• Journal of the Korean Chemical Society
• /
• v.43 no.5
• /
• pp.589-592
• /
• 1999

• Proceedings of the Korean Institute of Industrial Safety Conference
• /
• 2003.10a
• /
• pp.44-47
• /
• 2003

중소규모 사업장의 대부분은 회분식 반응공정을 이용하여 소량 다품종의 제품을 생산한다. 회분식 공정은 연속식 공정에 비해 수동운전의 비율이 높아서 인적오류에 의한 사고발생 가능성이 상대적으로 높으며, 사고 발생 시 인적 피해가 크게 나타날 수 있는 가능성을 내포하고 있다. 또한 대규모의 사업장에 비해 적절한 위험성평가나 안전관리가 이루어지기 어렵다. 따라서 회분식 공정에서의 위험특성을 구체적으로 규명하고, 이를 바탕으로 회분식 반응기에서의 사고를 예방하기 위한 일반적인 가이드를 제시하고자 한다. 이러한 회분식 공정의 위험성평가와 관련하여 영국 및 미국 화공학회에서는 화학반응 및 회분식 반응공정의 위험성평가 지침을 제시하고 있다.(중략)

• Journal of the Korean Chemical Society
• /
• v.53 no.3
• /
• pp.368-376
• /
• 2009

In this study we investigated and tried to understand problems monitored in an experiment on reactivity of metals in chemistry I. Three problems were discussed. First, the reason that aluminium plate does not react with other metal ions such as zinc, iron and copper was studied and the way to overcome this problem was suggested. Second, the reason that the bubbles were generated when FeS$O_4$(aq) and Zn(s) react was discussed. Third, the precipitates which appeared in the reaction of FeS$O_4$(aq) and Zn(s) were identified. Through reference study and experimental investigation, we could reach the following results. First, aluminium could not react with other metal ions due to the surface oxide layer that is formed very fast and prevents aluminium from reacting with metal ions in solution. This problem could be overcome by allowing a competing reaction of acid and aluminium during the reaction of aluminium and metal ions. Second, the observed bubbles were identified to be hydrogen gas, produced by the reaction between metals and hydronium ion in the solution. Third, black precipitates that were produced on the surface of zinc plate and exhibited magnetic property were characterized to be $Fe_3O_4$(s), and brown precipitates that were produced in the solution phase were to be $Fe_2O_3$(s) by the analysis of X-ray photoelectron spectra.

• Prospectives of Industrial Chemistry
• /
• v.24 no.2
• /
• pp.22-30
• /
• 2021

현재 인류는 플라스틱(plastic) 세상에 살고 있다. 의류, 식품, 주거 생활 곳곳에 플라스틱이 존재하며, 플라스틱이 없는 세상은 상상조차 할 수 없다. 하지만, 플라스틱 사용량 증가에 따른 폐플라스틱의 배출량의 증가는 심각한 환경문제들을 야기하여 생태계뿐만 아니라 인간에게도 위협이 되고 있다. 이를 해결하기 위한 방법으로 단순히 폐플라스틱의 처리에 그치지 않고, 이를 활용하여 새로운 고부가가치의 생성물을 제조하는 플라스틱 업사이클링(plastic upcycling) 시스템이 최근 주목을 받고 있으며, 현재 다양한 형태로 연구개발이 진행되고 있다. 그 중의 한가지로 본 기고문에서는 알칸 교차 복분해(cross alkane metathesis) 반응을 소개한다. 알칸 교차 복분해 반응은 수소화/탈수소화(hydrogenation/dehydrogenation) 반응과 올레핀 복분해(olefin metathesis) 반응으로 이루어져, 탈수소화 반응 후 생성된 이중결합 탄소를 갖는 두 개의 알켄 화합물이 자리바꿈을 통해 새로운 이중 결합을 형성하는 반응이다. 이 촉매반응 과정이 반복되면 저분자화된 새로운 알칸 화합물을 생성되는데, 이는 기존의 플라스틱 처리방식인 열분해 및 촉매 분해 공정보다 낮은 반응온도를 요구한다. 또한 이를 통해 상대적으로 높은 순도의 가솔린 및 디젤을 생성할 수 있기 때문에 폐플라스틱 처리 공정의 새로운 대안기술이 될 수 있다. 본 기고문에서 폐플라스틱 중 가장 큰 비중을 차지하는 폴리에틸렌을 처리하는 대안기술로써 알칸 교차 복분해 반응의 메커니즘과 및 촉매의 역할, 그리고 반응성에 영향을 주는 인자에 대해 기술한다.

