Abstract
Here, the immobilization of the urease enzyme within polyethyleneimine (PEI) cryogels (Urease@PEI cryogel) is reported during the synthesis via the entrapment method. The immobilization yield of the enzymes within PEI cryogels was determined as >85%, and the activity% of the prepared Urease@PEI cryogel systems was calculated as >90% with respect to equal amounts of native urease enzyme. The working stability of Urease@PEI cryogel systems was observed to be better than native urease enzymes in the pH range of 5.0–9.0 and the temperature range of 15–45 °C. Furthermore, the immobilization of urease enzyme within PEI cryogels afforded great performance for use in continuous systems with more than 70% activity. Moreover, Urease@PEI cryogel systems preserved more than 50% activity even after 20 consecutive uses and showed superior storage stability, e.g., storage at 25 °C for 10 days resulted in >50% activity. Most importantly, the possible utilization of Urease@PEI cryogel systems for CO2 adsorption, which is the byproduct of the enzymatic reaction of urea, from the reaction media was investigated. The CO2 capture capability was calculated as 0.42, 0.27, and 0.11 cm3/g at 1 bar and 25 °C for Urease@PEI-1, Urease@PEI-2, and Urease@PEI-3 cryogels, respectively.
