• Applied Chemistry for Engineering
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• v.24 no.4
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• pp.428-432
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• 2013

From the forest areas in Chungbuk, large amounts of wood wastes by pruning are generated, however most of them considered as by-products are not treated properly with no disposal options. In this work, among diverse wood wastes such as Quercus variabillis, Juniperus chinensis, Larix kaemoferi, and Pinus densiflora, Juniperus chinensis was found to be more effective biosorbent for the removal of lead ions than other wood wastes. Also, the enhancement of lead removal efficiency from the aqueous phase was investigated using Juniperus chinensis waste. It was observed that the optimal initial pH to increase the removal efficiency of 20 mg/L lead ions was 4.0 and the optimal dosage concentration with regard to the biosorbent for the enhanced removal of 50 mg/L lead ions was 0.6 g/100 mL. In addition, chemical treatment of Juniperus chinensis waste with sulfuric acid was required to improve the adsorption capacity for high lead concentrations (over 100 mg/L). When Juniperus chinensis waste was chemically treated with 6 M sulfuric acid, the adsorption quantities of lead ions were 180, 340, and 425 mg/g with regard to 200, 400, and 500 mg/L lead ions concentrations, respectively. These results indicate that the practical biosorbent technology developed in this study is a highly efficient method to treat the lead ion from an aqueous solution.

• Applied Chemistry for Engineering
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• v.23 no.4
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• pp.399-404
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• 2012

The objective of this study was to investigate the efficient pretreatment method for bioethanol production from rice hull. Ammonia and sodium hydroxide as an alkaline solution and dilute sulfuric acid as an acidic solution were used in a batch reactor under high-temperature and high-pressure conditions. The highest enzymatic saccharification efficiency of 82.8% and ash removal rate of 94.7% were obtained in the dilute sulfuric acid treated sample after the sodium hydroxide solution treatment. The enzymatic saccharification efficiencies and ash removals of pretreated rice hull samples have very similar variation tendency. This means that the maximum obstructive factor for the enzymatic saccharification of rice hull is the ash (silicate) content in biomass. The findings suggest that the combined sodium hydroxide-dilute sulfuric acid treatment system under high-temperature and high-pressure conditions is a promising pretreatment method to enhance the enzymatic saccharification of the silica-rich biomass.

• Clean Technology
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• v.19 no.2
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• pp.148-155
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• 2013

Volatile fatty acids (VFAs) production from marine brown algae, Saccharina japonica, was investigated in anaerobic dark fermentation. In order to evaluate the VFAs productivity, various experimental parameters (i.e., physicochemical pre-treatment, microorganism inoculation ratio, substrate concentration, and pH) were evaluated. According to the physicochemical pre-treatment methods, the maximum concentrations of VFAs were obtained in the order of sulfuric acid, subcritical water and subcritical water with lipid-extraction. Also, we investigated the operating parameters such as microorganism inoculation ratio (MV/M = 10 to 30), the substrate concentration (18.0 to 72.0 g/L) and pH (6.0 to 7.0) in sulfuric acid pre-treatment method. When the substrate concentrations were 18.0, 36.0, 54.0 and 72.0 g/L at $35^{\circ}C$, microorganism inoculation ratio 15, pH 7.0 for 372 hours, the maximum concentrations of VFAs were respectively 9.8, 13.9, 18.6 and 22.3 g/L. The change in VFAs concentrations was detected that acetic- and propionic acids increased according to increasing pH, while the butyric acid increased with decreasing pH. The VFAs obtained from concentration and separation process may be used as basic chemistry materials and bio-fuel, and they will expect to produce alternative energy of fossil fuel.

