Quinizarin-based simple and convenient colorimetric sensor for carbon dioxide

성민석 서울대학교 대학원 2017 국내석사

Abstract Quinizarin-based Simple and Convenient Colorimetric Sensor for Carbon Dioxide MinSeok Seong Department of Materials Science and Engineering The Graduate School Seoul National University In search of simple and fast method to estimate the concentration of atmospheric carbon dioxide, the quinizarin and TBD system was discovered and its mechanism was studied and the applications were tried. From UV-VIS spectrum, the reason behind the change in color of the solution was found to be the different electronic forms of quinizarin. In other words, the color of the quinizarin solution was orange yellow when quinizarin was neutral while its color changed to purple once mixed with TBD as a result of deprotonation. Also, the molar ratio of quinizarin to TBD was 1 to 1 because there was no increase in the strength of the absorption band when TBD was excessive whilst there was a decrease when TBD was deficit. Also, the shift of the absorption band was observed as a result of TBD binding with carbon dioxide and giving back protons to quinizarin. From 1H-NMR spectrum, the hydroxyl proton of quinizarin was observed initially but it was soon given to TBD. Also, the fact that TBD bound itself with carbon dioxide was verified by the 13C-NMR spectrum as a new peak was observed at 161 ppm. In assistance with FT-IR spectrums, the proposed mechanism was supported once more. Quinizarin loses a proton to TBD and the protonated TBD loses the proton as it binds with carbon dioxide. As a result, the color of the solution changed from purple to yellow. The intensity of the vibrational modes for the corresponding functional groups changed accordingly; N-H bond decreased and O-H bond increased. For the experimental parts, the saturation volume of carbon dioxide was studied; the total volumetric capacity of the detecting system at different concentrations were measured and it was used to estimate the approximate response time and detectable concentration of carbon dioxide for each concentration of the system. The response time of the system at given concentration of carbon dioxide was figured out in the next step. As predicted, the system with lower concentrations of the chemicals had a shorter response time. However, the systems with the other organic bases such as DBU and piperidine were found to be not fast enough to detect the concentration of carbon dioxide fast compared to the system with TBD at the same concentration. Most importantly, the system could be recycled for at least 3 to 5 times and the performance was maintained relatively well. The system could actually be re-used upto 10 times but it became harder and harder to notice the color change when re-used too many times. Known the properties of the system as sensor, new applications were tried.. For solidification, TBD was physically fixed onto silica and it was successfully done. Nextly, the solid TBD was dipped in the quinizarin solution to become blue. Although the system was seemingly ready, it was not be able to interact with the atmospheric carbon dioxide and did not undergo any color change. Obviously, the solid system failed to interact with carbon dioxide because of too high thermodynamic barrier between solid and gas. The other option was an Agarose gel technique. The quinizarin and TBD solution was made and mixed with hot agarose solution and cooled down. However, the gel had too much viscosity so the response time was significantly increased. Keywords: Carbon dioxide, Chemical dye, Organic base, Protonation, Deprotonation, Adduct, Colorimetric sensor, Student Number: 2015-20829

Catalytic investigations of Chitosan, Ionic Liquids, and Metal Oxide based materials towards the fixation of carbon dioxide into dimethyl carbonate

