Sustainable carbon-negative mineral extraction from desalination brine

Abstract

Effective brine management requires an economical and sustainable methodology to treat multiple pollutants in a single reaction and recover valuable resources like fresh water and minerals. Herein, we propose a novel one-pot solution that employs electrochemical oxygen reduction reaction (ORR)-generated hydroxide (OH-) to recover valuable minerals from seawater reverse osmosis brine and capture CO2. The process efficiently extracts and recovers magnesium (Mg2+) and calcium (Ca2+) ions in the form of marketable compounds such as CaCO3, Mg(OH)2, or MgCO3, using commercially available catalysts. Our results indicate that the proposed system achieves efficient mineral recovery, reaching up to 27.7 % for Mg2+ and 63.7 % for Ca2+ at a cell current of 60 mA within 8 h. Notably, approximately 40 % of the obtained minerals exist in carbonate form, highlighting the successful mineralization and carbonization of the waste stream into valuable compounds. Moreover, it reduced energy consumption by up to 30 % compared to traditional methods. Initial technology economic analysis confirms that the proposed novel process is carbon-negative and profitable. This cutting-edge and economically competitive ORR-based system technology combines minerals recovery, carbon abatement, and wastewater stream treatment, advancing decarbonization efforts and delivering global environmental benefits, providing an alternative approach for sustainable carbon-negative mineral extraction.