Review of the Application of Hydrotalcite as CO2 Sinks for Climate Change Mitigation

In recent decades, the environmental impact caused by greenhouse gases, especially CO2, has driven many countries to reduce the concentration of these gases. The study and development of new designs that maximise the efficiency of CO2 capture continue to be topical. This paper presents a review of the application of hydrotalcites as CO2 sinks. There are several parameters that can make hydrotalcites suitable for use as CO2 sinks. The first question is the use of calcined or uncalcined hydrotalcite as well as the temperature at which it is calcined, since the calcination conditions (temperature, rate and duration) are important parameters determining structure recovery. Other aspects were also analysed: (i) the influence of the pH of the synthesis; (ii) the molar ratio of its main elements; (iii) ways to increase the specific area of hydrotalcites; (iv) pressure, temperature, humidity and time in CO2 absorption; and (v) combined use of hydrotalcites and cement-based materials. A summary of the results obtained so far in terms of CO2 capture with the parameters described above is presented. This work can be used as a guide to address CO2 capture with hydrotalcites by showing where the information gaps are and where researchers should apply their efforts.