• Journal of Soil and Groundwater Environment
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• v.14 no.2
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• pp.26-32
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• 2009

In this study, the degradation of BTEX (benzene, toluene, ethylbenzene, xylene) was tested in both (Fe$^{3+}$+chelating agent)/H$_2$O$_2$system [Fe(III) 1 mM, oxalate 6 mM, H$_2$O$_2$ 3%, and pH 6] and UV/(Fe3++ chelating agent)lHzOz system [UV dose 17.4 kWhlL, Fe(III) 1mM, oxalate 6 mM,H$_2$O$_2$ 1%, and pH 6]. The types of chelating agents used in experiments were catechol, NTA, gallic, acetyl acetone, succinic, acetate, EDTA, citrate, malonate, and oxalate and the optimum chelating agent for BTEX degradation was determined. The results showed that acetate was the optimum chelating agent for BTEX degradation in both (Fe$^{3+}$+chelating agent)/H$_2$O$_2$ and UV/(Fe$^{3+}$+chelating agent)/H$_2$O$_2$ system, and UV radiation enhanced the degradation of BTEX with any types of chelating agents. Moreover, UV/(Fe$^{3+}$+chelating agent)/H$_2$O$_2$ system, which chelating agent was acetate, removed effectively mixtures of BTEX and MTBE (methyl tert-butyl ether) when the concentration of both BTEX and MTBE was 200 mg/L, respectively. In this system, BTEX was degraded completely and 85% of MTBE was degraded at the reaction time of 180 min. Therefore, UV/((Fe$^{3+}$+chelating agent)/H$_2$O$_2$ system with acetate as a chelating agent removed not only BTEX but also BTEX and MTBE, effectively.

• Journal of the Korean Chemical Society
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• v.50 no.6
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• pp.454-463
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• 2006

refractory organic compounds in aqueous solution are not readily removed by the existing conventional wastewater treatment process. In recent years, the sonolysis and electrochemical oxidation process had been shown to be promising for wastewater treatment due to the effectiveness and easiness in operation. This study was performed to investigate the characteristics of sonolytic and electrolytic decomposition as the basic data for development of the wastewater treatment process. Trichloroethylene(TCE) and 2,4- dichlorophenol(2,4-DCP) were used as the samples, and their destruction efficiency were measured with various operating parameters, such as initial solution concentration, initial solution pH, reaction temperature, sonic power and current density. Also, the decomposition mechanism conformed indirectly with the effect of NaHCO3 as a radical scavenger on the decomposition reaction. Thermal decompositon reaction is predominant for TCE but thermal and radical decompositon reactions were dominant for 2,4-DCP. Results showed that the destruction efficiencies of all samples were above 65% within 120 minutes by sonolysis and electrolysis at the same time, and were increased with increasing initial concentration, sonic power and current density. Destruction efficiency of TCE was high in the acidic solution, but 2,4-DCP showed high destruction efficiency in basic solution.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1997.11a
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• pp.313-317
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• 1997

졸-겔법은 액상에서 가수분해에 의해 졸의 겔화 과정을 거쳐 목적하는 산화물을 제조하는 방법이다. 이 방법에 의한 코팅기법은 금속의 부식억제와 세라믹 및 반도체의 박막코팅공정에 중요하게 이용되고 있을 뿐만 아니라 최근에는 방음벽이나 산업안전경 재료인 프라스틱 소재에 표면 경도를 높여 안전성과 내구성이 보강된 복합재료를 만드는데 광범위하게 연구가 진행되고 있다. (중략)

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1997.05a
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• pp.59-65
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• 1997

졸-겔법에 의한 코팅기법은 금속의 부식억제와 세라믹 및 반도체의 박막코팅 공정에 중요하게 이용되고 있을 뿐만 아니라 최근에는 프라스틱과 같은 약한 소재에 표면 경도를 높여 안전성과 내구성이 보강된 복합재료를 만드는데 광범위하게 연구가 진행되고 있다. 졸-겔법은 액상에서 가수분해에 의해 졸의 겔화 과정을 거쳐 목적하는 산화물을 제조하는 방법이다. (중략)

