Efficient magnesium recovery from seawater desalination brine via CO2 mineralization to synthesize hydromagnesite for uranium extraction

Abstract

Magnesium (Mg2+) is the most abundant resource in the seawater desalination brine. The efficient and economical extraction of Mg2+ is crucial for recovery of other ions. In this work, we proposed a facile and cost-effective method to completely transform Mg2+ to hydromagnesite via carbon dioxide (CO2) mineralization. The effects of the injection time of CO2, concentration of sodium hydroxide solution, reaction temperature, and aging time on the synthesis of hydromagnesite and utilization ratios of Mg2+ and CO2 were investigated. The synthesized hydromagnesite exhibited flower-like spherical morphology, and the utilization ratios of Mg2+ and CO2 could reach 99.91 % and 87.75 %, respectively. The formation process of hydromagnesite was illustrated by the time-dependent experiment. The synthesized hydromagnesite was applied to the uranium extraction with the coinstantaneous high maximum adsorption capacity and adsorption efficiency. Especially, it could exhibit good selectivity with the adsorption capacity of 0.32 mg·g−1 and adsorption efficiency of approaching 90 % in 5 L of natural seawater for 10 days. The cycling experiments suggested that the synthesized hydromagnesite possessed the good stability. Therefore, the recovery of Mg2+ to synthesize hydromagnesite via CO2 mineralization is a high-efficiency and low-cost method; meanwhile, the synthesized hydromagnesite shows promising application prospects in the uranium extraction.