Investigating the Application of Enzyme Carbonic Anhydrase for CO₂ Sequestration Purposes

Abstract

Biological sequestration of carbon dioxide (CO2) in geological formations is one of the proposed methods to reduce the carbon dioxide released into the atmosphere. In this method, an enzyme is used to enhance the hydration and subsequent precipitation of CO2. In the present work, the effect of bovine carbonic anhydrase on the hydration of CO2, and its precipitation in the form of calcium carbonate, was studied. The enzyme enhanced the hydration reaction. The rate of hydration reaction increased with both the enzyme concentration and temperature. The precipitation of calcium carbonate was promoted in the presence of the enzyme. The concentration of the enzyme did not affect the precipitation; however, temperature impacted the precipitation of calcium carbonate. At higher temperatures, less calcium carbonate was formed. Also, in the presence of the enzyme, calcium carbonate settled more quickly. The enzyme activity was not influenced by the pH of the reaction mixture. In contrast, the formation of calcium carbonate was affected by the pH of the solution. A kinetic analysis was performed for the bovine carbonic anhydrase. Based on the experimental results, the activation energy and catalytic rate constant are estimated as 700.91 cal/mol and 0.65 s-1, respectively.

Effect of Carbonic Anhydrase on CaCO3 Crystallization in Alkaline Solution

“…This is the usual studies in biocatalytic CaCO 3 crystallization at lower pHs as generally reported in the literature. 12,13,34,54,56,57 However, when CA is active at higher pHs and the HCO 3 − ion concentration increases rapidly, the CA now operates in the opposite direction and dehydrates the HCO 3 − ions to produce CO 2 . 46 The CO 2 (aq) can then follow other paths as shown in Figure 4 and end up in CaCO 3 crystallization.…”

Engineered Escherichia coli with Periplasmic Carbonic Anhydrase as a Biocatalyst for CO2Sequestration

“…Although CA accelerates the rate of the CO 2 hydration reaction, it does not affect the equilibrium between the different species of carbonate (43). In a closed system, the final amount of precipitated CaCO 3 does not depend on whether the reaction is catalyzed by CA or not (10,12). Therefore, we focused on the ability of the whole-cell biocatalyst to improve the precipitation (mineralization) rate rather than measure the quantity of the resulting precipitate.…”

“…Purified CA enzymes from natural sources or from recombinant strains have been used in those studies (9)(10)(11)(12)(13). Immobilization techniques to enhance stability and reusability have also been investigated (14,15).…”

Mineral CO2 sequestration by environmental biotechnological processes

“…Lackner et al 1995 introduced a number of chemical and physical methods to increase the rate of the process by accelerating the weathering rate of silicate minerals and precipitation rate of carbonate minerals (Lackner et al, 1995). Application of biological processes has also shown to be a cost-effective approach for accelerating CO 2 sequestration by mineral carbonation (Bennett et al, 2001;Cailleau et al, 2004;Castanier et al, 1999;Huijgen et al, 2003;Mirjafari et al, 2007;Pokrovsky et al, 2009). Four biotechnological processes of: anaerobic digestion (AD), nitrogen removal, desulfurization and bioelectrochemical systems characterized by a sequence of an acid-and an alkalinity-producing steps were specified to be able to adopt the mineral CO 2 sequestration process (Salek et al, 2013b).…”