• Journal of Surface Science and Engineering
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• v.57 no.3
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• pp.201-207
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• 2024

This study compared the chemical resistance properties according to various sealing treatment methods for the anode film formed during the anodization process of Al6061 alloy. Al6061 aluminum was used in four different sealing treatment methods: boiling water sealing, lithium sealing, nickel sealing, and pressurized sealing, and each sample was evaluated for corrosion resistance through a 5% HCl bubble test and the microstructure was observed through a scanning electron microscope(SEM). According to the results, corrosion resistance increased as time and temperature increased in all sealing treatment methods. Relatively, corrosion resistance was high in the order of boiling water sealing, lithium sealing, nickel sealing, and pressure sealing, and the best corrosion resistance was found in pressure sealing. These research results can be helpful in selecting a process necessary to improve the efficiency and performance of anodizing process in the industrial field using aluminum alloys.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.4
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• pp.421-426
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• 2008

Freshly harvested seed of Chinese milk vetch (Astragalus sinicus L.; CMV) was strongly dormant because of hardseedness. Seeds of freshly harvested germinated only 8% while clipping the seed coat completely overcome the innate dormancy, which indicates inhibition of germination of the seed is mainly due to seed coat (87%). The dormant (intact) hard seeds did not imbibe water whereas the non-dormant (clipped) seeds took up rapidly. In natural environment condition, the hard seed coat dormancy was broken only after 5 months after seed harvest. To break such a strong seed coat dormancy, the chemical and heat treatments were effective. Concentrated sulfuric acid was more effective than dry heat and hot water treatments. Hot water treatment improved germination but the germination percentage was less than 41%. Treatments increased germination due to its effect on the seed coat integrity. A scanning electron microscope reveled that disruption of seed coat layers and subsequent development of numerous crack in the hilum region of the seed and on the seed coat surface of concentrated sulfuric acid treatment and formation of cracks in the dry heat treatments, respectively, were observed in the seed coat surface, which served as water entry points.

• Journal of environmental and Sanitary engineering
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• v.15 no.2
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• pp.34-40
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• 2000

In the tungsten industry, molybdenum wire which used as the center supporter for coil shape tungsten wire was removed. Nitric acid dissolution method which used prevalently up to the present, takes nitric acid as major component and use noxious material such as sulfuric acid and hydrochloric acid remove molybdenum wire which used as center supporter by dissolve selectively within the range of no damage on tungsten wire. Mixed acid waste water occurred to the process were difficult to be decomposed by the conventional methords. This mixed acid waste water was treated by ozone, and It was obtained using possible by-product through the treatment waste water. For the three reactors with the same volume ; Blank reactor, Disturbance plate reactor, Packed-bed reactor ; the results were as follows : For the blank reactor COD removal efficiency in the pH = 4 (HRT : 6hr) was 28.5%, COD removal efficiency in the pH = 7 (HRT : 6hr) was 28.6%, and COD removal efficiency in the pH = 10 (HRT : 6hr) was 27.8%. For the disturbance plate reactor COD removal efficiency in the pH = 4 (HRT : 6Min.) was 86.5%, COD removal efficiency in the pH =7 (HRT : 6Min.) was 84.4%, and COD removal efficiency in the pH = 10 (HRT : 60Min.) was 86.8%. For the packed-bed reactor COD removal efficiency in the pH = 4 (HRT : 40Min.) was 76.0%, COD removal efficiency in the pH = 7 (HRT : 40Min.) was 81.3%, and COD removal efficiency in the pH = 10 (HRT : 40Min.) was 84.6%. After O3 treatment using possible by-product(Na2SO4) was 150g/ℓ.

