Earticle

In this study, when Butyl ether, a type of diether-based oxygenated fuel, is mixed in each volume ratio in a naturally aspirated direct injection diesel engine, the exhaust gas emission characteristics of the oxygenated component in the fuel affect each operating area of the engine I wanted to investigate the effect on. For comparative measurement of engine performance and exhaust emissions, commercial diesel and butyl ether mixed fuels were classified into 4 types according to the mixing ratio and tested. As the content of butyl ether in fuel increases, soot emission reduction increases, and when the maximum mixing amount of butyl ether (diesel 80vol-% + BE 20vol%) is applied, compared to the case of using only diesel as fuel, at 2500 rpm and no load, 39%, and about 32% of smoke reduction effect at full load was confirmed.

In this study, when Butyl ether, a type of diether-based oxygenated fuel, is mixed in each volume ratio in a naturally aspirated direct injection diesel engine, the exhaust gas emission characteristics of the oxygenated component in the fuel affect each operating area of the engine I wanted to investigate the effect on. For comparative measurement of engine performance and exhaust emissions, commercial diesel and butyl ether mixed fuels were classified into 4 types according to the mixing ratio and tested. As the content of butyl ether in fuel increases, soot emission reduction increases, and when the maximum mixing amount of butyl ether (diesel 80vol-% + BE 20vol%) is applied, compared to the case of using only diesel as fuel, at 2500 rpm and no load, 39%, and about 32% of smoke reduction effect at full load was confirmed.

Toxic effect of methyl tert-butyl ether (MTBE), tert-butyl alcohol (TBA) and formaldehyde (FA) on microbial activity and diversity was compared in rice field, leek patch, and tidal mud flat soil samples. MTBE, TBA and FA with different concentrations were added into microcosms containing these soil samples, and placed at room temperature for 30 days. Then the microbial activities such as dehydrogenase and viable cell numbers and microbial community using a DGGE (Denaturing gradient gel electrophoresis) fingerprinting method were measured. Among the samples, dehydrogenase activity in rice field was inhibited the most by MTBE, TBA and FA. The toxic effect was higher according to the following orders: FA > MTBE > TBA. Dominant species in the microcosms contaminated with MTBE, TBA and FA were Chloroflex, Bacilli, gamma-proteobacteria in the rice field sample, Sphingobacteria, Flavobacteria, Actinobacteria, Bacilli, gamma-proteobacteria in the leek patch sample, and Sphingobacteria, Flavobacteria, delta-proteobacteria, gamma-proteobacteria in the tidal mud flat sample.

The treatment of soils and water contaminated with MTBE using the Fenton oxidation was investigated. The effects of dosage of $H_{2}O_{2}$, and Fe$^{2+}$ concentrations, and solution pH on transformation and mineralization in soil were evaluated. Generation of TBA and acetone following Fenton-oxidation of MTBE in water and generation of acetone following Fenton-oxidation of TBA were observed. Therefore TBA and acetone are degradation intermediates of MTBE. There was a large difference of treatment efficiency in Fenton oxidation of MTBE between soil and water system. This may be caused by the complex nature of soil, soil organic matter which can consumed OH $\cdot$ radicals, and interacting with inorganic-soil constituents. The pH of soil was observed to have a significant effect on the chemical oxidation efficient of MTBE in soil The data demonstrated that optimal pH range were pH 3~4 and around 6. The soil batch studies demonstrated that treatment efficiency of MTBE was enhanced by adding additional ferrous salts but Fenton-oxidation occurred in no additional iron which indicated that iron in soil can catalyze the Fenton-oxidation. The most effective parameter of Fentonoxidation was $H_{2}O_{2}$/Fe$^{2+}$ ratio which theocratical ratio is 0.5. The optimal range of this ratio was found to be 0.6~2.3. In evaluating effect of $H_{2}O_{2}$ dosage on treatment efficiency, the increase of $H_{2}O_{2}$ did not always lead to increase of decompositions of MTBE in soil. Fenton oxidation was effective in destroying MTBE in aqueous extracts of contaminated soil and water. Experimental data provided evidence that the Fenton oxidation can effectively remediate MTBE-contaminated water and soil.