• Resources Recycling
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• v.17 no.5
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• pp.66-75
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• 2008

Using a pinus koraiensis and pinus rigida which are normally being discarded in South Korea, the optimal condition of producing charcoals has been studied to develop activated carbons which can be recycled as a higher value-added product. A study on manufacture of activated carbons from a discarded timber consists of two processes, the production process of charcoals from a discarded timber by low temperature pyrolysis process and the production process of activated carbons from the charcoals by chemical activation reaction. This study deals with the production process of charcoals from a discarded timber by low temperature pyrolysis process. As a results of experiment, it was investigated that charcoals produced through drying at $150^{\circ}C$ for 6hr and pyrolysis process at $500^{\circ}C$ for 1hr had the highest values in physical properties such as iodine number and BET surface area. Furthermore, through observing SEM images, the maximum development of porosity had been founded in this condition. It was confirmed that values of physical properties on using a pinus koraiensis are superior to the ones when using a pinus rigida. When charcoals were produced from a pinus koraiensis in this condition, BET surface area was approx. $640m^2/g$.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.635-638
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• 1999

The effect of proteolytic enzyme on the unhairing process has been studied. this enzyme significantly changed the physical properties of pelt for leather shoes. A SEM was used to examine physical properties of the pelt. Even though bio-tech treatment using proteolytic enzyme slightly reduced the degree of unhairing compared to chemical treatment. Physical property of the pelt is better and this method is environmentally favorable. $H_{2}S$ gas produced in the chemical treatment was not detected and the value of COD and BOD for waste water after the unhairing process were reduced to 939 mg/L and 5268 mg/L, respectively. We found that a process with 0.4~0.5% proteolytic enzyme for 20 h at $29{\sim}30^{\circ}C$ is most suitable for the unhairing process.

• Resources Recycling
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• v.16 no.3 s.77
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• pp.3-11
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• 2007

Presently, most of gold is smelted from gold concentrates and anode slimes. Anode slimes are by-products of nonferrous smelters such as lead and copper. In addition, gold is recovered from waste dental and medical materials, waste gold coating solution, and waste printed circuit boards (waste PCBs). The smelting method of gold from gold concentrates and various wastes containing high concentration of gold is largely divided into chlorination, cyanidation, and amalgamation methods. For the anode slimes, electrolysis method is usually used, which largely consists of roasting, high temperature melting and electrolysis processes. Also, various wastes containing low concentration of gold are mainly treated by pyrometallursical processes. In the paper, current status on gold smelting technology is reviewed, and a novel process for gold smelting which is researched in the recent is briefly introduced.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.7
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• pp.412-417
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• 2017

Removal characteristics of methyl orange and their dependence on operating parameters in a catalytic ozonation were investigated through a series of batch experiments. Activated carbon enhanced the self-decomposition of ozone, generating $OH{\cdot}$, thus promoting methyl orange degradation. As the carbon dose increases, the pseudo-first order rate constants of methyl orange degradation increased, resulting in the fast removal of methyl orange. The increase of gaseous ozone concentration enhanced the mass transfer to the aqueous solution, therefore, promoted the methyl orange removal. The methyl orange degradation was not significantly affected by the change of pH in the range of 5~12, and TOC removal was negligibly affected by the variation of pH over 7. The results indicate that the catalytic ozonation can be considered as an effective dye treatment technology.

• Applied Chemistry for Engineering
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• v.28 no.2
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• pp.171-176
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• 2017

The nitrogen plasma thermal decomposition and recovery processes for $CHClF_2$ (Chlorodifluoromethane) refringent were investigated. The steam generator was employed to provide superheated steam reactor, supporting the decomposition reaction of refringent. Even though over 94% of R-22 was decomposed on the condition of 60 A and 9.0 kW, a higher power and specific energy density were required to achieve the complete combustion of carbon materials. In the operating condition of 60 A and 12.6 kW, $O_2$/R-22 ratio in reactants gases are a key factor to obtain much higher decomposition ratio during process. It should be noticed that injecting the mixture of $O_2$ and air was much more effective than injecting the air consisting equivalent $O_2$ amount.

• Environmental engineer
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• s.127
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• pp.20-24
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• 1997