Investigation on the Immobilization of Carbonic Anhydrase and the Catalytic Absorption of Carbon Dioxide

Abstract

The optimum conditions, such as pH, immobilization time, temperature, and enzyme dose, for carbonic anhydrase (CA) immobilized on the polyester polyurethane prepolymer 80 were investigated. Simultaneously, the performances (e.g., pH, thermal, operational, and storage stabilities) of immobilized CA and free CA were compared. The results revealed that the optimum conditions, such as pH value of Tris−HCl buffer, immobilization time, temperature, and enzyme dose, of immobilized CA were 7.5, 24 h, 35 °C, and 1 mL of enzyme solution (0.1 mg/mL)/0.1 g of polyester 80, respectively. Moreover, pH and operational, thermal, and storage stabilities of immobilized CA were higher than those of free CA. On this basis, the experiment was conducted to immobilize CA to absorb CO 2 . The results indicated that the CO 2 concentration, liquid/gas ratio, and gas flow rate may affect the properties of CO 2 absorption. The CO 2 absorption efficiency dropped from 63 to 42.7% with an increase in the CO 2 concentration from 9 to 15.4%. With the increase of the gas flow rate, the CO 2 absorption efficiency first increased and subsequently decreased. The absorption efficiency increased from 30.9 to 57.7% with an increase in the liquid/gas ratio from 26 to 34 L/m 3 . The optimal operating conditions can accelerate the absorption rate of CO 2 and reduce the usage of immobilized CA, which can reduce the cost of CO 2 sequestration.

Lag Time Spectrophotometric Assay for Studying Transport Limitation in Immobilized Enzymes

“… 13 This effect might facilitate the fixation of carbon dioxide inside the hydrogel, by removing the obtained protons and maintaining the optimal environment for CA, which has been reported as slightly alkaline for immobilized CA. 6 On the contrary, TBAB-Nafion does not present the “proton pump effect”; thus, an increased concentration of protons inside the layer might decrease the pH locally and inhibit the activity of CA. Mag-EPC-immobilized CA showed a considerable loss of activity; however, a lag time similar to the free enzyme in solution was obtained.…”

“…Immobilization techniques have been shown to greatly increase the stability and lengthen the half-life of different enzymes, 5 including CA. 6 However, performance can be strongly affected by transport limitations because of the very high turnover rate of CA. It is easy to be limited by transport of reactant and/or product within the immobilization matrix, if the immobilization technique retards transport.…”

Biomimetic Catalysis of CO2 Hydration: A Materials Perspective

“…Therefore, the epoxy functionalized SBA-15 had higher activity than the amino functionalized SBA-15. 160 CA has also been immobilized on other supports such as chitosan, 65,68,69,71 mesoporous aluminosilicates, 67 polyurethane foam, 161,162 CaCO 3 crystalline composite, 163 chitosan-SiO 2 -γ Fe 2 O 3 particles, 164 chitosan−alginite polyelectrolyte complex, 82 nylon tubes, 92 porous glass, 165 activated carbon, 165 enzyme biomimetic silicification, 90,166 granular silica (Sipernat 22), 167 cross-linked enzyme aggregates, 168 polyester polymer 80, 169 iron manganese nanoparticle, 84 carboxylated polyaniline nanofibers, 170 ferroferric oxide microspheres, 171 nonporous silica nanoparticles, 172 algenite polymers, 173 titania nanoparticles, 174,175 polypyrrole films, 176 Amberlite, 177 self-assembled enzyme nanoparticle, 178 polyacrylamide beads, 179 agarose gels, 180 epoxy-functionalized magnetic polymer microspheres 181 and Nafion. 182 All the immobilized enzymes showed lower activities than the free enzyme.…”

Development of Small-Scale Experiments for the Education of Chemical Engineering and Its Practice for Undergraduates

“…In chemical syntheses, harmful or unwanted gases are sometimes generated and therefore must be removed (Zidar et al, 1997;Li et al, 2017). In chemical plants, an absorption tower is utilized, where various types of sorbents are typically packed and water or other solvents (absorption liquid) is flown down from the top, while the gases are flown in the direction opposite from the bottom (Liu et al, 2013).…”