• Journal of Soil and Groundwater Environment
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• v.15 no.4
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• pp.13-20
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• 2010

The purpose of this study was to develope the remediation method of contaminated soils with metals and petroleum. The diesel degrading strain was isolated and identified from the soil contaminated by petroleum at industrial sites. Diesel biodegradation experiment was performed by diesel degrading bacteria in both solution and soil slurry. Contaminated soils by Zn or As and diesel were treated consecutively by steam-vapor extraction, biodegradation, and acid washing. The strain was identified as Pseudomonas aeruginosa, and named as Pseudomonas aeruginosa TPH1. The optimal culture conditions of TPH1 were $20^{\circ}C$ and pH 7.0, 3% of diesel concentration. Biodegradation of diesel was performed using the separated strain in liquid medium, and 63% of diesel was degraded in 72 hours. And 52% of diesel was removed in the tested soils. In the treatment of contaminated soils with diesel and Zn or As, 29% ~ 44% of diesel was reduced by steamvapor extraction, 60% ~ 71% of diesel was removed after biodegradation. 47% of Zn and 96% of As were removed after acid(mixture of sulfuric and oxalic acids) washing. It is recommended that consecutive treatment method of steam-vapor extraction, biodegradation and acid washing is effective for remediation of complex contaminated soils with metals and petroleum.

• Corrosion Science and Technology
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• v.11 no.5
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• pp.196-204
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• 2012

Corrosion failure of petrochemical facilities is one of the difficulties in maintenance, since operating conditions of crude oil production, storage, and refinement are very aggressive. UNS N08810, which has been used for crude oil transportation pipes and storage tanks in petrochemical industries, shows good resistance to general corrosion and localized corrosion in several environments. Among its environments, UNS N08810 showed better corrosion resistance in fuel gas containing sulfuric acid and phosphoric acid and sulfur. However, ductility and toughness at high temperature over about $500^{\circ}C$ were greatly reduced due to microstructural change. In general, welding process is the representative method to join the parts in industrial components. Because the alloy by welding can be sensitized and corroded, the manufacturing process should be controlled. In this work, UNS N08810 was used and heat treatment conditions including solution and stabilization treatments were controlled. Oxalic acid etch test by ASTM A262 Practice A was done to evaluate the qualitative sensitization in room temperature. Huey test by ASTM A262 Practice C was done to evaluate the intergranular corrosion rate in boiling 65% $HNO_3$ solution. Also, the microstructure by thermal history was analyzed. Experimental alloy showed high intergranular corrosion rate and its corrosion mechanism was elucidated.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.243-244
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• 2022

Recently, the utilization of carbon nanotubes (CNT) in cement paste has been widely investigated in terms of improving the dispersion quality and enhancing the cement paste mechanical performance. While methods of functionalizing the CNT using surfactants to disperse the nanoparticles have been studied to some extent, the literature on the effects of chemical covalent functionalization is still scarce. This work focuses on chemical functionalization of multiwall carbon nanotubes (MWCNT) using acid treatment, and a consequent addition of the modified MWCNT to the cement paste. The microstructural observation and degree of the MWCNT functionalization are examined using FE-SEM. The compressive strength is measured at an age of 28 days. The results of the study suggest that the acid-functionalized MWCNT are dispersed better compared to the pristine MWCNT due to presence of functional groups. The better dispersion of the nanotubes and the attached functional groups may contribute to the refinement of the microstructure of the cement paste and hence, increase its mechanical strength.

• KSBB Journal
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• v.13 no.1
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• pp.114-118
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• 1998

The effects of fibron solubilization conditions on molecular weight distribution of enzymatically-hydrolyzed silk peptides were investigated. The weight-averaged molecular weights of silk proteins prepared by solubilization with calcium chloride, ethylenediamine and sulfuric acid were 41600, 3308, and 1268 dalton, respectively. Silk peptides in the average molecular weight range of 600-1200 dalton were obtained by protease treatment from solubilized silk fibroin. After the acid hydrolysis of silk protein using hydrochloric acid for 24 hr, silk protein was hydrolyzed to peptides whose average molecular weight and free amino acid content were 145 dalton and 80%, respectively. It was possible to control molecular weight distribution of silk peptides by the combination of solubilization and hydrolysis methods. Among the various treatment methods, acid solubilization followed by protease treatment had an advantage of molecular weight control for the peptide production.