최근 전 세계적 화두는 친환경 분리공정으로의 전환 및 최적화로 이는 에너지 절감과 환경오염을 줄이는 장점이 존재한다. 이온성 액체(ionic liquids, ILs)는 독특한 성질로 인해 전기화학, 화학공학 재료 및 금속공학 등 여러 분야에서 사용되는 유기용매를 대체할 수 있고, 재활용이 용이하여 대표적인 지속 가능형 물질로 일컬어진다. 고온에서도 증기압이 거의 0에 가까워 흡입되거나 스모그를 형성하지 않고, 독성물질의 대기 중 방출이 적어 자연 친화적이므로 green chemistry의 출발 물질이 된다. 그러나 현재까지 ILs에 대한 공정설계 자료에 대한 연구는 진행되고 있으나 정확한 상평형 및 혼합 물성 자료들이 미흡한 상태이다. 따라서 본 연구는 혼합물의 체계적인 물성 연구의 일환으로 {methyl tert-Butyl Ether (MTBE) + tri-hexyltetradecylphosphonium chloride} 그리고 {MTBE + tri-hexyltetradecylphosphonium bis(2,2,4-trimethylpentyl) phosphinate} 이성분계의 298.15 K에서 과잉 몰부피 및 몰굴절도 편차를 측정하였다. 측정된 이성분계 과잉 혼합 물성은 Redlich-Kister 다항식을 이용하여 상관시켜 보았다.

In recent years, there has been a growing interest in green technologies, leading to the development of a new class of highly tunable substances known as ionic liquids (ILs). For the design and optimization of industrial processes that involve ILs or their mixtures, reliable data on thermodynamic and transport properties is crucial. This information must be accurately represented by predictive models. Therefore, acquiring new experimental data on phase behavior and mixture properties is of significant importance. In this study, we measured excess molar volumes and deviations in molar refractivity for two binary systems: {methyl tert-butyl ether (MTBE) + trihexyltetradecylphosphonium chloride}, and {MTBE + trihexyltetradecylphosphonium bis(2,2,4-trimethylpentyl)phosphinate} at a temperature of 298.15 K. We conducted density and refractive index measurements using a digital vibrating-tube densimeter and a precision digital refractometer, respectively. The experimental data were analyzed and correlated using the Redlich-Kister polynomial.

최근 친환경 분리 공정으로 전환 및 최적화는 세계적으로 화두인 환경오염을 획기적으로 저감하고 막대한 에너지를 절감할 수 있는 지름길이 된다. Ionic liquids (ILs)는 매우 고온에서도 증기압이 거의 0에 가까워 인체에 흡입되거나 스모그를 형성하지 않고, 독성물질의 대기 중 매우 방출이 적어 자연 친화적이므로 green chemistry 물질로 관심을 받고 있다. 특히, ILs는 공비 혼합물 중 특정 성분과 강한 화학적 작용으로 공비점 이동을 유발하는 첨가제로 사용이 가능하다. 그러나 ILs에 대한 공정설계 자료에 대한 연구는 진행되고 있으나 정확한 상평형 및 혼합 물성 자료들이 아직 미흡한 상태이다. 따라서 본 연구는 공비 혼합물인 {methyl tert-butyl ether (MTBE) + methanol}의 공비점 이동 및 제거를 알아보기 위해 phosphonium 계열 ILs 이용하여 {MTBE + methanol + trihexyltetradecylphosphonium chloride} 그리고 {MTBE + methanol + trihexyltetradecylphosphonium bis(2,2,4-trimethylpentyl)phosphinate} 삼성분계 기액평형을 313.15 K에서 headspace gas chromatography을 이용하여 측정하였다. 실험에 측정된 값들은 활동도 계수 모델인 Wilson 식으로 매개변수를 계산하여 비교하였다.

