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Carbon capture and storage is needed to reduce the anthropogenic emissions of carbon dioxide (CO 2 ) in atmosphere. Deep eutectic solvents (DESs), due to their low vapor pressure and environmentally benign nature are possible solvents for the carbon capture step. In the present study, the solubility of CO 2 in three DESs, namely, reline (choline chloride and urea in a 1:2 molar ratio), ethaline (choline chloride and ethylene glycol in a 1:2 molar ratio), and malinine (choline chloride, malic acid, and ethylene glycol in a 1.3:1:2.2 molar ratio) has been studied in a temperature range of (309 to 329) K at pressures up to 160 kPa. Henry's constants for CO 2 −DES systems have been determined under these conditions with values in the range of (3.7 to 6.1) MPa (on a molality basis). Thermodynamic modeling using a modified Peng−Robinson equation of state was used to correlate the experimental data. Results showed excellent agreement with a maximum average absolute relative deviation of 1.6% calculated over the complete set of data. The calculated Gibbs free energy, enthalpy of dissolution, and entropy of dissolution show that the CO 2 absorption is exothermic and the entropy of the system falls as a result of gas absorption.

We examine the hypothesis that selective adsorption to a particular face of ZnO is responsible for the ability of small organic molecules to control the aspect ratio of ZnO crystals during hydrothermal synthesis. Large, single crystals of ZnO were prepared such that the vast majority of a surface consisted of a single crystal plane, as shown by atomic force microscopy, and the adsorption to a single crystal plane was determined by attenuated total reflectance spectroscopy. The results show that citrate strongly and selectively adsorbs to the (0001) face. Similarly, results show that ethylenediamine selectively adsorbs to the (1010) face. Each of these results separately shows a correlation between selective adsorption to and growth of large areas of a particular face, and thus, each result is consistent with the proposed hypothesis.

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Deep eutectic solvents (DESs) are novel solvents that have shown the ability to capture carbon dioxide from flue gases. Thermodynamic modeling is needed to validate the experimental vapor–liquid equilibria (VLE) of the CO2–DES systems. To establish thermodynamic models of these solvents, their critical properties must be estimated. In the present study, a combination of the modified Lydersen–Joback–Reid (LJR) method and the Lee–Kesler mixing rules has been applied to estimate the critical properties of 39 different DESs. Normal boiling temperatures and acentric factors have also been determined. The accuracy of this method has been tested by comparison of theoretical densities determined from the estimated critical properties with experimental values. Absolute deviations ranging from 0 % to 17.4 % were observed for the estimated density values. An overall average absolute deviation of 4.9 % was observed for the studied DESs. Absolute deviations for DESs consisting of aliphatic precursors ranged from 0 % to 9.5 %, whereas for DESs consisting of at least one aromatic precursor, these ranged from 5.8 % to 17.4 %. The accuracy fell as the percentage of hydrogen-bond donors (HBD) increased. The method was also found to accurately take into account the variation in density due to a temperature change.

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A precipitating potassium carbonate (K2CO3)-based solvent absorption process has been developed by the Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) for capturing carbon dioxide (CO2) from industrial sources, such as power plant flue gases. Demonstration of this process is underway using both a laboratory-based pilot plant located at The University of Melbourne and an industrial pilot plant located at the Hazelwood Power Station in Victoria, Australia. The laboratory-scale pilot plant has been designed to capture 4–10 kg/h CO2 from an air/CO2 feed gas rate of 30–55 kg/h. The power-station-based pilot plant has been designed to capture up to 1 tonne/day CO2 from the flue gas of a brown-coal-fired power station. In this paper, results from trials using concentrated potassium carbonate (20–40 wt %) solvent are presented for both pilot plants. Performance data (including pressure drop, holdup, solvent loadings, temperature profile, and CO2 removal efficiency) have been collected from each plant and presented for a range of operating conditions. Plant data for the laboratory-scale pilot plant (including temperature profiles, solvent loadings, and exit gas CO2 concentrations) have been used to validate and further develop Aspen Plus simulations, in anticipation of further work involving precipitation and the industry-based pilot plant.