Recent progress in microwave characterization of wood based materials has created a need for better understanding of dielectric properties of these materials, which influence the absorption of electromagnetic energy. In the present study the dielectric measurements were carried out for typical Australian wood species such as Slash pine (Pinus elliottii, a softwood species), and Spotted gum (Eucalyptus maculata, a hardwood species), based on Von Hippel's transmission line method. The influence of extractive removal was also studied and compared with the virgin wood samples. Measurements were performed at 9.47 GHz for both virgin and extractive-free wood samples. Experiments were carried out at atmospheric pressure under a range of ambient temperatures between 20 and 25 °C. The dielectric properties of wood species were determined as a function of controlling factors such as density, moisture content, and fiber directions. Moisture content varied from 0% to 13% for virgin wood samples at atmospheric equilibrium conditions. Results indicated that the dielectric properties of both wood species were affected by density, moisture content, and fiber directions. In general, for virgin wood samples, the dielectric property was found to increase with density and moisture content. The values of the dielectric property in parallel direction to the stem were generally higher than those in the perpendicular direction for virgin sample of both wood species. However, such a trend was not observed for extractive-free wood samples.

Recent interest in sequestration of carbon dioxide (CO 2 ) in gasified coal seam (i.e., post-underground coal gasification sites) has created a need to understand the coal properties, specifically, the adsorption behavior of CO 2 on gasified coal. In the present study, the CO 2 excess adsorption isotherms were determined for four coal samples of different characteristics based on the volumetric method. Further, coal chars from a coking coal and a non-coking coal (within the studied samples) were investigated for their CO 2 adsorption capacity. The coal samples of size 22−32 mm were pyrolyzed in a drop-tube furnace at 800 and 1000 °C with a heating rate of approximately 2.5 °C s −1 under an inert atmosphere. Measurements were performed up to a pressure of 65 bar for all of the studied samples. Experiments were carried out at an isothermal temperature of 45.5 °C. The influence of coal properties on adsorption was also studied and compared to the literature data. Behavior of adsorption capacities was analyzed as a function of coal properties, such as vitrinite content, coal rank, volatile matter, ash content, and surface area. Results indicated that the adsorption capacity of coal char is much higher in comparison to the virgin coal samples. It was understood from the surface area analysis that there is a significant increase in surface area when coal is pyrolyzed. In addition, for coal samples, the trend of adsorption isotherms was in good agreement with the literature data.

Post-underground coal gasification (UCG) sites hold attractive prospects for geological storage of carbon dioxide. For the successful commercial implementation of UCG with carbon capture and storage (CCS), site-selection is crucial, and a careful techno-economic feasibility analysis is essential to systematically assess the site related parameters aside from evaluating the environmental risk. This study is related to one of the important aspects of site selection-the coal type. Specifically, this work investigates the influence of coal properties and gasification conditions on the adsorption capacities of CO 2 on gasified coal chars. For this purpose, four coals of diverse ranks varying from lignite to bituminous were selected and subjected to CO 2 gasification at atmospheric pressure for 10 min at 800, 900, and 1000°C under a low heating rate of 5°C/min. Subsequently, the gasified chars, as well as the raw coals, were tested for their adsorption capacity in a purpose built volumetric adsorption apparatus at 45.5°C and pressures up to 90 bar. Also, complementary coal and char analysis were carried out for determining the surface area, pore size distribution, and surface morphology. The CO 2 storage capacity was observed to be a strong function of the coal properties and gasification conditions. Among the samples examined, the highest adsorption capacity was observed for chars of the sub-bituminous coals. The CO 2 adsorption capacity at 80 bar and 45.5°C on the sub-bituminous char samples was 2.08, 2.43, and 1.95 mmole/g that were prepared at 800, 900, and 1000°C, respectively. The experimental adsorption isotherms were fitted to the Dubinin-Radushkevic (DR) and the Dubinin-Astakhov (DA) models. 322

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