Abstract
CO2 mineralization is a method of sequestering CO2 in the form of carbonated minerals. Brine discharged from seawater desalination is a potential source of Mg and Ca, which can precipitate CO2 as forms of their carbonate minerals. The concentration of Mg and Ca in brine are twice those in the seawater influent to desalination process. This study used a cycle for CO2 mineralization that involves an increase in the pH of the brine, followed by CO2 bubbling, and, finally, filtration. To the best of our knowledge, this is the first time that non-synthesized brine from a seawater desalination plant has been used for CO2 mineralization. The resulting precipitates were CaCO3 (calcite), Mg5(CO3)4(OH)2·4H2O (hydromagnesite), and NaCl (halite) with these materials being identified by X-ray Diffraction (XRD), Fourier transform infrared (FTIR) and thermo gravimetric-differentail thermal Analysis (TGA)-DTA. Despite the presence of Ca with Mg in brine being unfavorable for the precipitation of Mg carbonate, Mg reacted with CO2 to form hydromagnesite at a yield of 86%. Most of the Ca formed calcite, at 99% yield. This study empirically demonstrates that brine from seawater desalination plants can be used for CO2 mineralization.
Highlights
Climate change and abnormal weather phenomena have been worsening, owing to increasedCO2 emissions around the world
Seawater desalination processes remove the salts from seawater by distillation, membrane separation, and/or reverse osmosis (RO) to produce useful water that is suitable for drinking and industrial purposes [3,4,5]
This paper introduces the first use of non-synthesized brine discharged from a functional seawater desalination plant for CO2 mineralization; we have focused on the precipitation of
Summary
Climate change and abnormal weather phenomena have been worsening, owing to increased. Seawater desalination processes remove the salts from seawater by distillation, membrane separation, and/or reverse osmosis (RO) to produce useful water that is suitable for drinking and industrial purposes [3,4,5]. Owing to the significantly higher concentration of Mg than Ca in seawater and brine, Mg would allow much more CO2 mineralization than Ca does This does not necessarily mean that more precipitating Mg carbonates than Ca carbonates will be produced, because Ca carbonates are more sparingly soluble than Mg carbonates (for example, Ksp (hydromagnesite) = 1.26 × 10−5 [24], and Ksp (calcite) = 3.36 × 10−9 at 25 ◦ C each [25]). We have empirically proved that CO2 mineralization using brine for CO2 sequestration
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