Tamboli Ashif Hiralal Tamboli Ashif Hiralal 2017 해외박사

Catalytic investigations of Chitosan, Ionic Liquids, and Metal Oxide based materials towards the fixation of carbon dioxide into dimethyl carbonate Tamboli Ashif Hiralal Department of Energy Science and Technology Graduate School, Myongji University Directed by Professor Kim Hern This study gives emphasis to the use of naturally abundant, recyclable and inexpensive materials (carbon dioxide, chitosan, and urea) with simplistic and eco-friendly methods (microwave) in the synthesis of highly active catalysts for dimethyl carbonate production from carbon dioxide and methanol. A wide range of catalyst materials has been synthesized such as polymeric, ionic liquids, polyionic liquids ion-gels, metal oxides and solid solutions with novel structures and properties. Carbon dioxide is the chief offender of greenhouse effect which creates vital environmental crisis including global warming, air pollution, and acid precipitation. At the same time, carbon dioxide is naturally abundant, inexpensive, and recyclable future carbon feedstock. In this regards, development of a novel process for the effective utilization of carbon dioxide from the ecological and economical point of view has been the major challenges to the research community. Inspiring by the fact, we took this opportunity to design and synthesize a novel catalyst materials for single step conversion of carbon dioxide into valuable chemical such as dimethyl carbonate. In the development of sustainable and green chemical processes, dimethyl carbonates play a crucial role because of their nonhazardous and environmentally friendly nature having a broad range of applications as solvents, fuel additives, reactants, etc. Although direct dimethyl carbonate synthesis from carbon dioxide and methanol is green and attractive, it is suffering from low yield and thermodynamic limitations. Therefore, an active catalyst is needed for the activation of carbon dioxide and dehydrating agent to remove water from the reaction medium. To overcome these challenges, three types of catalyst materials have been synthesized including naturally abundant chitosan dissolved ionic liquids and chitosan grafted amine derivatives which are composed of carbon dioxide philic amino and hydroxyl groups. These catalyst systems exhibited excellent catalytic activity with methanol conversion in a range of 16.90 to 23.8% and about 99% dimethyl carbonate selectivity. In the next study, a new class of material i.e. polyionic ionic liquid/ ionic liquid ion-gel has been designed with a very high number of free ionic liquids monomer and carbon dioxide permeability. The ion-gel was synthesized by the polymerization of novel carboxyl functionalized vinyl and methylimidazole based ionic liquids. The resulting ion-gel catalyst showed excellent methanol conversion of up to 21.51% with 99% dimethyl carbonate selectivity at ambient reaction conditions. Additionally, the reaction mechanism was proposed with the help of carbon dioxide-ionic liquids interactions and 13C NMR spectroscopy. The conclusive work was focused on the synthesis of metal oxides and solid solutions of ceria, zirconia, Samaria and ceria-zirconia with various morphologies and high surface area for direct dimethyl carbonate production. The main objective of this work was to evaluate the role of catalyst morphology, surface properties and dehydrating agent on the catalytic activity towards direct dimethyl carbonate synthesis. Experimental results revealed that the spindle-shaped morphology offers both higher surface area and catalyst activity, whereas dehydrating agents played an important role and increased product yield effectively. In short, the present study suggests that the novel catalyst systems possessing either carbon dioxide philic functional groups such as amino, hydroxyl, and carboxyl or high carbon dioxide permeability or novel morphology and dehydrating agent are needed for efficient conversion of carbon dioxide. Furthermore, extensive studies are necessary for the determination of reaction mechanism to scale up the title reaction at the industrial level. We hope that this study will offer a new avenue in areas of catalytic processes. 이산화탄소의 디메틸 카보네이트 고정화용 키토산, 이온성 액체 및 금속산화물 기반 소재의 촉매 연구 탐볼리 아시프 히랄랄 명지대학교 대학원 에너지융합공학과 지도교수: 김 헌 본 연구는, 이산화탄소와 메탄올로부터 디메틸 카보네이트 생산용 고활성 촉매의 합성에서, 자연에 풍부하고 재생가능하며 값싼 소재 (이산화탄소, 키토산, 요소)를 사용하고 단순하며 환경친화적인 방법을 개발하는 데 중점을 둔다. 고분자, 이온성 액체, 고분자 이온성 액체 이온젤, 산화금속, 고체 용액 등 새로운 구조와 물성을 지니는 다양한 범주의 촉매 물질이 합성되었다. 이산화탄소는 지구온난화, 대기오염, 산성비 등을 포함하는 실제적 환경문제에 영향을 주는 온실가스의 주범으로 알려져 있다. 동시에, 이산화탄소는 자연적으로 풍부하고 저렴하며 재생가능한 미래 탄소원이기도 하다. 이러한 관점에서 이산화탄소를 효과적으로 이용할 수 있는 새로운 공정의 개발이 환경 및 경제적인 관점에서 대두되고 있다. 이 사실로부터, 본 연구에서는 이산화탄소를 이용하여 디메틸 카보네이트와 같은 부가가치가 큰 화학제품을 단일공정으로 전환시킬 수 있는 새로운 촉매 물질을 설계하고 합성하는 데 목적을 둔다. 지속가능하며 친환경적인 화학공정에서, 디메틸 카보네이트는 무해하며 친환경적인 특성 때문에 다양한 범주의 용매, 연료 첨가제, 반응물 등의 용도를 가지는 중요한 역할을 담당한다. 이산화탄소와 메탄올로부터 디메틸 카보네이트를 직접 생산하는 방법은 친환경적이고 매력적이지만, 수율이 낮고 열역학적인 제한을 받는다. 그러므로 활성화 촉매는, 이산화탄소의 활성화 및 반응물로부터 물을 제거하기 위한 탈수화 용액이 필요하다. 이러한 도전을 극복하기 위하여 3종류의 촉매 물질이 합성 된다. 자연에 풍부한, 이온성 액체에 용해되는 키토산, 키토산 그래프트 아민 유도체 (친이산화탄소 아미노 및 하이트록실기로 구성). 이들 촉매 시스템은 우수한 메탄올 전환 촉매 활성도 (16.9-23.8%) 및 약 99% 디메틸 카보네이트 선택도를 보인다. 다음 연구에서, 새로운 군의 소재, 즉 고분자 이온성 액체/이온성 액체 이온젤 등이, 매우 높은 수의 자유 이온성 액체 모노머와 이산화탄소 투과도를 가지고 설계된다. 이온젤은 새로운 카르복실 기능화된 비닐 및 메틸이미다졸 기반 이온성 액체들의 고분자화를 통하여 합성된다. 결과로 얻는 이온젤 촉매는 21.51%정도까지의 높은 메탄올 전환율 및 99% 디메틸 카보네이트 선택도를 보여준다. 더욱이, 반응 메커니즘은 이산화탄소-이온성 액체 상호작용 및 13C NMR 분광기로 분석된다. 결론적으로, 세리아, 지르코니아, 사마리아, 세리아-지르코니아의 금속산화물, 고체용액의 합성을 촛점을 맞추며 여기서 다양한 구조 형상 및 고표면적을 구현한다. 본 연구의 주된 목적은 촉매 형상의 역할, 표면 물성, 탈수 용액 등의 직접 디메틸 카보네이트 직접 합성시 촉매 활성에 미치는 영향 등을 조사하는 데 있다. 실험 결과들로서, 스피넬-골격의 형상은 보다 큰 표면적 및 촉매 활성도를 제공한다. 한편 탈수 용액은 효과적으로 수율을 증대시키는 중요한 역할을 담당한다. 본 연구는, 아미노, 하이드록시, 카보닐 등과 같은 친이산화탄소 기능성 그룹 또는 새로운 이산화탄소 투과성 또는 새로운 현상, 탈수 용액 등에 대한 고려가 효과적인 이산화탄소 전환을 보장함을 보여 주었다. 더욱이, 반응 메커니즘의 결정, 대량생산을 위한 검토 등의 추가적인 연구를 동반할 수 있다 키워드: 이산화탄소, 온실가스, 디메틸 카보네이트, 촉매, 이온성 액체, 산화금속, 복합체, 수율, 선택도, 활성도

