Biomimetic carbon dioxide sequestration using immobilized bio-composite materials

• ESMAl with high surface area appears promising for the CA immobilization.
• The Km and Vmax of CAImESMAl was found to be 5.3 mM and 1.753 μmoles/ml/min, respectively.
• The HLP at 25 °C improved by a factor of 1.2 for CAImESMAl.
• Proof of concept has been established for carbonation reaction.
• The CaCO3 was characterized by XRD and SEM analysis confirms calcite nature of CaCO3.

Mesoporous alumina has been synthesized using egg shell membrane (ESM) as template. Aluminum ion has been loaded on ESM by simple adsorption technique and then calcined to obtain the mesoporous alumina. The characterizations of alumina loaded ESM (ESMAl) have been done by various techniques like XRD, TEM, EDX and surface area. From immobilization studies the optimum pH and temperature for free and immobilized CA were determined to be 7.5 and 25 °C, respectively. The Km and Vmax of immobilized CA was found to be 5.3 mM and 1.753 μmoles/ml/min by p-NPA assay. The storage stabilities for free and immobilized CA were performed at 25 °C and it was found that the half life period for immobilized CA has been improved by a factor 1.25 as compared to free CA. From leaching study the immobilized CA could be reused up to 7th cycles. The carbonation capacity of immobilized CA was found to be 24.84 mg of CaCO3/mg of enzyme as compared to 33.05 mg of CaCO3/mg of enzyme for free CA.

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