Effect of Initial pH on H2 Production by Clostridium butyricum T4 from the Mixture of Xylose and Glucose

We conducted batch experiments to investigate the effect of an initial pH ranging from 4.5 to 9.5 on fermentative H-2 production by Clostridium butyricum T4 from the mixture of glucose and xylose (3:1, mol/mol). At pH 4.5 and pH 9.6, sugar was consumed, but hydrogen was not produced. At pH 5.2-8.4, hydrogen was constantly released, and the cumulative H-2 production and specific H-2 production rates first increased and then decreased with increasing pH. The cumulative H-2 production and specific H-2 production rates peaked at an initial pH of 7.6 and subsequently decreased as the pH increased. The highest volume and rate were 4.26 L/L and 18.86 mmol/h . g-cdw, respectively. The results show that an initial fermentation system with neutral or alkaline pH can reduce the "glucose effect" and is more conducive to the absorption of different substrates in a mixed substrate system for fermentative H-2 production by Clostridium butyricum T4.