Numerical modeling of impacts of cleat spacing and formation dip on geologic storage of carbon dioxide in coal beds

김창수 서울대학교 대학원 2013 국내석사

Carbon dioxide emission into the atmosphere is considered as the cause of global warming and geologic storage of carbon dioxide is one of the most effective and safe way to reduce carbon dioxide concentration. There are several types of formation for geologic storage of carbon dioxide and coal beds receive attention due to its high efficiency of storage and additional production of methane which can reduce the implementation cost of geologic storage of carbon dioxide. In this study, a series of numerical simulations using a multi-dimensional thermo-hydrogeological-chemical numerical model is performed to analyze migration and adsorption of fluids (carbon dioxide, methane, and groundwater) and to estimate the influences of the cleat spacing and the formation dip on them due to geologic storage of carbon dioxide in coal beds. A conceptual model of simulation is based on Samcheock coal field which is the largest coal field in Korea to consider features of domestic coal field. The results of the numerical simulations show that fluids flow in the coal cleat is impacted by the variation of cleat spacing and formation dip. The results of a series of numerical simulations show that up to the 88% of carbon dioxide are adsorbed in the matrix regardless of variation of cleat spacing or formation dip. And most of injected carbon dioxide migrates and are adsorbed to the top boundary of coal beds. Methane and groundwater are pushed to the outside from injection well by carbon dioxide, and some methane is adsorbed again in the carbon dioxide adsorbed area. The results of sensitive analysis of cleat spacing show that spatial distribution of carbon dioxide, methane and groundwater are impacted by change of cleat spacing. According to decreasing of cleat spacing, the more carbon dioxide and methane flows up to the boundary of coal beds, and the influenced areas of carbon dioxide increase. Results of sensitive analysis of formation dip show that flows of fluids are significantly affected by formation dip. Carbon dioxide and methane flow rapidly in the direction toward surface. Velocities of carbon dioxide and methane flow are drastically increased according to increasing of formation dip. As a result, some methane and carbon dioxide moves out of the domain. Results of this study show that a multi-dimensional thermo-hydrogeological-chemical numerical model is useful to predict complex migration and adsorption mechanism of fluids due to geologic storage of carbon dioxide. And results of this study are expected to contribute to establish reasonable and effective plan of geologic storage of carbon dioxide.

Valorization and Optimization Studies of Carbon Dioxide to Terpenoids in Rhodobacter sphaeroides

이유림 전남대학교 2024 국내박사

The climate crisis has intensified due to the continuously increasing carbon dioxide emissions. To mitigate carbon dioxide, various carbon capture utilization (CCU) technologies have been proposed recently. It is regarded as a notable and sustainable approach for counteracting the crisis because it converts carbon dioxide into practical valuable materials. In particular, the biological conversion of carbon dioxide is suggested as an attractive and environmentally friendly approach owing to the ambient conversion process and its ability to produce long-chain hydrocarbon materials, such as terpenoids. Rhodobacter sphaeroides is a suitable microorganism for the process of converting carbon dioxide into high-value materials because it can accept carbon dioxide and has versatile metabolic pathways. However, previous studies have been mainly reported for heterotrophic growth that uses sugars and organic acids as carbon sources, not autotrophic growth. Here, I report that the regulation of reactive oxygen species (ROS) is critical for growth when using carbon dioxide as a sole carbon source in R. sphaeroides. In general, the growth rate is much slower under autotrophic conditions compared to heterotrophic conditions. To improve this, I performed random mutagenesis using N-methyl-N’-nitro-N- nitrosoguanidine (NTG). As a result, I selected the YR-1 strain with a maximum specific growth rate (µ) of 1.44 day-1 in the early growth phase, which has a 110 % faster growth rate compared to the wild-type. Based on the transcriptome analysis, it was confirmed that the growth was more sensitive to ROS under autotrophic conditions. In the YR-1 mutant, the endogenous contents of H2O2 levels and oxidative damage were reduced by 33.3 and 42.7 % in the cells, respectively. Furthermore, I measured the concentrations of carotenoids, which are important antioxidants. The total carotenoid is produced at 9.63 mg/L in the YR-1 mutant, suggesting that the production is 1.7-fold higher than wild-type. Taken together, these observations indicate that controlling ROS promotes cell growth and carotenoid production under autotrophic conditions. Microbial electrosynthesis (MES) using electroactive autotrophic microorganisms has recently been reported as a method to reduce carbon dioxide. However, there are still few cases of MES application, and the molecular mechanisms are largely unknown. To investigate the growth characteristics in MES, I carried out growth tests according to reducing power sources in R. sphaeroides. The growth rate was significantly lower when electrons were directly supplied to cells, compared to when hydrogen was supplied. Through transcriptome analysis, I found that the expression of ROS-related genes was meaningfully higher in MES than in normal photoautotrophic conditions. Similarly, endogenous contents of H2O2 were higher and peroxidase activities were lower in MES. The exogenous application of ascorbic acid, a representative biological antioxidant, promotes cell growth by decreasing ROS levels, confirming the inhibitory effects of ROS on MES. Altogether, these observations suggest that the reduction of ROS by increasing antioxidant activities is important for enhancing the cell growth and production of CO2-converting substances such as carotenoids in MES. Biofuels have been proposed as a sustainable alternative to replace fossil fuels and overcome the climate crisis. One of the sesquiterpenoids, farnesene, is considered a crucial precursor for bio-jet fuel owing to its low hygroscopicity and high energy density. This study reports the high yield of β-farnesene production from CO2 by expressing heterologous β- farnesene synthase (FS) into R. sphaeroides. To increase the expression of FS, a strong active promoter and a ribosome binding site (RBS) were engineered. Moreover, β-farnesene production was improved further through the supply of exogenous antioxidants and additional nutrients. Finally, β-farnesene was produced from CO2 at a titer of 44.53 mg/L and yield of 234.08 mg/g, values that were correspondingly 23 times and 46 times higher than those from the initial production of β-farnesene. These results suggest a practicable approach to enhance β-farnesene production under autotrophic conditions. To summarize, this dissertation proposes several strategies for biological carbon dioxide valorization into terpenoids including carotenoids and β-farnesene, indicating that it can provide a starting point for achieving a circular carbon economy.