Ionic liquids (ILs) have being gaining more attention recently in the chemical industry and among scientists and chemical engineers because of their many fascinating properties as solvents. ILs can be used as additives for azeotropic distillation in cases where the ionic liquids interact more strongly with a certain component in an azeotropic mixture, thus causing a shift in the azeotropic point. This study demonstrates the influence of ILs on shifting the azeotrope of the system, {methyl tert-butyl ether (MTBE) + methanol} using trihexyltetradecylphosphonium chloride ([P666,14][Cl]) and trihexyltetradecylphosphonium bis(2,2,4-trimethylpentyl)phosphinate ([P666,14][TMPP]). The isothermal vapor-liquid equilibrium (VLE) data at 313.15 K for the system {MTBE + methanol} with different concentrations of [P666,14][Cl] and [P666,14][TMPP] were measured using headspace gas chromatography. The mole fraction of the ILs was varied from 0.05 to 0.10. The experimental ternary VLE data were correlated using the Wilson model.

본 연구에서는 주유소 등의 지하 유류저장탱크나 파이프의 제한된 수명으로 인해 발생할 수 있는 가솔린의 누출에 의해 MTBE로 토양이 오염되었을 경우를 가정하여, 칼럼실험을 수행하고, CXTFIT 기법을 이용하여 토양 내 MTBE의 이동특성을 살펴 보았다. 칼럼실험에서는 토성, 수분함량, 유기물함량, 주입유속을 달리하여, 주입액과 유출액의 MTBE의 농도 측정값을 비교하고, CXTFIT기법을 이용하여 two-site 비평형 흡착모델에 사용된 매개변수(D, R, $\beta$, $\omega$)를 구하였다. 이들 매개변수와 파과곡선을 이용하여 MTBE의 토양 내 이동특성을 살펴보았다. 토양 내 미세입자와 유기물함량이 많을수록 이류에 의한 영향이 감소하는 것으로 나타났으며, 수분함량과 유속의 증가는 이류에 의한 MTBE의 이동을 더욱 가속시키는 것으로 나타났다.

In this stduy, the column experiments were carried out assuming the soil was contaminated by leakage of gasoline containing MTBE from USTs and pipes around gas stations. Then, characteristics of MTBE transport in the soil were investigated using CXTFIT program. The column experiments with different soil properties, moisture content, organic matter content and flow rate were carried out. Some parameters(D, R, $\beta$, $\omega$) used in two-site non-equilibrium adsorption model were obtained from measuring the MTBE concentration in injection-liquid and in effluent and using CXTFIT program. In addition, The characteristics of MTBE transport in the soil was found using BTCs and obtained parameters. Consequently, the advection decreased as the increase of the content of fine particle and organic, while the MTBE transport by advection was enhanced as increasing flow rate and moisture content.

갯벌 토양 내 미생물 군집에 미치는 methyl tert-butyl ether(MTBE)와 그의 대사산물인 tert-butyl alcohol(TBA) and formaldehyde(FA)의 영향을 조사하였다. 서로 다른 농도의 MTBE, TBA 및 FA를 갯벌 토양 microcosm에 첨가한 후 30일 간 실온에 방치했다. Microcosm 시료의 pH, 수분함량, 유기물 함량 등의 물리 화학적 특성을 측정하였다. 총 세균수와 탈수소 효소 활성변화를 측정하였고, 미생물 군집 구조는 16S rRNA-PCR-DGGE(Denaturing gradient gel electrophoresis) fingerprinting 기법을 이용해 모니터링 했다. 그 결과, MTBE, TBA 및 FA 첨가 농도와 물리 화학적 요인들 사이에는 상관관계가 없었다(P>0.05). 탈수소효소 활성과 총 세균수는 MTBE, TBA 및 FA 농도가 증가 될수록 감소하였다(P<0.05). 각각의 독성 물질들이 미생물 활성에 저해 영향을 주었으며 이들의 저해 정도는 FA > MTBE > TBA 순이었다. MTBE, TBA 및 FA 노출 후 군집의 우점종을 살펴 본 결과 Sphingobacteria, Flavobacteria, delta-proteobacteria, gamma-proteobacteria로 크게 네 그룹으로 이뤄졌다. 미생물 군집의 다양성 지수는 MTBE및 대사산물의 주입농도의 영향을 받지 않았다.

