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A novel CO2 sequestration concept is reported that combines SO2 removal and CO2 capture and sequestration, using a bauxite-processing residue which is a waste product and with waste brine water from oil/gas production. The bauxite residue/brine mixture of 46/54 v/v exhibited a CO2 sequestration capacity of > 0.078 mol L–1 when exposed to pure CO2 at 20 °C and 2.73 MPa. At a higher temperature of 140 °C, a bauxite residue/brine mixture of 80/20 v/v indicated a CO2 sequestration capacity of > 0.094 mol L–1 when exposed to pure CO2 at 3.85 MPa. Under the same reaction conditions, an identical ratio of reaction mixture exposed to simulated flue gas at a similar initial pressure was capable of sequestering 0.16 mol of CO2 and > 99.9 % of the applied SO2. Calcite formation was verified as a product of bauxite/brine mixture carbonation. The caustic bauxite residues (pH 12.5–13.5) and acidic wastewater brine (pH 3–5) are also effectively neutralized after participating as reactive reagents in the conceptual process.

A combination of mechanical sieving and triboelectrostatic separation were used to separate fly ash. The results indicate that a simple separation of unburned carbon from fly ash is achievable at particle sizes of 74 and 44 microns. Subsequently, triboelectrostatic separations were conducted via a louvered plate separator. The results show that the final carbon content in the products, which can be as low as 1.5 % or as high as 60 % with different mineral components, can be further adjusted with the combination of sieving, louvered plate separator with a tribocharger made of different materials (copper and Teflon), and the location on the louvered plate where the fly ash particles were collected.

Many types of materials e.g., rubber, polymer, coal, change their volume and structure after absorption of gaseous and liquid substances. Various kinds of volume changes affect the accuracy of absorption measurements by gravimetric and manometric methods, the two major techniques currently employed. The errors associated with the volumetric effects, specifically, the case of carbon dioxide sorption on coal, were investigated. It was demonstrated that the resulting error in the buoyancy correction in the gravimetric method is equivalent to the corresponding error in the assumed void volume in the manometric method. It is suggested that the integration of the two methods, combined with the binary gas mixture technique of in-situ volume measurement, will contribute to dramatically improve the accuracy of absorption measurements for plastic materials.

An ultrasonic transmission technique is under development to determine the concentration of solids in a three-phase slurry reactor by measuring the velocity of ultrasound in slurries. Preliminary measurements have been made on slurries consisting of water, glass beads, and air bubbles. The data show that both the sound speed and attenuation are well-defined functions of both the solid and gas concentrations in the slurries. A simple model is proposed to correlate the concentration of solids with the measured ultrasonic signals.

An ultrasonic transmission technique has been developed to measure solids holdup in a gas-liquid-solid bubble column reactor. The results presented in this study show that the transit time of an ultrasonic signal is influenced by the variation of solids holdup and the operating conditions in the bubble column. The transit time can be correlated to the solids holdup. The ultrasonic technique is potentially applicable to high-temperature, nontransparent fluids in high-pressure, metallic reactors and, with some modifications for solids holdup measurements, applicable in slurry-bubble column reactors.