미니 돼지에서 Isoflurane 마취 후 각성 시 이산화탄소 흡입제의 영향

조기래 충북대학교 2015 국내박사

Prevention of delayed emergence is one of valuable policies for reducing post-anesthetic complications. Recovery from inhalation anesthesia is achieved by elimination of the volatile anesthetic agent from the body, especially from the central nervous system by lowering anesthetic concentration in brain tissue. The elimination of inhalational anesthetics depends on various factors including alveolar ventilation, cardiac output, and the agent’s blood solubility. Because the major route for elimination of inhalational anesthetics is the alveolus, hyperventilation can facilitate removal of volatile anesthetics through pulmonary elimination via the increase in respiratory rate or tidal volume. However, increased ventilation can also reduce arterial partial pressure of carbon dioxide which may result in post-hyperventilation apnea and decline of cerebral blood flow. In previous studies, it was demonstrated that isocapnic and hypercapnic hyperventilation shortened recovery time. There is no study about the effect of carbon dioxide insufflations without hyperventilation. Therefore the aim of this study was to evaluate the effect of different concentrations of carbon dioxide insufflation without ventilatory intervention on emergence time from inhalation anesthesia and acid-base status. Azaperone-sedated miniature pigs receiving propofol for induction were anesthetized with 2.0% isoflurane for 1 hour. After turning off the ventilator, the gas mixture of oxygen with carbon dioxide (0%, 2%, 4%, 6%, and 8%) was supplied through the endotracheal tube using self-manufactured carbon dioxide delivery equipment. The concentration of carbon dioxide was measured by sidestream infrared analyzer. Monitoring of respiratory parameters was performed from the end of anesthesia to extubation, including isoflurane concentration, respiratory rate, minute ventilation, and end-tidal carbon dioxide concentration. Arterial blood gas analysis was carried out for monitoring pH, HCO3-, PCO2, and TCO2 with 5 minutes’ intervals. Time to extubation and standing were evaluated as indicators of anesthetic emergence. End-tidal isoflurane concentration, respiratory rate, and minute ventilation rapidly decreased, and end-tidal carbon dioxide concentration increased with the increased concentration of carbon dioxide insufflation. Carbon dioxide insufflation reduced arterial blood pH in a statistically significant manner, but remained within the reference range except for 8% carbon dioxide group. HCO3- also reduced but it was not clinically relevant. PCO2 and TCO2 increased with the increased carbon dioxide insufflation, however, it was not clinically significant. Time to extubation and standing shortened with carbon dioxide administration, and the shortest ones were found in 6% carbon dioxide group. The increase of carbon dioxide concentration accelerated elimination of isoflurane and increased respiratory parameters such as respiratory rate and minute ventilation. Arterial blood gas analysis demonstrated that carbon dioxide insufflations reduce arterial blood pH, within the reference range, it is presumed that the acid-base buffer system such as HCO3- minimize pH changes from CO2 insufflation. The most rapid emergence from general anesthesia was found in 6% carbon dioxide group rather than 8% carbon dioxide group. The most rapid emergence from general anesthesia was found in 6% carbon dioxide group rather than 8% carbon dioxide group. These results were not fully explained in this study, however it might be involved in the central inhibitory effect of carbon dioxide. Given the effect of acid-base status and the rapidity of anesthetic emergence, 6% carbon dioxide could be most appropriate for clinical application. 흡입 마취에서 빠른 회복은 수술후의 마취 합병증의 감소에 중요하다. 흡입 마취에서의 회복은 체내, 특히 중추신경계에서 마취제의 제거에 의해 달성된다. 이러한 흡입마취제의 제거는 폐포 환기, 심박출량, 흡입마취제의 용해도 등 다양한 요소에 의해 영향을 받는다. 그러나 흡입마취에서 동맥혈액과 폐포 사이의 마취제의 분압은 균형을 이루기 때문에 마취제의 제거는 폐포 환기에 영향은 중요하며 마취제거의 조절이 손쉬운 부분이다. 과환기는 호흡수와 일회호흡량을 증가시켜 흡입 마취제를 폐포 즉, 동맥혈액으로부터 제거하는 좋은 방법이다. 하지만 과환기는 급속히 동맥혈액의 이산화탄소 분압을 낮추게 되어 과환기후 무호흡과 동맥혈액 흐름을 감소시켜 결국 중추신경계로부터 흡입마취제의 방법을 감소하게 된다. 과거 연구에서 이러한 것 작용을 해결하기 위해 과이산화탄소혈증 또는 정상 이산화탄소혈증 상태에서 과환기하여 마취 회복시간의 단축을 확인하였다. 즉, 동맥혈액 이산화탄소의 일정 농도는 호흡수와 일회호흡량 증가로 흡입마취제의 빠른 회복에 도움을 주는 것이다. 하지만 과환기 없이, 특정 이산화탄소의 농도에서 가장 빠른 마취제의 회복을 연구는 되지 않았다. 이 연구에서 공급 이산화탄소의 농도에 따라 빠른 마취회복에 영향을 주는 요소를 확인함과 동시에 동맥혈액가스분석을 통해 항상성에 영향 정도를 확인하는 것이다. 미니 돼지 10마리중에서 4마리를 선택하고 azaperone으로 진정 후, propofol로 마취 유도한 후 기관내관을 삽관하고 2.0% isoflurane으로 기계적 환기를 1시간 동안 유지하였다. 기화기 종료 후, 산소 공급하에 0%, 2%, 4%, 6%, 그리고 8%의 농도로 이산화탄소를 기관내관을 통해 공급하였다. 이때 이산화탄소 공급을 위한 장치를 제작하였으며, 공급 이산화탄소의 농도를 확인하기 위해 sidestream analyzer를 사용하였다. 기화기 종료를 0분으로 하여 분단위로 발관까지 호흡 관련 지표를 측정하였다. 측정 지표로 isoflurane의 농도변화, 호흡수, 분당환기량, 그리고 호기말 이산화탄소 농도이다. 대퇴동맥에서 채혈한 동맥혈액가스 측정 지표는 pH, HCO3-, PCO2, 그리고 TCO2이며 기화기 종료 후, 그리고 5분 간격으로 측정하였다. 그리고 마취회복의 지표로 후두반사가 있을 때의 발관시간과 사지로 완전히 기립하는 최초시간인 기립시간을 확인하였다. 이산화탄소의 공급의 증가에 따라 호기말 isoflurane의 농도, 호흡수, 분당 환기량 급속히 감소하였으며, 호기말의 이산화탄소 농도는 증가함을 보여 주었다. 동맥혈액가스 측정에서 이산화탄소 공급에 따라 pH는 감소하는 양상을 보여주었으나 8%의 이산화탄소를 공급을 제외하고 비교적 정상범위에 위치하였으며, 통계적으로 유의적인 감소를 보여 주었다. HCO3-는 감소의 양상을 보였으나 임상적으로 중요하게 감소되지는 않았다. PCO2와 TCO2는 이산화탄소 공급에 따라 증가하는 양상을 보였으나 임상적으로 중요하게 감소되지는 않았다. 발관시간과 기립시간은 이산화탄소 공급에 따라 짧아지는 양상으로 보였으나 6%의 이산화탄소 농도에서 가장 짧은 시간을 보였다. 이산화탄소의 공급의 증가는 isoflurane의 배출과 호흡관련 지표의 증가를 촉진한 것으로 확인되었다. 특히, 호흡수와 환기량의 증가는 그 증가가 명확하였으며, 이에 비례하여 isoflurane의 배출 역시 이산화탄소 공급에 따라 증가함을 확인하였다. 동맥혈액가스 분석을 통해서도 8%의 이산화탄소 공급에서 비교적 정상범위에서 벗어난 pH의 변화를 확인 하였을 뿐 다른 이산화탄소 농도에서는 pH는 정상 범위를 유지하였다. 이는 이산화탄소의 공급이 동맥혈내 pH의 변화를 유발하는 것은 사실이지만 그 농도 변화를 유발하는 정도는 다른 산-염기 완충인 HCO3- 등이 작용하는 것으로 보여진다. 이산화탄소의 공급에 따른 발관 시간과 기립시간에서 6%의 이산화탄소 공급이 가장 짧은 시간을 보였다. 이러한 결과는 이산화탄소 공급량에 따른 빠른 isoflurane의 배출의 결과와 상충되는 결과이다. 그러한 원인으로 고려될 수 있는 것은 이산화탄소의 중추억제의 효과로 생각될 수 있다. 즉, 고농도의 이산화탄소 혈증이 호흡중추의 자극을 통한 환기량 증가로 isoflurane의 배출을 촉진하지만 이산화탄소의 중추억압 효과이므로 최적의 이산화탄소 공급량의 산-염기 균형을 고려할 때 6%의 이산화탄소 공급이 적절한 것으로 판단된다.

