Preparation of enzymatic microchannel reactor with immobilized urease-crosslinked enzyme aggregates and its performance

Abstract

Urine recovery has been achieved through physical-chemical technologies on space station presently, but it requires harsh operation conditions and careful equipment maintenance. Here, a novel microreactor that combined microchannel and urease-crosslinked enzyme aggregates (urease-CLEAs) was prepared to mildly reclaim water and nitrogen nutrient from urine. First, the material that was suitable to make microchannel reactor and immobilize urease-CLEAs was selected from five organic materials, and poly(methyl methacrylate) was the best one. Second, the immobilization conditions for urease-CLEAs were optimized. Microchannel reactor with immobilized urease-CLEAs (CLEAs-microreactor) showed the highest activity of 0.54 U/cm² under the optimal conditions of precipitant 20 % acetone, crosslinker 2.0 % glutaraldehyde, and 2.0-hour precipitation/crosslinking. CLEAs-microreactor showed good stability of pH, thermal, and storage compared with the microchannel reactor with immobilized free-urease (Free-microreactor). The efficiency of CLEAs-microreactor reached the highest of 101.8 μmol/h, which was 2.24-fold of Free-microreactor. This study provides an alternative technology for the recovery of water and nitrogen nutrient from urine on space station.