The effect of methyl tert-butyl ether (MTBE) and its metabolites like tert-butyl alcohol (TBA), and formaldehyde (FA) on microbial activity and diversity in tidal mud flat was studied. MTBE, TBA, and FA with different concentrations were added into microcosms containing tidal mud samples, and placed at room temperature for 30 days. Then the physico-chemical properties such as pH, moisture contents and organic matter contents in the microcosms were measured. In addition, the total viable cell number and dehydrogenase activity were measured. Bacterial communities in the microcosms were monitored using a 16S rRNA-PCR-DGGE (Denaturing gradient gel electrophoresis) fingerprinting method. As a result, the exposure concentrations of MTBE and its metabolites showed no correlation with the physico-chemical factors (P>0.05). Dehydrogenase activity and total viable cell number were decreased with increasing MTBE, TBA and FA concentrations (P<0.05). The toxic effect was higher the following order: FA > MTBE > TBA. Dominant species in the microcosms contaminated with MTBE and its metabolites were Sphingobacteria, Flavobacteria, delta-proteobacteria, gamma-proteobacteria. The diversity of bacterial community was not significantly influenced by MTBE and its metabolites.

In this study, the potential possibility of Oxygenates on di-ether group(butyl ether ; BE) was investigated as an additives for a naturally aspirated direct injection diesel engine. It tested to estimate change of engine performance and exhaust emission characteristics for the commercial diesel fuel and oxygenates additives blending fuel which has four kinds of mixed ratio. The smoke emission of blending fuel(diesel fuel 80vol-%+BE 20vol-%) was reduced in comparison with diesel fuel, that is, it was reduced approximately 26% at 2500rpm, full load. And, power, torque and brake specific energy consumption didn't have no large differences. But, NOx emission of blended fuel was increased compared with commercial diesel fuel. It was needed a NOx reduction counterplan that EGR method was used as a countermeasure for NOx reduction. It was found that simultaneous reduction of smoke and NOx emission was achieved with BE blended fuel and cooled EGR method.

TBA(tert-butyl alcohol)와 ethanol로부터 고체산 촉매상에서 가솔린 옥탄가 향상제인 ETBE(ethyl tert-butyl ether)의 기상 합성반응에 관하여 연구하였다. 헤테로폴리산 촉매가 제올라이트계 촉매보다 활성이 우수하였으며, $H_4SiW_{12}O_{40}$촉매는 현재 공업적으로 이용되고 있는 Amberlyst-15 수지촉매의 대체가능성을 보였다. 또한 전이금속 양이온으로 교환된 헤테로폴리산 촉매는 수소환원에 의한 새로운 산점의 생성 및 증가에 따라 촉매활성이 크게 증가되었다. 이러한 수소환원 효과는 촉매의 환원특성과 관계되며, 환원 용이성은 $Ag^+$>$Cu^{2+}$>$Fe^{2+}$의 순서였다.

Vapor-phase ETBE(ethyl tert-butyl ether) synthesis from TBA(tert-butyl alcohol) and ethanol was carried over solid acid catalysts such as heteropoly acids and proton type zeolites. Heteropoly acids were more active than proton type zeolites and $H_4SiW_{12}O_{40}$ catalyst showed about the same activity as Amberlyst-15 ion exchange resin catalyst used as an industrial catalyst in ETBE synthesis. The catalytic activity of transition metal exchanged heteropoly acids was greatly enhanced, because new acid site was generated with hydrogen reduction. This effect of hydrogen reduction was related to the reduction characteristics of catalysts and the order of reducibility was $Ag^+$>$Cu^{2+}$>$Fe^{2+}$.