Inactivation of pathogenic microorganisms using supercritical carbon dioxide

박형석 Graduate School, Korea University 2012 국내박사

The overall objective of this dissertation was to investigate the effects of supercritical carbon dioxide (SC-CO2) on the inactivation of pathogenic fungi, bacterial spores or biofilms formation. The sterilization conditions of SC-CO2 on the Penicillium oxalicum and Alternaria brassicicola spores were optimized by response surface methodology (RSM). The optimum conditions for their inactivation of those fungal spores were as follows: 168 bar and 49°C for 20 min with a predicted expected inactivation yield of 5.74 logs and 196 bar and 46°C for 17 min with a predicted inactivation yield 6.37 of logs, respectively. The synergistic effect of cosolvent modifier (ethanol) on the SC-CO2 inactivation of P. oxalicum and A. brassicicola spores were investigated. When SC-CO2 treatments were conducted under severe conditions such as 100 bar and 40°C and 150 bar and 38°C, both spores were completely inactivated (i.e., log10 reduction of 7) within 45 min by SC-CO2 modified with cosolvent. However, pure SC-CO2 without cosolvent required longer treatment time (90 min) for complete inactivation of both spores. Moreover, confocal laser scanning microscopy and scanning electron microscopy analysis of spores revealed that the SC-CO2 treated spores caused damage to membrane integrity or structures of spores. To examine the inactivation of fungus grown on grains and their germination caused by the SC-CO2 treatment, wheat and barley grarins were contaminated by P. oxalicum spores. The inactivation conditions of their grains were optimized by RSM. The inactivation yields increased as all independent variables increased. Espccially, the inactivation yields of P. oxalicum spores were significantly affected by amount of water cosolvent. The optimal conditions of water content, treatment temperature and time were obtained by ridge analysis such as 233 µl, 44°C and 11 min for 6.41 log reductions for wheat and 231 µl, 44°C, 12 min for 6.75 log reductions for barley. However, the germination capabilities of wheat and barley grains were significantly reduced by the addition of water cosolvent to SC-CO2. The SC-CO2 was applied to the inactivation of Bacillus cereus and Candida albicans spores in biofilm. B. cereus vegetative cells in biofilm were completely inactivated at the treatment pressure of 100 bar for 5 min at 35°C. However, SC-CO2 did not inactivate the spores in biofilm under pasteurizing temperature (i.e., no higher than 60°C) even though pressure and treatment time increased. At pasteurizing conditions such as 100 bar and 60°C, when SC-CO2 with small amounts of modifier was treated for 60 min, B. cereus spores in biofilm were complete inactivate by modified-SC-CO2 treatment. The inactivation yield of C. albicans spores in biofilm dramatically increased as the treatment pressure and temperature increased. However, C. albicans planktonic spores and dry biofilm showed higher resistance to pressure or temperature than wet biofilm. Additionally, membrane integrity changes of the SC-CO2 treated planktonic spores or biofilm spores were observed by confocal laser scanning microscopy. Therefore, supercritical carbon dioxide, especially with a cosolvent modification may offer a new way to sterilize pathogenic microorganisms relatively at a moderate condition, and it is also expected to exploite in many other areas such foods, medical devices and pharmaceutics.

