Thermodynamic study and optimization of hydrogen production by Enterobacter aerogenes

10102) utilizing starch hydrolysate as substrate. An optimum pH range corresponding to 6.1– 6.6 is the main evidence of batch runs carried out at di3erent pHs. An optimum value of temperature corresponding to 40◦C is experimentally determined by means of batch fermentation runs carried out at di3erent operative temperatures. A thermodynamic study, which was performed developing the Arrhenius approach, allows the estimation, for both fermentation and thermal inactivation, of the activation enthalpies (67.3 and 118:1 kJ mol−1) and of the correlated entropies (−0:087 and −0:46 kJ mol−1 K−1). ? 2001 International Association for Hydrogen Energy.