요오드 2분자가 양이온(I$^{+}$)과 음이온(I$_3$$^{-}$)로 해리되어 이 매 생성된 양이온에 의한 비닐 에테르류의 양이온 중합에 관한 연구는 보고된 바 있으나$^{1)}$ 요오드를 개시제로 사용한 삼차부틸 에테르의 양이온 중합에 관한 결과가 발표된 것은 별로 눈에 뜨이지 않는다. 삼차 부틸 에테르는 단량체의 활성이 크고 중합거동이 타 비닐 에테르류와 매우 다르기 때문에$^{3),4)}$ boron trifluoride diethyl etherate를 개시제로 하고, n-햅탄 이나 톨루엔과 같은 비극성용매를 사용하여 저온에서 중합을 행한 결과만이 보고되고 있다.$^{2)-5)}$ (중략)

In this paper, the effect of oxygen component in fuel on the exhaust emissions has been investigated for an indirect injection diesel engine. It was tested to estimate change of engine performance and exhaust emission characteristics for the commercial diesel fuel and oxygenated blended fuel which has four kinds of mixed ratio. And, the effects of exhaust gas recirculation(EGR) on the characteristics of NOx emission have been investigated. Ethylene glycol mono-n-butyl ether(EGBE) contains oxygen component 27% in itself, and it is a kind of effective oxygenated fuel of mono-ether group that the smoke emission of EGBE is reduced remarkably compared with commercial diesel fuel, that is, it can supply oxygen component sufficiently at higher loads and speeds in diesel engine. It was found that simultaneous reduction of smoke and NOx was achieved with oxygenated fuel(10vol-%) and cooled EGR method(10%).

Only limited information is available on the measured exposure levels of residents according to the construction age of apartments. As such, present study was conducted to measure and to compare the bedroom, living-room, and outdoor air levels of MTBE and benzene, toluene, ethyl benzene and m,p-xylene(BTEX) in both newer and older apartments. For both newer and older apartments, all the compounds except for MTBE showed significantly higher levels in bedrooms or living-rooms as compared to the outdoor concentrations. The ratio of bedroom or living-room median concentration to outdoor concentration was close to 1 for MTBE, whereas it was larger than 1 for other target compounds. It was also found that the bedroom and living-room appeared to have similar indoor sources and sinks for BTEX, but not for MTBE. The median concentration ratios of the newer apartments to the older apartments ranged from 1.63 to 1.81, depending upon the compounds. In contrast, the MTBE concentrations did not differ significantly between the newer and older apartments, thereby suggesting that although newer buildings could emit more VOCs, this is not applicable to all VOCs. Conclusively, the findings of present study should be considered, when designing exposure studies associated with VOC emissions in buildings and/or managing indoor air quality according to construction age of buildings.

최근, 가솔린 첨가물인 Methyl tert-butyl ether (MTBE)가 음용수로 사용되는 대수층으로 방출되는 것에 대해 상당한 관심이 되고 있다. MTBE는 친수성이고, 가솔린 유출과 새고 있는 저장탱크 누출에 의해 환경에 노출되어 물과 쉽게 섞이게 된다. 본 논문에서는 실험실 규모 반응기내에서 MTBE 용액의 탈기 및 오존산화반응을 연구하였다. 계산한 질량 전달율(N)은 $1.24{\times}10^{-6}\;mol{\cdot}sec^{-1}$으로 나타났다. MTBE의 오존산화반응 실험결과 COD와 TOC는 각각 8.3%와 6.5% 감소하였고 BOD/COD는 0.03으로 큰 변화가 나타나지 않았다. 유사 1차 반응속도 상수는 $3.75{\times}10^{-5}\;sec^{-1}$으로 나타났다. 활성화 에너지는 4.80 kcal.mol-1로 나타났다.

In recent years, there has been considerable concern over the release of methyl tert-butyl ether (MTBE), a gasoline additive, into the aquifers used as potable water sources. MTBE readily dissolves in water and has entered the environment via gasoline spills and leaking storage tanks. In this study air stripping and ozonation of MTBE in aqueous solution were performed in a laboratory scale batch reacter. The mass transfer rate (N) was evaluated and a values about $1.24{\times}10^{-6}\;mol{\cdot}sec^{-1}$ was found. In the ozonation of MTBE a 8.3% decrease of the COD and a 6.5% decrease of the TOC lead to BOD/COD = 0.03. The peudo first-order rate constants of the ozonation of MTBE was $3.75{\times}10^{-5}\;sec^{-1}$. The resulting Ea of 4.80 kcal；mol-1 was observed for molecular ozone reactions.

