Biological hydrogen gas production from lignocellulosic materials

The energy limitation in the world diverted the attentions to clean and renewable energy sources. Hydrogen is one of the clean and renewable energy sources with high energy value. Therefore, it is considered as source of energy in the future. Second generation cellulosic wastes as lignocellulosic biomasses from such as agricultural activities can be used as carbon source in order to achieve clean, carbon-neutral and efficient biohydrogen production. In this study, hydrogen production from one of the lignocellulosic wastes, Pinus brutia (pinewood) chips by dark fermentation was investigated. Wood chip was subjected to acid and alkaline hydrolysis to obtain sugar solution to be used in hydrogen production by dark fermentation. Box-Behnken statistical experimental design method was used to determine the significant factors that affect total sugar formation after hydrolysis. The independent variables were acid or alkaline concentration, wood chip concentration, hydrolysis temperature and period. Stat-Ease Design Expert software was used to develop quadratic responses equation and to determine optimum hydrolysis conditions for the maximization of total sugar concentration. Acid hydrolysis resulted in higher sugar formation compared to alkaline hydrolysis. The optimal conditions for acid hydrolysis were determined as 8 percent substrate concentration, 8 percent acid concentration, 121 degrees Celsius and 15 minutes hydrolysis period with maximum sugar concentration of 40 g/L by using Stat – Ease Design expert software. The hydrolyzed wood chip was subjected to the dark fermentation for biohydrogen production. The effect of initial total sugar concentration on the yield of production was investigated. The maximum yield was obtained as 0,6 mol/mol at initial total sugar concentration of 1 g/L. Keywords: Biohydrogen, dark fermentation, hydrolysis, lignocellulosic materials, wood chips.