Immobilized enzymes bioreactors utilizing a magnetic field: A review

The main objective of this article is devoted to reviewing all previous contributions concerning immobilized enzyme bioreactors utilizing a magnetic field. These reactors used magnetic supports or beads with immobilized enzymes as the solid phase. All published researches from the early beginning after the middle of the last century to the present time are discussed and analyzed. These papers used the magnetic field for several purposes including mixing, attracting the particles to prevent their washout from the column and to operate with higher substrate velocities to enhance mass transfer processes. It was found that axial magnetic field is the most preferable for most researchers. In addition, most of the magnetic particles were prepared by entrapment. Many enzymes such as Glucose oxidase, Urase and Hydrdlase were immobilized on different supports in these reactors. In most applications, the magnetic field indirectly enhances the immobilized enzymatic activity and the conversion rate. This enhancement is attributed to the improved mass transfer process between the liquid medium and the immobilized enzyme since the applied magnetic field enables an intensive mixing or the operation with higher medium flow rates. Some comments were presented at the end of the review which shows the gaps in this promising application. (C) 2017 Elsevier B.V. All rights reserved.