Kinetic and thermodynamic analysis (with statistical optimization) of hydrogen production from crude glycerol using Clostridium pasteurianum

Abstract

This study presents kinetic and thermodynamic analysis of crude glycerol fermentation for hydrogen production. Fermentation parameters have been optimized using central composite design (CCD) of experiments as: pH = 6.7, temperature = 36 °C, crude glycerol concentration = 7.4 g/L. Kinetic and thermodynamic analysis has been done using Haldane substrate inhibition model, Arrhenius plots and Eyring equation. Kinetic parameters Vmax and Km increase, while KI reduces for crude glycerol, as compared to pure glycerol. Moreover, activation energy (217 kJ/mol) and ΔG (103 kJ/mol) for crude glycerol are lesser than pure glycerol. Consequently, hydrogen yield in crude glycerol fermentation (0.627 mol H2/mol glycerol with 44% v/v H2 in product gas) is significantly higher than pure glycerol. Role of Na+ ions in improving crude glycerol fermentation has been experimentally confirmed. Kinetic and thermodynamic parameters for crude glycerol fermentation determined in this study have quantitatively substantiated its potential for biohydrogen production.