Energizing the CO2 utilization by chemo-enzymatic approaches and potentiality of carbonic anhydrases: A review

Abstract During the last few decades, enormous emissions of greenhouse gases (GHGs) into the atmosphere by human activities, lead to global warming. Thus, it becomes essential to prevent the excessive emission or to develop new technologies to avoid successive accumulation of CO2. Biological systems in nature have the capability to fix the atmospheric CO2 but in the urban and industrially developed areas where a rate of CO2 emission is very high, the biological system cannot capture and utilize the whole CO2. Various chemicals and synthetic materials with CO2 absorbing property are not eco-friendly or these are very expensive. Carbonic anhydrase (CA) is the fastest known enzymes containing zinc in its active site, convert CO2 to bicarbonate ions. It is one of a potent biological catalyst for CO2 conversion. Thus, in order to reduce the level of CO2 the biocatalytic properties of microbial CA can be exploited. Literature survey showed that, more than fifty different microbial CAs have been explored for CO2 sequestration. The major advantages of CA to sequester CO2 are economic viability and carbonation of CO2 at a low concentration. Despite the higher rate of catalysis, the stability of CA is a major challenge for its industrial application. These difficulties have been partly solved by immobilizing the CA onto the bio-inspired surface, biochar, alginate, polyurethane foam and variety of nano-textured materials. A combination of enzyme and material which jointly capture and convert the CO2 into either carbon-rich compound of economic value or reduced carbon derivatives will plausibly energize the CO2 utilization. In this review, we discussed the recent advances in chemical and materials used for CO2 capture, their advantages and limitations, utilization of microbial CA for CO2 conversion, and its various applications.