Abstract
The unprecedently high CO2 levels in the atmosphere evoke the urgent need for development of technologies for mitigation of its emissions. Among the alternatives, the biocatalytic route has been claimed as one of the most promising. In the present work, the carbonic anhydrase from bovine erythrocytes (BCA) was employed as a model enzyme for structural studies in an aqueous phase at alkaline pH, which is typical of large-scale absorption processes under operation. Circular dichroism (CD) analysis revealed a high enzymatic stability at pH 10 with a prominent decrease of the melting temperature above this value. The CO2 absorption capacity of the aqueous solutions were assessed by online monitoring of pressure decay in a stainless-steel cell, which indicated a better performance at pH 10 with a kinetic rate increase of up to 43%, as compared to non-biocatalytic conditions. Even low enzyme concentrations (0.2 mg g−1) proved to be sufficient to improve the overall CO2 capture process performance. The enzyme-enhanced approach of CO2 capture presents a high potential and should be further studied.
Highlights
The impact on the planet and on society caused by the increasing emission of greenhouse gases to the atmosphere has raised the urgent need for development of technologies for mitigating gas emissions and their capture
The mineral water (MW) used in the work was characterized according to its ionic composition (Table 1)
Structural studies on the BCA under industrially relevant aqueous conditions for CO2 capture suggest that the enzyme changes its conformation at temperatures of 61–72 ◦C, which are lower than typical stripping stages, which evidences the need to adopt stabilization approaches for further implementation of processes using this enzyme
Summary
The impact on the planet and on society caused by the increasing emission of greenhouse gases to the atmosphere has raised the urgent need for development of technologies for mitigating gas emissions and their capture. CA catalyzes the reversible reaction that involves the hydration of CO2 to bicarbonate with concomitant release of protons (Reaction (R1)) and with an unprecedently high reaction rate (kcat ≈ 106 s−1) [5] This kinetic potential, as well as the ubiquitous occurrence of CAs in nature [6], entitle this enzyme as a good biocatalyst for industrial applications, such as CO2 capture from air, post-combustion, biogas, and natural gas streams [3,7]. From this group, the CA from bovine erythrocytes (BCA) has been one of the most studied due to its activity under a wide pH range and commercial availability [8,9], among other interesting properties
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