Experimental Study on Effects of Carbon Dioxide to the Thermal Desalination System : 열 담수화 장치에서 이산화탄소의 배출에 관한 실험적 연구

바야라 나산 경상대학교 대학원 2012 국내석사

열 담수화 시스템에서 용해된 비 응결 가스(NGC)의 발생은 응축 열 전달 저하, 에너지 소비량은 증가하는 심각한 문제이다. NGC는 주로 질소 (N2), 산소 (O2), 아르곤 (Ar)와 이산화탄소 (CO2) 등 다른 가스로 구성되어 있다. 그러나 이산화탄소는 해수에 화학적으로 용해되고, 스케일형성에 밀접하게 관련 되어있다. 그러므로 스케일 형성을 예측할 수 있는 적절한 과정의 이해와 적절한 방출시스템을 사용하는 것이 필요하다. 이 연구의 목적은 열 담수 시스템에서 발생하는 NGC의 복잡함을 밝혀내는 것 이다. 특히 그 중에서도 해수에 화학적으로 반응하는 이산화탄소와 그것이 어떻게 스케일 형성에 영향을 미치는 대한 복잡함을 밝히는 것이다. 본 논문에서는 열 담수 시스템의 성능, 이산화탄소의 발생, 염수와 담수에 영향 등이 실험실 규모로 조사되어 졌다. 단일 효용 증발관는 산업에 적용하기에 제한되어 있고, 선박과 다중효용법를 개발하는데 주로 사용되고 있다. 이 논문에서는 단일 효용 증발관를 선택하여 사용 했다. 증발기 세포의 10개의 티타늄 가열 튜브는 해수증발을 위해 수평으로 설치 되었고, 물이 가열튜브를 가열시키는 증기로 사용되었다. 그리고 그것은 온도를 제어하기 위한 전열기에 연결되어 있다. 끓는 온도는 증발 셀의 압력에 의해 제어 되어진다. 실험연구는 단계로 나누어져 있다. 첫째로 시스템 성능을 분석하고 둘째로 이산화탄소의 발생을 조사하기 위해 해수를 분석하고, 증발 온도와 예열기의 온도가 실험 진행의 매개 변수로 사용하였다. 성능 테스트 분석은 증발기 압력에 의해 제어되는 다양한 끓는 온도 범위에서 실시 하였다. 해수 분석에 관해서는 염분와 PH가 매개 변수로 사용되었고, 그것은 휴대용 염분측정기와 PH측정기로 측정 하였다. 마지막 결과는 이산화탄소 배출비율이 끓는 온도에 직접적인 영향을 미치는 것을 확인 할 수 있었다. 또 다른 문제는 이산화탄소가 응결수에 쉽게 흡착되는 것 이다. In the thermal desalination system release of dissolved non-condensable gases (NCG) are serious problem with reducing heat transfer for condensation, energy consumption and more. NCG mainly contains few different gases which are the nitrogen (N2), oxygen (O2), argon (Ar) and carbon dioxide (CO2). However only carbon dioxide (CO2) chemically dissolves in seawater, reacts with concentration component of seawater and closely related to scale formation. Therefore it’s necessary to understand proper progress to predict scale formation and use proper venting system. The aim of the study is reveal the complication of the non-condensable gases release from the thermal desalination system, especially the carbon dioxide which reacts with chemically to the concentration components of the seawater and how it is related to scale formation. In this thesis, performance of thermal desalination system, release of carbon dioxide and effects to brine and distillate are investigated in laboratory scale. Single-effect distillers have very limited industrial application and mainly used in marine vessels, development to the multi-effect distillers. Single-effect distiller is chosen as thermal desalination system in this study. In the evaporation cell 10 titanium heating tubes are placed in horizontal directions to evaporate the seawater. General water is used as steam to heat the heating tubes and is connected to the electric heater to control temperature. Boiling temperature is controlled by pressure of the evaporation cell. The experimental study has divided into stages, firstly analyse system performance and secondly analyse the seawater to investigate the release of carbon dioxide. The evaporation temperature and preheater temperature are chosen as parameters of the experimental progress. The performance test analyse has been conducted in various boiling temperature ranges which controlled by evaporator pressure. As for the seawater analyse, salinity and pH are used as main parameters and it is tested by portable salt meter and pH meter. Finally the results were showed that release of carbon dioxide rate has directly influenced by boiling temperature. Another matter is released carbon dioxide has easily adsorbed to condensed water.

