Enzyme assisted carbon dioxide capture and mineralization in construction relevant alkaline materials

Mineralizing CO₂ in alkaline construction materials can reduce process emissions. This study measures the effect of carbonic anhydrase on CO₂ uptake and retention in hydrated lime, Portland cement, fly ash, and slag under ambient conditions using a mass-flow-controlled CO₂ supply and gravimetric tracking. CO₂ was supplied for 1440 min for hydrated lime and cement and for 360 min for fly ash and slag, then stopped to quantify permanently retained mass. Carbonic anhydrase increased total CO₂ uptake across all materials by 71 to 89 percent. Hydrated lime reached 474.1 mg g^-1 with the enzyme. Cement reached 285.9 mg g^-1. Fly ash and slag reached 308.3 mg g^-1 and 312.4 mg g^-1. The fraction retained after cutoff increased for all solids and was nearly complete in several enzyme cases, while water controls showed negligible permanence. Enzyme reuse over four cycles retained 87.9 percent of the initial performance. The data support a surface-coupled mechanism in which the enzyme accelerates CO₂ hydration in the particle boundary layer, increases local carbonate availability, and drives precipitation with Ca²⁺ and Mg²⁺ on solid surfaces. The reaction endpoint remains unchanged; only the rate is altered. These results define material-enzyme combinations and operating conditions for enzyme-assisted mineralization in construction-relevant systems.