Ionic liquids (ILs) are being considered as solvents for gas absorption processes as they have the potential, in general, for improved efficiency of gas separations, as well as lower capital and operating costs compared to current commercial processes. In this study the solvent properties of ILs are investigated for use in the absorption of carbon dioxide (CO2) and oxygen (O2). The absorption of these gases in ILs was measured in the temperature range 303.15-333.15 K and at pressures up to 1.5 MPa by gravimetric analysis. The ILs used were methyl trioctyl ammonium bis (trifluoromethylsulfonyl) imide ([MOA][Tf2N]), 1-butyl-3-methyl imidazolium bis (trifluoromethylsulfonyl) imide ([BMIM][Tf2N]), and 1-butyl-3-methyl imidazolium methyl sulfate ([BMIM][MeSO4]). The measurement technique employed in this study is fast and accurate, and requires small quantities of solvent. The results indicated that absorption of both gases increased with a decrease in operating temperature and an increase in pressure. [MOA][Tf2N] had the highest CO2 and O2 solubility. [BMIM][Tf2N] was determined to have the highest selectivity for CO2 absorption. [BMIM][MeSO4] achieved the lowest CO2 absorption with a moderate O2 absorption, revealing this IL to be the least desirable for CO2 and O2 absorption. Calculation of Henry's law constants for all systems confirmed the deductions made from absorption data analysis. Calculation of enthalpy and entropy of absorption for each system revealed CO2 absorption in [MOA][Tf2N] to be the least sensitive to temperature increases. The absorption data was modeled using the generic Redlich-Kwong cubic equation of state (RK-EOS) coupled with a group contribution method.

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Carbon dioxide (CO 2) emissions and their association with climate change are currently a major discussion point in government and amongst the public at large in South Africa, especially because of the country's heavy reliance on fossil fuels for electricity production. Here we review the current situation regarding CO 2 emissions in the South African power generation sector, and potential process engineering solutions to reduce these emissions. Estimates of CO 2 emissions are presented, with the main sources of emissions identified and benchmarked to other countries. A promising mid-term solution for mitigation of high CO 2 emissions, known as CO 2 capture and storage, is reviewed. The various aspects of CO 2 capture and storage technology and techniques for CO 2 capture from pulverised coal power plants are discussed; these techniques include processes such as gas absorption, hydrate formation, cryogenic separation, membrane usage, sorbent usage, enzyme-based systems and metal organic frameworks. The latest power plant designs which optimise CO 2 capture are also discussed and include integrated gasification combined cycle, oxy-fuel combustion, integrated gasification steam cycle and chemical looping combustion. Each CO 2 capture technique and plant modification is presented in terms of the conceptual idea, the advantages and disadvantages, and the extent of development and applicability in a South African context. Lastly, CO 2 transportation, storage, and potential uses are also presented. The main conclusions of this review are that gas absorption using solvents is currently most applicable for CO 2 capture and that enhanced coal bed methane recovery could provide the best disposal route for CO 2 emissions mitigation in South Africa.

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Access to clean, reliable water services is not a guarantee for all U.S. communities. The challenges related to such service failures have inequitable impacts on low-income neighborhoods and communities of color. How equity is defined and operationalized in water-sector infrastructure is inconsistent across the literature and in practice. This inconsistency can make it challenging to hold utilities accountable for unequal distributions of burden (e.g., lack of affordability and poor water quality). As such, this study seeks (1) to determine how equity is currently defined and used in the water sector, (2) to develop a definition that can be used to incorporate equity into water-sector infrastructure, and (3) to understand attitudes toward equity of water-sector professionals. We conduct a qualitative analysis of relevant media articles, survey responses, and semi-structured interviews with water-sector professionals. We propose a definition of equity in water that is informed by the results of this analysis. Categories emerge that can be leveraged to create vertical equity solutions, such as addressing intermittent supply and water-quality issues in vulnerable communities. The definition may be used to operationalize, metricize, and benchmark equitable water policy and practices at all levels of decision making (e.g., federal, state, and local) to ensure an equitable water future.

International audienceThis report contains CO2 loading data for the solvent absorption of CO2. Two amine blends were studied extensively using a static analytic apparatus described herein. The blends were 25 wt% MDEA-25 wt% DEA-50wt% H2O and 30 wt% MDEA-20 wt% DEA-50 wt% H2O. A minor study was conducted on a 50 wt% DEA-50 wt% H2O solvent as well. Different CO2 partial pressures were studied, ranging from 0.05 to 1.05 MPa. Nitrogen gas was used for achieving desired system pressure. System pressures ranged from 0.5 to 1.5 MPa. Solvent absorption was studied at 363.15 and 413.15 K. The data is presented and discussed in this report, both tabulated, as solubility curves and partition coefficient curves. Conclusions drawn from the CO2 liquid loading data are that increasing temperature greatly reduces the absorption capacity of the solvents studied. The amine blend of 25 wt% MDEA-25 wt% DEA-50 wt% H2O produced the best loading performance of all the solvents studied, as well as the literature data that was used for comparison. This proved that higher concentrations of DEA in the blend, is beneficial in increasing CO2 liquid loading in relation to CO2 partial pressure. The data was also compared to similar systems in literature, as well as in terms of partition coefficients, showing some contradictory and varying results. The literature data found also varied among sources. A wider and more standardised method of experimentation is required to confirm the results

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