benzoyl peroxide is a high production volume chemical, which was produced about 1,375 tons/year in Korea as of 2001 survey. Most of them are used as initiators in polymerization, catalysts in the plastics industry, bleaching agents for flour and medication for acne vulgaris. The substance is one of the sever chemicals of which human and environmental risks are being assessed by National Institute of Environmental Research under the frame of OECD SIDS Program. It has a melting point of 104-106 $^{\circ}C$ and has solubility of 9.1 mg/1 in water at 25 $^{\circ}C$. The substance was readily biodegradable (83 % after 21days) and had toxic effects to aquatic organisms. The range of 72 hr-EbC50 (biomass) for algae was 0.07-0.44 mg/1 and 48 hr-EC50 for daphnia was 0.07-2.91 mg/1. The LC50 of acute toxicity to fish was 0.24-2.0 mg/1. Although the toxic effects of benzoyl peroxide to aquatic organisms were investigated, environmental monitoring data were not studied. In this study, distribution of the chemical among multimedia environment was estimated using EQC model based on the physical-chemical properties to evaluate the risk of benzoyl peroxide in environment. In level I, II calculation the chemical was distributed to soil (68.3 %) and water (28.7 %). In level III calculation it was primarily distributed to soil (99.9 %) and overall residence time of 3.4 years was estimated. Benzoyl peroxide could be persistent in environment.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.1
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• pp.100-110
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• 2016

Alkaline Peroxide Mechanical Pulping (APMP) of Pinus densiflora harvested from domestic mountains was explored. APMP contributes to various advantages including pulp quality, elimination of the need for a bleaching process, and energy savings. Sequential treatment of impregnation of bleaching chemicals and refining not only overcome the concern of alkaline darkening of wood chips during chemical impregnation, but it also brightens the chips to the desired brightness levels suitable for writing and printing papers. APMP pulping from Pinus densiflora was greatly influenced by the dosage levels of hydrogen peroxide and sodium hydroxide. Alkaline peroxide treatment was carried out by applying one of three levels of hydrogen peroxide (1.5, 3, and 4.5% based on the oven-dried weight of the wood chips) and one of three levels of sodium hydroxide (1.5, 3, and 4.5% based on the oven-dried weight of the wood chips). Other chemicals including a peroxide stabilizers and metal chelation were constantly added for all treatments. Chemical treatment with a liquor-to-wood ration of 9:1 was carried out in a laboratory digestor. Compared to BTMP, APMP pulping displayed outstanding characteristics including the less requirement of refining energy, the better improvement of tensile strength, the more reduction of shives, and the greater increase of pulp brightness. In particular, when 4.5% of hydrogen peroxide with impregnation during 90 minutes was used, the brightness of APMP reached 64.9% ISO. Even though bulk of APMP was decreased with the increase of sodium hydroxide, a better and improved balance could be achieved between optical and strength properties. The spent liquor obtained from the discharge of the impregnation process at the dosage level of 4.5% hydrogen peroxide exhibited an equal level of residual peroxide with BTMP. In conclusion, APMP pulping showed successful results with Pinus densiflora due to its better response to the development of optical and physical properties compared to TMP pulping.

• Journal of the Korean Wood Science and Technology
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• v.46 no.3
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• pp.221-230
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• 2018

The purpose of this study was to evaluate the effect of several chemical treatments to prevent photodegradation of wood veneer by external UV (Ultraviolet) light. Of woods, walnut veneer is selected as a raw material for this study since it is known as a luxurious wood with dark color giving an esthetic effect. Alcohol-benzene, hydrogen peroxide ($H_2O_2$) and sodium hypochlorite (NaClO) solution were used for investigate the effect on color stabilization. Despite the removal of the extractive compounds, which is known as a discoloration component, a significant color change of walnut wood veneer was observed. Meanwhile, the veneers treated by 20 and 30% $H_2O_2$ solution at $75^{\circ}C$ for 1 h also showed the no positive effect of color stability exposed to UV light although they have a bleaching effect on wood veneer. Besides, it was difficult to maintain the original color of walnut veneer due to the elution of the extractive compounds. On the other hands, the veneer treated by NaClO solution indicated the good performance on color stability despite of the intensive UV light test. However, when the concentration exceeds 3%, surface roughness and fiber damage occurred simultaneously. Therefore, the walnut species should be treated with proper concentration when sodium hypochlorite is applied to the veneer.