N. Diano et al., The process of thermodialysis and the efficiency increase of bioreactors operating under non-isothermal conditions, J MOL CAT B, 11(2-3), 2000, pp. 97-112
When a catalytic membrane is employed in a non-isothermal bioreactor its ac
tivity increases as a direct function of the applied temperature gradient a
nd decreases when both average temperature or substrate concentration incre
ase. To know the physical cause responsible for this behaviour substrate fl
uxes have been studied under isothermal conditions (diffusion) and non-isot
hermal conditions (thermodialysis). Strong analogies between the behaviour
of the catalytic membrane and the substrate fluxes produced by the process
of thermodialysis have been observed. By introducing diffusive and thermodi
ffusive substrate fluxes in appropriate mass balance equations the substrat
e concentration profiles into the catalytic membrane have been deduced by c
omputer simulation. In absence of catalysis and under non-isothermal condit
ions the profiles are higher than the ones corresponding under comparable i
sothermal conditions, while the contrary occurs in the presence of catalysi
s. The percentage increases of enzyme activity, calculated by the curves of
the substrate concentration profiles, show the same temperature and concen
tration dependence than those actually observed with the catalytic membrane
. The role of thermodialysis in affecting the enzyme activity in non-isothe
rmal bioreactor has been discussed and demonstrated. (C) 2000 Elsevier Scie
nce B.V. All rights reserved.