기존의 연구를 통해 Fenton's reagent(FR)를 이용하여 MTBE의 제거가 가능하며, 그러나 중성 pH영역에서는 철이온이 수산화물로 침전되어 반응성이 낮아지므로 FR만을 이용한 처리는 높은 수소이온 농도조건(pH $3{\sim}4$)이라는 제약으로 인해 직접적인 토양 및 지하수의 MTBE 오염처리에 있어 여러 가지 어려움이 있다. 이에 본 연구에서는 효과적인 처리를 위하여 NTA, oxalate, acetate 등의 chelating agent가 철이온과 반응하여 생성된 착화합물을 이용하는 modified Fenton reaction을 도입하여 중성 pH영역에서도 철이온이 안정화되어 높은 분해효율을 나타낼 수 있도록 하였다. MTBE의 분해경향은 chelating agent의 종류와 농도, 철이온 농도 그리고 pH 변화에 따라 크게 영향을 받는 것으로 나타났다. 가장 적합한 착화합물을 선택하기 위하여 총 6개의 chelating agent(citrate, oxalate, succinate, acetate, NTA, EDTA)를 실험한 결과, 처리효율과 chelating agent의 생분해도, 독성 등을 고려하여 최종 3가지 종(oxalate, acetate, NTA)이 선정되어 이후의 실험에서는 위의 3종만을 chelating agent로 이용하였다. 동일한 실험조건($H_2O_2$ : 5%, chelating agent : 6 mM, $Fe^{3+}$ : 2 mM, pH 7)하에서의 적용성 평가한 결과, Fe-NTA가 반응시작 30분만에 99.9%의 가장 높은 제거효율을 나타내었다. Oxalate의 경우, NTA보다는 그 분해효율이 낮으나 다른 chelating agent보다 상대적으로 높은 효율(24시간 후 최대효율 : 91.3%)을 보여주며, acetate를 이용한 경우도 본 실험에서 좋은 결과(24시간 후 최대효율 : 75.8%)를 나타내었다. 또한, 적정 철이온의 농도는 oxalate가 chelating agent로 이용되면 철이온 농도가 3 mM일때 가장 큰 분해효율을 보이며, acetate의 경우는 5 mM까지 농도가 증가함에 따라 그 효율도 조금씩 증가하는 것으로 나타났다. 이와같이 MTBE의 in-situ remediation을 위한 modified Fenton 공정은 철이온을 중성 pH영역에서 안정화시켜 실제 토양에 적용하였을 때, 높은 분해효율을 얻을 수 있으며, 경제적인 자체 생분해도가 높은 저분자 유기산을 이용하였으므로 생물학적 처리와 연계를 가능하게 해주는 장점을 나타낸다. 또한 토양 내 존재하는 철광석을 촉매로 이용할 경우, 주입되는 철이온 없이도 $H_2O_2$에서의 hydroxyl radical 생성을 증가 시킬 수 있으므로 보다 경제적이고 친환경적인 처리기법을 도출해 낼 수 있다.

