CO2 Mineralization Using Brine Discharged from a Seawater Desalination Plant

Abstract

CO 2 mineralization is a method of sequestering CO 2 in the form of carbonated minerals. Brine discharged from seawater desalination is a potential source of Mg and Ca, which can precipitate CO 2 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 CO 2 mineralization that involves an increase in the pH of the brine, followed by CO 2 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 CO 2 mineralization. The resulting precipitates were CaCO 3 (calcite), Mg 5 (CO 3 ) 4 (OH) 2 ·4H 2 O (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 CO 2 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 CO 2 mineralization.

The significant role of pH in pretreatment of SWRO Plant for renewable water source

“…Bang, et al 19 treated the feed water with CO2 at alkaline pH, where the pH of solution was elevated to 10 with the help of NaOH. The bubble of CO2 through injection was introduced into the solution which turned into CO3 -2 and formed white precipitates of calcium and magnesium carbonates.…”

Study of the Effect of Leucine on Calcium Carbonate Precipitation in a Circular Economy Perspective

“…An industrial example is the postdistillation liquid from the Solvay Process (production of sodium carbonate, soda-ash), that is a Ca-rich waste [9]; if not correctly disposed of, this waste is responsible for the strong salinity of nearby groundwater with calcium chloride pollution of natural water reservoirs and soil [10]. Instead, this liquid waste can be used for CaCO 3 precipitation with CO 2 utilization [11]. Other examples of wastes that can be used to produce calcium carbonate via carbonation are paper sludge ash from paper manufacturing and oil shale ash [10] and desalination brines.…”

Enhanced precipitation of magnesium carbonates using carbonic anhydrase

“…12 To offset this cost several authors have proposed alternative sources of alkalinity, which are more reactive, such as industrial waste, mine tailing, and brines (including salt lake brines, mine drainage, seawater, and desalination brines). [13][14][15][16][17][18] With these alternative sources CO 2 mineralization can be carried out at low temperatures and low p CO 2 . Brines are particularly interesting because alkaline earth elements (e.g., Ca, Mg, and Na) are readily accessible for precipitation.…”