Chemical and Biological Catalytic Enhancement of Weathering of Silicate Minerals and industrial wastes as a Novel Carbon Capture and Storage Technology

Abstract:

Increasing concentration of CO₂ in the atmosphere is attributed to rising consumption of fossil fuels around the world. The development of solutions to reduce CO₂ emissions to the atmosphere is one of the most urgent needs of today’s society. One of the most stable and long-term solutions for storing CO₂ is via carbon mineralization, where minerals containing metal oxides of Ca or Mg are reacted with CO₂ to produce thermodynamically stable Ca- and Mg-carbonates that are insoluble in water. Carbon mineralization can be carried out in-situ or ex-situ. In the case of in-situ mineralization, the degree of carbonation is thought to be limited by both mineral dissolution and carbonate precipitation reaction kinetics, and must be well understood to predict the ultimate fate of CO₂ within geological reservoirs. While the kinetics of in-situ mineral trapping via carbonation is naturally slow, it can be enhanced at high temperature and high partial pressure of CO₂. The addition of weak organic acids produced from food waste has also been shown to enhance mineral weathering kinetics. In the case of the ex-situ carbon mineralization, the role of these ligand-bearing organic acids can be further amplified for silicate mineral dissolution. Unfortunately, high mineral dissolution rates often lead to the formation of a silica-rich passivation layer on the surface of silicate minerals. Thus, the use of novel solvent mixture that allows chemically catalyzed removal of this passivation layer during enhanced Mg-leaching surface reaction has been proposed and demonstrated. Furthermore, an engineered biological catalyst, carbonic anhydrase, has been developed and evaluated to accelerate the hydration of CO₂, which is another potentially rate-limiting step of the carbonation reaction. The development of these novel catalytic reaction schemes has significantly improved the overall efficiency and sustainability of in-situ and ex-situ mineral carbonation technologies and allowed direct capture and storage of CO₂ from mixture gas streams eliminating the energy-intensive solvent regeneration and CO₂ compression steps.