A recent study showed that MTBE can be degraded by Fenton's Reagent (FR). The treatment of MTBE with FR, however, has a definite limitation of extremely low pH requirement (optimum pH $3{\sim}4$) that makes the process impracticable under neutral pH condition on which the ferrous ion precipitate forming salt with hydroxyl anion, which result in the diminishment of the Fenton reaction and incompatible with biological treatment. Consequently, this process using only FR is not suitable for in-situ remediation of MTBE. In order to overcome this limitation, modified Fenton process using NTA, oxalate, and acetate as chelating reagents was introduced into this study. Modified Fenton reaction, available at near neutral pH, has been researched for the purpose of obtaining high performance of oxidation efficiency with stabilized ferrous or ferric ion by chelating agent. In the MTBE degradation experiment with modified Fenton reaction, it was observed that this reaction was influenced by some factors such as concentrations of ferric ion, hydrogen peroxide, and each chelating agent and pH. Six potential chelators including oxalate, succinate, acetate, citrate, NTA, and EDTA were tested to identify an appropriate chelator. Among them, oxalate, acetate, and NTA were selected based on their remediation efficiency and biodegradability of each chelator. Using NTA, the best result was obtained, showing more than 99.9% of MTBE degradation after 30 min at pH 7; the initial concentration of hydrogen peroxide, NTA, and ferric ion were 1470 mM, 6 mM, and 2 mM, respectively. Under the same experimental condition, the removal of MTBE using oxalate and acetate were 91.3% and 75.8%, respectively. Optimum concentration of iron ion were 3 mM using oxalate which showed the greatest removal efficiency. In case of acetate, $[MTBE]_0$ decreased gradually when concentration of iron ion increased above 5 mM. In this research, it was showed that modified Fenton reaction is proper for in-situ remediation of MTBE with great efficiency and the application of chelatimg agents, such as NTA, was able to make the ferric ion stable even at near neutral pH. In consequence, the outcomes of this study clearly showed that the modified Fenton process successfully coped with the limitation of the low pH requirement. Furthermore, the introduction of low molecular weight organic acids makes the process more available since these compounds have distinguishable biodegradability and it may be able to use natural iron mineral as catalyst for in situ remediation, so as to produce hydroxyl radical without the additional injection of ferric ion.

가솔린 옥탄가 향상제인 ETBE(ethyl tert-butyl ether) 합성반응의 촉매활성과 촉매의 산특성에 상관성 및 반응특성에 관하여 연구하였다. pyridine의 흡착량과 TBA전화율은 좋은 상관성을 보였지만, $NH_3$의 흡착량과 TBA전화율은 전이금속과 complex를 형성하는 $NH_3$의 흡착특성 때문에, 전이금속의 경우는 선형적인 상관성을 나타내지 않았다. 담지촉매의 경우, 담지량에 따른 촉매활성과 생성물 분포는 반응물인 TBA 또는 iso-butene의 흡착특성이 중요한 역할을 하였다.

Reaction characteristics and correlations between the acidic property and catalytic activity of heteropoly acid catalyst on ETBE synthesis as a gasoline octane enhancer were investigated. The amount of pyridine adsorbed on heteropoly acid catalyst and catalytic activity in the synthesis of ETBE showed a good correlation. But ammonia failed to show such a correlation because of the complex formation of ammonia adsorbed and transition metal ions. In the case of supported catalyst catalytic activity and product distribution were mainly affected by the adsorption characteristics of TBA or iso-butene.

