Optimizing experimental parameters in sequential CO2 mineralization using seawater desalination brine

Abstract

Seawater desalination has two major negative environmental impacts: brine production/discharge and a large carbon footprint arising from energy consumption. Sequential CO2 mineralization is a promising technology to address both issues. This paper reports the effects of key reaction parameters in this process, namely additional agitation of the reactant phases, presence of electrolytes, and CO2 microbubble injection rate. It was found that enhanced mass transport of reactants under agitation and an appropriate CO2 microbubble injection rate are necessary for effective CO2 mineralization by precipitating carbonate minerals. Compared to deionized water, various electrolytes in the brine reduced the amount of CO2 required to achieve the same Mg conversion ratio. However, deionized water led to a much higher purity (98%) of the precipitated hydromagnesite, a valuable product of sequential CO2 mineralization. This report provides useful guidelines for the design of systems for sequential CO2 mineralization with seawater desalination brine.