Chemical Engineering Journal, Vol.278, 122-128, 2015
Flexible film-type catalysts encapsulating urease within kappa-carrageenan hydrogel network
Flexible film-type catalysts were synthesized by encapsulating urease within a kappa-carrageenan gel network supported on a cellulose-acetate membrane filter. Synthesized film-type catalysts are flexible and can be easily formed into a shape that is suitable for a specific process configuration. The filter membrane has macropores about 200 nm, which are formed by interconnected bead-shaped membrane material. Scanning electron microscopy shows that the surface of the membrane material is coated homogeneously with the kappa-carrageenan hydrogel. Urease entrapped within the gel network hardly leaches out during urea hydrolysis catalysis conducted at 310 K in a batch reactor and exhibits high catalytic performance. Analysis of the reaction data by the Michaelis-Menten equation shows that the film-type catalyst shows kinetic parameters (K-M and V-max) and apparent activation energy (24 kJ mol(-1)), which are all similar to those found for free urease. Estimation of the mass transfer rate of urea within the kappa-carrageenan network and the urea hydrolysis rate show that the diffusion rate of urea within the thin film is five orders of magnitude higher than the reaction rate. The film catalyst can be recycled at least 7 times with <20% decrease in activity. High flexibility as well as high catalytic performance of the film catalyst shows prospective features of this catalyst for future applications. (C) 2014 Elsevier B.V. All rights reserved.