Stripping Systems for Removing Dissolved Carbon Dioxide in Anaerobic Digestate of Food Waste : 음식물쓰레기 혐기소화액 내 이산화탄소 탈기를 위한 최적 탈기 조건 확립

강진영 명지대학교 대학원 2016 국내석사

Anaerobic digestate of organic wastes often contains high concentrations of ammonia and carbon dioxide. Ammonia can be removed from digestate by air stripping at elevated pH. However it is difficult to increase pH of digestate because dissolved carbon dioxide transforms into bicarbonate and carbonate ions. Thus, carbon dioxide in digestate needs to be removed to reduce alkali consumption in ammonia stripping process. This study aimed to optimize and compare the performances of diffused and packed tower aerators for anaerobic digestate of food waste. Under the optimized conditions with digestate temperature of 45ºC, air flow rate of 3 vvm, aspect ratio of 2, agitation speed of 500 rpm with a turbine impeller, and retention time of 10 min, the diffused aerator removed 82.1% of dissolved carbon dioxide and 13.7% of total inorganic carbon, and pH of the digestate increased from pH 7.87 to pH 8.53. Also, the alkali chemical dosage of digestate was reduced to 27.2% compared with untreated digestate, during carbon dioxide stripping process. Operating conditions of the packed tower aerator were also optimized, but it was found that the packed tower aerator removed 15%, 44%, and 15% less effectively to dissolved carbon dioxide, total inorganic carbon, and alkali chemical dosage, respectively, than the diffused aerator. It was also found that overall mass transfer coefficient determined pH of digestate and removal efficiencies of carbon species, which indicated that optimization of stripping reactors needs to be carried out for enhancing mass transfer from liquid to gas phases.

(A)study on the solubility of water in carbon dioxide using an indirect measurement method

김영조 Graduate School, Korea University 2010 국내석사

지구 온난화를 유발하는 물질 중 가장 큰 부분을 차지하는 이산화탄소의 배출을 줄이는 것이 최근 전 세계가 직면한 문제이다. 하지만 갑자기 이산화탄소의 배출량을 줄이는 것이 쉽지 않기 때문에 배출되는 이산화탄소를 심해저나 지중에 장시간 저장하는 방법이 제안되었고 연구가 이루어져왔다. 그 중 석탄층 내에 이산화탄소를 저장하는 방법이 많은 연구자들에 의해 연구되어 왔으며 초임계 이산화탄소의 경우 800 m 이상의 깊이에 저장이 가능하다. 일반적으로 그 온도와 압력 조건은 땅 속으로 1 km 내려갈 때마다 온도는 25 K, 압력은 105 bar가 증가하는 것으로 보고되어있다. 이산화탄소를 석탄층에 저장하는 경우 이산화탄소에 포함된 물이 불순물로 작용할 수 있기 때문에 물과 이산화탄소의 상호 용해도 데이터를 측정하는 것이 중요하다. 과량의 물에 녹는 이산화탄소의 양을 측정하는 것은 어렵지 않고 측정방법이 잘 알려져 있기 때문에 발표된 데이터 간의 경향성이 뚜렷하지만 과량의 이산화탄소에 녹는 물의 양은 측정 및 분석 방법이 어렵기 때문에 데이터 사이의 차이가 심하다. 이번 연구에서는 간접 측정 방법을 이용하여 과량의 이산화탄소에 녹는 물의 용해도를 측정하였다. 그 결과 8개의 데이터를 얻을 수 있었으며 조성과 온도의 불확도는 각각 1.0E-4와 0.1 K이었다. 측정된 결과는 물의 회합(association)과 물과 이산화탄소 사이의 용매화(salvation)를 고려하여 Cubic Plus Association Equation of State (EoS)와 Nonrandom Lattice Fluid with Hydrogen Bonding EoS를 이용하여 계산, 분석하였으며 그 결과 두 종류의 상태방정식 모두 실험 불확도 이내에서 계산 가능한 것을 확인할 수 있었다. Carbon dioxide occupies the largest portion of greenhouse gases. Thus, reducing the emission of carbon dioxide has become a very important issue around the whole globe recently. However, it is difficult to reduce the amount of carbon dioxide emission dramatically. So, methods to capture and store carbon dioxide in deep sea or underground for long time are suggested. Among these methods, the sequestration of carbon dioxide in coal-beds has been studied by many researchers. Under supercritical condition, carbon dioxide can be sequestrated at 800 m or further below the ground surface. Generally, the temperature and the pressure are reported to increase at the rate of 25 K and 105 bar per km into the ground, respectively. Data measurement for mutual solubilities of water and carbon dioxide are important because water can work as an impurity in carbon dioxide sequestration in coal-beds. Solubility data of carbon dioxide in the water rich phase are abundant in the literature because the measurement techniques are well-established and the measurement is not so difficult. However, in the case of the solubility data for water in carbon dioxide rich phase, deviations among reported data are large because of the difficulties in measurement and uncertainties in analysis methods. In this study, solubilities of water in the carbon dioxide rich phase were obtained by an indirect measurement method. Eight points of experimental data were obtained with uncertainty in composition is 1.0E-4 and uncertainty in temperature is 0.1 K. The measured results were calculated and analyzed using the Cubic-Plus-Association EoS and the Nonrandom Lattice Fluid with Hydrogen Bonding EoS, considering the association of water molecules and the solvation effect between water and carbon dioxide. Both EoS were able to reproduce solutbility data within experimental uncertainty.

