Enhancing serpentine dissolution kinetics for mineral carbon dioxide sequestration

Abstract

Mineral carbon dioxide sequestration binds carbon dioxide by reacting it with magnesium silicate minerals to form solid magnesium carbonates that are ready for disposal. Research on mineral sequestration has focused on enhancing process kinetics in aqueous processing schemes. High costs of these processes are associated with mineral processing, such as ultrafine grinding, or the consumption of acids and bases, which are required to speed up silicate mineral dissolution kinetics. Neutral organic salts such as sodium oxalate, and citrate enhance dissolution kinetics of serpentine in the circum-neutral pH range appropriate for mineral carbonate precipitation and have potential for use in an enhanced carbonation process. Concentration and temperature dependencies for the dissolution of antigorite serpentine in the presence of the citrate ion are experimentally derived under weakly acidic conditions. Rates are shown to be several orders of magnitude higher in the presence of citrate than in the weakly acidic solution alone.