The Electrolyte Nonrandom Two-Liquid Activity Coefficient model in Aspen PlusTM 2006.5 was used to develop a rigorous and consistent thermodynamic representation for the base sub-component systems associated with aqueous combinations of K₂CO₃, KHCO₃, MEA, and piperazine (PZ) in a mixed-solvent electrolyte system for the application of CO₂ absorption/stripping from coal fired power plants. We developed a new vapor-liquid equilibrium apparatus to measure CO₂, amine, and H2O vapor pressures at 40 and 60 oC. We found that the volatility of MEA and PZ can be approximated at 50 and 20 ppmv at 40°C for any solvent composition studied in this work, over the CO₂ partial pressure range from 0.01 to 0.1 kPa. Very few solvent compositions exhibited a greater differential capacity than 7 m MEA at 60°C; specifically 11 m MEA, 3.5 m MEA + 3.6 m PZ, 7 m MEA + 2 m PZ, 7 m MEA + 3.6 m PZ, and 5 m K+ + 7 m MEA + 3.6 m PZ. Piperazine exhibited a possible maximum differential capacity of 2.21 mole CO₂/kg-H₂O at a concentration of 7.3 m. At the Norwegian University of Science and Technology, Inna Kim determined the differential enthalpy of CO₂ absorption for aqueous combinations of K₂CO₃, KHCO₃, MEA, PZ, and CO₂, based on a consistent experimental method developed for MEA, from 40 to 120°C for use in this work. In addition, we developed a consistent method to measure the specific heat capacity for a number of similar solvent combinations. We found that the enthalpy of CO₂ absorption increased with temperature because the apparent partial heat capacity of CO₂ may be considered small. Finally, by using a differential scanning calorimeter, we determined the dissolution temperature for aqueous mixtures of unloaded piperazine, which inferred an effective operating range for solutions of concentrated piperazine, greater than 5 m PZ, over a loading range between 0.25 to 0.45 mole CO₂/2·mol PZ. Through unit cell x-ray diffraction, we were able to identify and characterize the presence of three solid phases (PZ·6H₂O, KHCO₃, and KvPZ(COO)₂) in aqueous mixture combinations of K₂CO₃, KHCO₃, PZ, and CO₂. / text

No description available.

No description available.

Thesis (M.E.S.)--The Evergreen State College, 2007. / Title from title screen viewed (2/14/2008). Includes bibliographical references (leaves 34-40).

Thesis (M.S.)--Ohio University, August, 2000. / Title from PDF t.p.

Thesis (Ph. D.). University of Lund. Depts. of Anasthesia and Clinical Physiology.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering September, 2017 / South Africa emits large amounts of carbon dioxide (CO2) due to its reliance on coal. The emission of CO2 needs to be reduced for clean sustainable energy generation. Research efforts have therefore been devoted to reducing CO2 emissions by developing cost-effective methods for capturing and storing it. Amine-based absorption using monoethanolamine solvent is the most mature technique for CO2 capture despite its huge energy consumption, corrosiveness and difficulty in solvent regeneration. However, CO2 removal by solid adsorbents is a promising alternative because it consumes less energy, and can be operated at moderate temperature and pressure. Metal organic frameworks have received attention as a CO2 adsorbent because they have large surface areas, open metal sites, high porosity and they require less energy for regeneration. This research was aimed at optimizing and scaling-up SOD-ZMOF through structural modification for enhanced CO2 adsorption by impregnating it with chitosan. Scaled-up SOD-ZMOF samples were prepared as described elsewhere and impregnated with Chitosan. Physiochemical properties obtained using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Nitrogen physisorption showed that SOD-ZMOF and SOD-ZMOF-chitosan were successfully synthesized. Qualitatively, the surface area of the SOD-ZMOF synthesized using the scaled up protocol is lower than the one prepared using the non-scaled-up protocol XRD pattern of SOD-ZMOF showed that it was crystalline and was in agreement with literature. The XRD peaks of the SOD-ZMOF decreased after chitosan impregnation showing that chitosan was impregnated on SOD-ZMOF. The FTIR spectrum of SOD-ZMOF showed functional groups present in organic linker used to synthesize SOD-ZMOF, and that of the SOD-ZMOF-chitosan revealed the same functional groups but with disappearance of carboxylic acid functional group. N2 physisorption showed a decrease in BET surface area and pore volume after chitosan impregnation on SOD-ZMOF as well. Performance evaluation of the material was carried out with a demonstration adsorption set-up using a 15%/85% CO2/N2 mixture and as a thermal gravimetric analysis (TGA) using 100% CO2. For both the packed-bed column and the TGA experiments, evaluation was conducted on SOD-ZMOF and SOD-ZMOF with chitosan for comparison. About 50 mg of the adsorbent was used at 25 oC, 1 bar and 25 ml/min for the packed-bed column. For the adsorption with the TGA, 11 mg of adsorbent was used at 25 ℃, 1 bar and 60 ml/min. SOD-ZMOF showed improved adsorption capacity after chitosan impregnation. CO2 adsorption capacity of SOD-ZMOF increased by 16% and 39% using packed-bed column and TGA, respectively, after chitosan impregnation. The increase in adsorption capacity was attributed to the impregnated chitosan that has amine groups that display a high affinity for CO2. A traditional approach was used to investigate the effect of adsorption temperature and inlet gas flowrate on the CO2 adsorption capacity of SOD-ZMOF-chitosan. This was done using both the parked bed column and the TGA. Temperature range of 25-80 ℃ and inlet gas flowrate range of 25-90 ml/min were investigated. Adsorption capacity increased with a decrease in temperature and inlet gas flowrate. For the packed-bed column, maximum of 781 mg CO2/ g adsorbent was obtained at 25℃, 1 bar, 25 ml/min and for the TGA a maximum CO2 adsorption capacity of 23 mg/ g adsorbent at 25 ℃, 1 bar, and 60 ml/min was obtained. / MT2018

