Enzymes and Catalysts for Accelerated Carbonation and Weathering

The slow rate of mineral carbonation is a severe limit to the use of earth materials for controlling carbon dioxide in the atmosphere.  Two chemical reactions are of particular interest: the dissolution of carbon dioxide into water, and the breakdown of silicate mineral matrixes to release divalent cations which can combine with CO2 to form solid carbonates. Two natural enzyme families moderate these reactions in nature.  Carbonic anhydrase is the well-known catalyst for CO2 dissolution, and its importance in biochemistry has encouraged extensive study.  Silicase is a less-studied moderator of the breaking of silica bonds, used by the sponges in managing the growth and destruction of their silica skeletons.  Because silicase has no obvious medical applications, it is poorly studied and the structure has only recently been determined.  It appears to be very similar to carbonic anhydrase, as well as other enzymes active in ester hydrolysis.  We have been evaluating whether the learnings from carbonic anhydrase, particularly synthetic chemical mimics, can be applied to silicase in order to create new means to speed the breakdown of silicate lattices.  The opportunity for a dual-use catalyst family that both encourages CO2 dissolution and silicate breakdown is an attractive possibility, particularly if it can be an inexpensive synthetic. Speeded by catalysts or chemical processes that could significantly speed the rate of mineral carbonation, the intrinsic energy benefit of the mineral carbonation approach could make it a global contributor to managing atmospheric carbon levels.