The half-life time can be obtained from the deactivation constant, kd, using the relation:
(63)
Continuous operation sometimes lessens the stability when compared with a batch reactor
(Mukesh et al., 1993). Nevertheless, in enzyme membrane reactors a deactivation of
about 3% per day or less has been described (Kragl et al., 1996). The enzyme
stabilisation achieved may be a consequence of substrates presence. Supporting this
hypothesis the
Figure 7.7 Representation of relative
cutinase activity against time during
continuous operation using a flow rate
of 0.1 ml/min. The correlation of the
results was made using an exponential
deactivation model (––). (From
Carvalho et al., 2001a)
reaction mechanism involves an acyl-enzyme complex in the first step, and this complex
formation during reaction may account for cutinase stabilisation (Carvalho et al., 2001a).
Leakage of enzyme through the membrane associated with the continuous start-up can
be considered a common phenomenon in membrane reactors (Deeslie and Cheryan, 1981;
Bressollier et al., 1988). The consequence is an initial decrease in conversion.
Linear velocity and flux regimen in the membrane moduleThe linear recirculation velocity through the tubular membrane module is given by:
(64)
Reversed micellar bioreaction systems 223