목 적: 이 연구의 목적은 담석의 단순 X-선촬영소견에 의한 석회화 양상과 초음파소견 양상에 따라 MTBE에 대한 용해도가 어떻게 달라지는지를 밝혀내어 이 치료법에 대한 적응예를 선별하는데 도움이 되도록 하는데 있다. 대상 및 방법: 75명의 환자로부터 얻은 담낭 담석 75개를 대상으로 단순 X-선촬영과 초음파촬영을 하였다. 단순 X-선촬영소견상 나타난 석회화 양상에 따라 담석을 lucent, central calcification, diffuse calcification, laminated calcification 등 4가지 그룹으로 나누었다. 또 초음파소견을 담석의 전연의 모양과 내부에코양상에 따라 5개 그룹으로 나누어 전연이 arc 모양의 강한 에코를 내면서 내부에코가 없는 것을 그룹 1, arc 모양의 전연에코와 함께 초생달 모양의 내부에코를 보이는 것을 그룹 2, 담석의 대부분에 균질한 내부에코가 보이는 것들을 그룹3, 불균질한 내부에코를 보이는 것들을 그룹4, 담석전체의 윤곽이 나타나고 균질한 내부에코가 담석안에 가득차는 것들을 그룹 5라고 하였다. 다음 각각의 담석을 MTBE에 담구어 6시간 동안 용해시켰다. 이때 두 시간 간격으로 용해되로 남은 담석의 무게를 측정하였다. 이렇게 얻은 성적을 토대로 담석의 영상소견과 용해속도와의 관계를 후향적으로 분석하였다. 결 과: 단순 X-선촬영상의 석회화 형태에 따라 나눈 4개의 그룹들 중 lucent, central calcification의 두 그룹의 담석들은 MTBE에 잘 녹았으며 diffuse, laminated calcification의 두 그룹의 담석들은 잘 녹지 않았다.(p<,05). 초음파소견에 따라 5개로 나눈 그룹들은 다양한 용해도를 보였으나 그룹들 사이에 통계적인 의미가 있는 차이는 없었다. 그러나 석회화 양상중 잘 녹지 않았던 형태의 담석들 (diffuse, laminated calcification)을 제외한 후에는 초음파그룹5의 담석들(담석의 전체 윤곽이 그려지고 균질한 내부에코가 차는)은 거의 녹지 않은데 반해 나머지 그룹들의 담석들은 잘 녹는 뚜렷한 차이를 보였다(p<,05). 결 론: 단순 X-선촬영상 방사선투과성이거나 석회와 양상이 central인 담석으로서 초음파소견상 그룹5(전체윤곽이 그려지면서 균질한 내부에코가 꽉 차는 담석들)에 속하지 않는 담석들은 MTBE 용해술의 대상이 될 수 있다고 본다.

Purpose : The purpose of this study was to determine whether in vitro plain radiography and ultrasonography(US) could predict the outcome of gallstone dissolution with methyl tert-butyl ether(MTBE).Materials and Methods : The plain radiography and ultrasonography of 75 gallstones removed at surgery from 75 patients were obtained. The plain radiographic findings were grouped by their calcification pattern as group 1 :lucent, group 2:central, group 3:diffuse and group 4:laminated. The ultrasonographlc findings were grouped by their echo pattern as group 1 :arc shaped, clearly defined surface echo followed by distinct acoustic shadow, group 2 :strong surface echo with gradually attenuating meniscus shaped inner echo, group 3. strong surface echo with fill -in pattern of internal echo, group 4 strong surface echo with irregular inner echo and group 5:entirely discerning circumsference, homogeneous internal echotexture. After imaging, the gallstones underwent MTBE dissolution for 6 hours. The residual weight of each stone was measured every 2 hours. The correlation between imaging findings and dissolution rate was retrospectively analysed.Results : The radiolucent and central calcification stones were dissolved rapidly as compared with the diffuse and laminated calcification stones(p(.05). There was no statistically significant difference among the groups based on ultrasonographic findings alone. However, after exclusion of the certain calcification groups that were resistent to dissolution-diffuse or laminated calcification stones-all US groups except one that shows wholly circumscribed margin and homogeneous fill -in pattern of internal echo dissolved well to average 20% or less of the original weight(p(.05).Conclusion: MTBE dissolution can be tried in stones that meet both ultrasonographic (not a stone with homogeneous fill -in pattern of internal echo) and plain radiographic (radiolucent or cental calcification stone)criteria.

Advanced oxidation processes using UV and catalysts like $TiO_2$ and ZnO have been recently applied for the photocatalytic degradation of MTBE in water. Attempts have been made to replace the UV radiation by the solar spectrum. This review intends to shed more light on the work that has been done so far in this area of research. The information provided will help in crystallizing the ideas required to shift the trend from UV photocatalysis to sunlight photocatalysis. The careful optimization of the reaction parameters and the type of the dopant employed are greatly responsible for any enhancement in the degradation process. The advantage of shifting from UV photocatalysts to visible light photocatalysts can be observed when catalysts like $TiO_2$ and ZnO are doped with suitable metals. Therefore, it is expected that in the near future, the visible light photocatalysis will be the main technique applied for the remediation of water contaminated with MTBE.