• Applied Chemistry for Engineering
• /
• v.21 no.4
• /
• pp.385-390
• /
• 2010

Transesterifications of vegetable oils (soybean oil, grapeseed oil, corn oil, canola oil) by ultrasonic energy were examined on various catalysts for biodiesel production. Reaction activities of the transesterifications were evaluated to the ultrasonic energy and thermal energy. The physicochemical properties and product distribution were also investigated to the biodiesels produced from the oils in the reaction using ultrasonic energy. The yields of fatty acid methyl ester (FAME) on the alkali catalysts were higher than those on the acid catalysts. The highest FAME yield was obtained as 83% on potassium hydroxide catalyst in the transesterification. The effective reaction conditions by ultrasonic energy were 1 wt% catalyst loading and 6:1 molar ratio of methanol to vegetable oils. The reaction rate of the transesterification by ultrasonic energy was faster than that by thermal energy. The acid values of the biodiesel products were improved above 30% compared to those of the feedstocks.

• Journal of the Korean Chemical Society
• /
• v.29 no.3
• /
• pp.287-294
• /
• 1985

Acrylamide, N-alkyl substituted acrylamides and N,N-diethylacrylamide were reacted with aryl bromides in the presence of triethylamine and palladium acetate-triorthotolyl phosphine catalyst to form the various substituted aryl conjugated enamides. These reactions proceeded selectively and (E)-isomer of aryl conjugated enamides was obtained. N-alkyl substituted acrylamides were more reactive than acrylamide or N,N-diethylacrylamide and gave high yields of vinylated products. Aryl bromides with electron withdrawing group showed good reactivity but aryl bromides with electron donating group showed poor reactivity or no reactivity for acrylamide or N,N-diethylacrylamide.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.5 no.4
• /
• pp.273-281
• /
• 2007

Hyperalkaline groundwater formed by groundwater-cement components and its reaction with bedrock in a nuclear waste repository were simulated by geochemical modeling. The result of groundwater-cement components reaction showed that the pH of water was 13.3 and the precipitated minerals were Brucite, Katoite, Calcium Silicate Hydrate(CSH1.1), Ettringite, Hematite, and Portlandite. The result of interaction between such minerals and groundwater sampled in Gyeongju area also showed that the pH of groundwater reached 12.4. Interaction between such hyperalkaline groundwater and granite was simulated by kinetic model during $10^3$ years. This result showed that the final pH of groundwater reached 11.2 and the variation of pH was controlled by dissolution/precipitation of silicate and CSH minerals. Groundwater quality was also determined by dissolution/precipitation of silicate, CSH, oxide minerals. Our results show that geochemical modeling of long-term hyperalkaline groundwater and rock interaction can contribute to the safety assessment of engineered barrier by predicting geochemical condition in repository site.

• Journal of the Korean Chemical Society
• /
• v.35 no.2
• /
• pp.158-164
• /
• 1991

The reduction mechanism at a mercury electrode of o-cresolphthalexon(OCP) in strongly alkaline supporting electrolytes has been investigated by several electrochemical techniques. The radical formed after first one electron reduction uptake, dimerizes. The result of cyclic voltammetric investigation demonstrated the reversible nature of the electron transfer and standard rate constant was $3.27{\times}10^{-2}$ cm/sec. The apparent irreversible behavior of the second wave is a result of the existence of a fast protonation following the second electron transfer. At low concentration of OCP(< $1{\times}10^{-4}$M), cathodic current were remarkably adsorptive properties. Prolonged electrolysis was carried out at controlled potential of -1.85V, original violet color of the solution becames progressively weaker, and then colorless solution. The final product of an exhaustive electrolysis is electro-inactive. The appearence of four steps may be explained by the fact that the reduction of OCP elucidated ECEC mechanism.

• The tire
• /
• s.5
• /
• pp.17-22
• /
• 1967

• Journal of the Korean Chemical Society
• /
• v.38 no.6
• /
• pp.465-468
• /
• 1994