ABSTRACT
This chapter highlights the important aspects of lime masonry mortar for the preservation of architectural heritage by looking at the carbonation process by which it hardens, and presents the findings of a bio-inspired approach using carbonic anhydrase enzyme to catalyze lime mortar carbonation. Carbonic anhydrase enzyme (CA) is a particularly efficient biocatalyst that takes part in many processes in living organisms such as respiration, CO2 transport and photosynthesis, promoting the hydration of CO2 and the production of HCO- 3 ions. The pH profiles clearly show that the carbonation reaction proceeds much faster in the presence of CA enzyme at 0.6 M concentration. Interestingly, in the presence of CA enzyme calcite precipitates exclusively as the final CaCO3 phase. In order to understand the kinetic effect that CA enzyme has on phase transformations and final polymorph selection of CaCO3, in-situ experiments were performed on saturated Ca(OH)2 solutions using XRD analysis and micro-Raman.
