Abstract

Reactions catalyzed with immobilized enzymes are widely used in biotechnology. Such reactions occur in a heterogeneous system because the reaction takes place in the solid phase represented by the biocatalyst, while substrates and products are generally soluble in the liquid medium where the course of reaction is being monitored. This reaction system confronts heat and mass transfer problems, which consequently affect the observed rate of reaction. If the enzyme is immobilized on the surface of a non-porous support, external diffusional restrictions are likely to occur, due to the formation of a stagnant layer in the proximity of the biocatalyst solid surface. This review analyzes the influence of external mass and heat transfer rates on the reaction kinetics of immobilized enzymes under agitation, presenting and discussing the different mathematical models that have been proposed and their underlying assumptions.