Using electrochemical process to mineralize CO2 and separate Ca2+/Mg2+ ions from hard water to produce high value-added carbonates

摘要

CO2 mineralization is a promising utilization option for reducing CO2 emissions. Hard water (e.g. seawater, salt water and brine) rich in Ca2+ and Mg2+ ions, has potential for fixation of CO2. But to date there is no effective way to use these ions for CO2 mineralization. In this paper, a novel method based on membrane electrolysis was proposed and used for carbonation and separation of calcium and magnesium ions from hard water in low voltage. Compared with traditional electrolysis, membrane electrolysis can reduce the voltage by about 1.3 V, which reducing the energy consumption for CO2 mineralization dramatically. This method was proved effective to remove the Ca2+/Mg2+ ions from hard water. And CO2 was finally transformed into marketable pure magnesium carbonate and precipitated calcium carbonate. According to this study, 1000 m(3) of concentrated seawater could mineralize 4.65 tons of CO2. In addition, 9.97 tons of magnesium carbonate hydroxide and 2.02 tons of precipitated calcium carbonate could be produced with only a total electric power consumption of 5676 kWh. Therefore, this method affords a new route for CO2 mineralization by transforming hard water into high value-added industrial products with low energy consumption.