Characterization and application of atmospheric pressure microwave plasma for CO2 conversion

Sun, Hojoong Sungkyunkwan university 2021 국내박사

Atmospheric pressure microwave plasmas have been studied plasmas for carbon dioxide conversion. The microwave power was fixed at 2 kW, and the flow rate of carbon dioxide was varied from 5 to 20 slpm. Plasma optical emission spectroscopy (OES) has been conducted to measure ro-vibrational temperatures and electron number densities of the plasma. It is found that the temperatures of the plasmas in carbon dioxide reach 6200 (±200) K at the plasma center by measuring the C2 Swan band spectra and there is little difference between the trans-rotational and vibrational temperatures. The electron number density of the carbon dioxide plasma was deduced by measuring the Stark broadening of the hydrogen Balmer- line shape at 486. 13 nm. The electron number densities of the plasmas were estimated to be approximately 2.06 (±0.12) × 1014 cm-3. Kinetic simulations considering the trans-rotational, vibrational, and electron temperatures separately are also conducted to investigate the details of the plasma decomposition of carbon dioxide. The kinetic simulation demonstrated that the difference between the trans-rotational and vibrational temperatures is negligible, and all the carbon dioxide within the plasma is found to be decomposed into carbon monoxide and atomic oxygen, as a result of the extremely high temperature of the plasma. Thermodynamic-equilibrium calculations indicated that the temperature corresponding to the measured electron density was 6221 (±200) K, which is almost the same as the temperature measured according to the C2 Swan band spectra. From the results, although the electrons in the microwave plasma selectively populate the molecules’ vibrational states, the fast relaxation of these excited vibrational states raises the gas temperature instead of resulting in accumulative vibrational excitation for the efficient dissociation of carbon dioxide and the plasma was in local thermal equilibrium (LTE). As the Application study of atmospheric pressure microwave plasma, dry reforming was conducted on a methane and carbon dioxide mixture, and characterized by measuring the temperature of the plasma and gas composition of the reforming product via OES and gas chromatographic measurement. The temperature at the plasma reached as high as 5900 K, while at microwave power of 2 kW and total flow rate of 10 slpm, nearly all CH4 and CO2 were converted into H2 and CO. The plasma temperature higher than the level achievable from uniform gas heating implied that only a part of the flow will enter the plasma region, and the rest will bypass and mix with the plasma stream at the reactor downstream. Thus, a reactor network-type simulation was carried out by modeling the plasma and surrounding streams each as a series of perfectly-stirred reactors (PSR). The reactors at the same locations interacted for the gas diffusion and heat conduction. The simulation reproduced the experimental results well, revealing that the reforming proceeded as the surrounding gas enters and diffuses out of the plasma stream due to the flow mixing, as well as through the heating of surrounding stream by the plasma stream. 대기압 마이크로웨이브 플라즈마를 이용한 이산화탄소 변환 연구를 수행했다. 마이크로웨이브 출력은 2 kW로 고정했으며, 이산화탄소의 유량은 5 에서 20 slpm으로 변화시켰다. 플라즈마 발광 분광 분석(OES)을 통해 플라즈마의 회전-진동 온도와 전자 밀도를 측정했다. C2 Swan band에서 측정한 플라즈마 중앙의 온도는 6200 (±200) K 였으며, 병진-회전 온도와 진동온도간의 차이는 없었다. 이산화탄소 플라즈마의 전자 밀도는 486.13 nm 파장의 수소 Balmer- 선에 포함된 Stark broadening을 측정해 실험적으로 추론했으며, 전자 밀도는 약 2.06(±0.12)×1014 cm-3로 측정되었다. 플라즈마의 이산화탄소 분해 과정을 밝혀내기 위해 병진-회전, 진동, 그리고 전자 온도를 분리하여 계산하는 수치해석 모델을 개발했다. 수치해석 결과로는, 실험결과와 같이 병진-회전 온도와 진동 온도 간에 차이는 없었으며, 이산화탄소는 플라즈마의 매우 높은 온도로 인하여 플라즈마 내부에서 모두 산소 원자와 일산화탄소로 분해되었다. 열역학적 평형 계산을 통해 실험적으로 측정한 전자 밀도에 해당하는 평형 온도는 OES 측정값과 비슷한 6221 (±200) K 였다. 결과적으로, 마이크로웨이브 플라즈마 내부의 전자는 분자의 진동 상태를 선택적으로 채우지만, 여기 된 진동 상태의 빠른 에너지 전달은 이산화탄소의 효율적인 분해를 위한 누적 여기를 발생시키는 대신 가스의 온도를 상승시키며, 플라즈마는 국부적 열 평형 상태 (LTE)에 도달한다. 대기압 마이크로웨이브 플라즈마를 이용한 응용 연구로 메탄(CH4)의 건식 개질을 진행했으며, OES와 가스 크로마토그래피를 통해 플라즈마의 온도와 개질 가스 조성을 측정했다. 메탄과 이산화탄소 혼합 플라즈마의 온도는 5900 K 였으며, 마이크로웨이브 파워가 2 kW, 총 유량이 10 slpm인 경우 투입 된 메탄과 이산화탄소는 대부분 수소와 일산화탄소로 분해되었다. 또한, 측정된 플라즈마 온도는 투입된 모든 유량에 균일하게 가열한 경우의 온도보다 높게 측정되었는데, 이는 흐름의 일부만 플라즈마 영역으로 들어가고 나머지는 우회한다는 것을 의미한다. 그래서 플라즈마와 주변 흐름을 각각 일련의 perfectly-stirred 반응기(PSR)로 모델링하여 반응기 네트워크 형태의 수치해석 모델을 도출했다. 반응기는 같은 높이에서 가스 확산과 열 전도를 통해 서로 상호작용을 한다. 시뮬레이션 결과는 실험 결과를 잘 재현했으며, 이 결과는 혼합으로 인해 주변 가스가 플라즈마 영역에 들어가고 확산되는 동시에 플라즈마에 의한 주변 흐름의 가열로 개질이 진행되었음을 보여준다.