No description available.

The consumption of large quantities of fossil fuels on a yearly basis for energy purposes has led to the release of vast quantities of carbon dioxide into the Earth s atmosphere leading to global warming. In order to decrease the amount of carbon dioxide entering the atmosphere, procedures such as carbon dioxide capture and storage are currently being implemented, although this process is successful in decreasing atmospheric carbon dioxide concentration it results in the mindless storage of an otherwise synthetically useful reagent. The development of a viable method to capture carbon dioxide, followed by synthetic utilisation often referred to as CCU is currently gaining much attention. The main challenges in the development of a suitable utilisation reaction are energy and cost efficiency as well as the use of environmentally friendly conditions. Previous reports on utilisation include the catalytic incorporation of carbon dioxide into epoxides under electrochemical conditions, however this process had several drawbacks. In this project the shortcomings of this reported procedure have been addressed in order to develop a potentially viable utilisation process. The catalyst free electrocarboxylation of mono-substituted epoxides, using a magnesium anode/copper cathode electrode couple and tetrabutylammonium bromide supporting electrolyte in a sealed single compartment cell, was achieved under mild reaction conditions (1 atmosphere carbon dioxide pressure, 60 milliamperes constant current and 50 degree celsius heating), producing the corresponding 5-membered cyclic carbonate product in excellent yields (65-96%). Interestingly the use of sono-electrolysis allowed the reduction of para-substituted aromatic epoxides. The stoichiometric addition of tetrabutylammonium bromide was key for the effective activation of carbon dioxide and the epoxide. Similar carbon dioxide incorporation into analogous mono-substituted aziridines, synthesised using a modified Wenker synthesis allowed the formation of the corresponding cyclic carbamates in moderate to excellent yields (32-90%). The selective synthesis of 6-membered cyclic carbonates from oxetane substrates was also achieved in good yields (60-70%) as well the non-selective synthesis of polytrimethylene oxide. The electrochemical process also allowed the tandem formation of magnesium carbonate in quantitative yield (85%). Furthermore substrate free electrocarboxylation allowed the synthesis of alternative iron and zinc carbonates in excellent yield (83-85%) as well as the selective synthesis of aluminium oxalate (99%). Coupled with the high recovery of the supporting electrolyte (90%), this work has demonstrated the economical synthesis of industrially useful chemical feed-stocks under green conditions.

Microbial decomposition of soil organic matter (SOM) releases around 98 Pg of C (as CO2) to the atmosphere annually. Quantifying CO2 emissions from SOM is necessary to monitor and manage them but is complicated by proximate respiration of CO2 from plant roots, and by the influence of roots on SOM decomposition rate. Differences in the natural abundance of 13C in root and SOM-derived respiration (of < 10 ‰ in most temperate ecosystems) can be used to apportion their contributions to soil-surface CO2 efflux. However, this is challenging because all three δ13CO2 measurements are susceptible to significant sampling errors, which this study set out to identify and resolve, as follows. Respired CO2 sampled from excised roots is 13C-depleted by 1.8 ‰ (± 0.47) compared to intact roots due to the contribution of CO2 from root wounds. Root-respired δ13CO2 is more reliably measured using chambers around live, intact roots. These chambers also permit detection of diurnal changes in root-respired δ13CO2. Soil disturbance during sampling and root removal changes the carbon substrates available to microbes and this is reflected in a rapid (1-2 hours) decrease in δ13C of respiration of c. 4 ‰. This change can be regressed to estimate the δ13CO2 of microbial respiration from undisturbed soil. Techniques for measuring soil-surface efflux δ13CO2 induce method-specific biases of as much as 5 ‰, as measured in intact mesocosm soil and when simulated using a numerical diffusion model. Discrepancies between measurements and model predictions may be due to complexities of gas transport not currently accommodated in diffusion models, namely, near-surface advection and non-uniform soil diffusivity. Using improved techniques, this study used natural abundance 13C partitioning to assess priming effects, identify distinct environmental drivers of root-respired and SOM-derived CO2 fluxes, and detect differences in soil carbon cycling between tree species, possibly attributable to mycorrhizal type.