Due to a significant increase in biomass, Populus wood is a very promising material as a biogas source. However because of the high lignin content and its complex structure, it undergoes the biodegradation process under anaerobic conditions more slowly and in a more difficult manner than other lignocellulose materials applied to fermentation processes. The mutual approach for biogas production is pretreatment application which aims at loosening the cellulose structure and reducing the amount of lignin. One of pretreatment methods is acid hydrolysis which leads to a break of chemical bonds between carbohydrates and lignin and it makes lignocellulose material swell. Such a preparation of a feedstock leads to its better availability for microorganisms but it may create inhibitors. The knowledge of chemical changes occurring during pretreatment can be useful in predicting the efficiency of the fermentation processes.
In the investigations two species of Populus gained from different short rotation copies plantations were tested. The pretreatment was carried out with 3 and 7%w/w H2SO4 solutions at 100°C for 2h. The chemical changes of Populus after pretreatment were analysed by the gravimetric method and included determination of carbohydrates and a lignin content. Fourier transform infrared (FTIR) was used to analyse the changes in a chemical structure of lignin, hemicelluloses and cellulose after acid pretreatment. On the basis of the results, the effect of acid pretreatment on the content of chemical components was observed. The changes in chemical composition after acid pretreatment were observed in minor substances dissolved in organic solvents and water. It was also observed that a content of lignin is higher after acid pretreatment. Applying two solutions of H2SO4 showed that its concentration influences a content of main components which are important during biogas production. Infrared spectroscopy indicated reduction of cellulose crystallinity due to acid treatment.
Keywords: biogas production, acid pretreatment, lignocellulose material
Authors
Zborowska M.
Institute of Chemical Wood Technology, Poznan University of Life Sciences, Poznan, Poland
Waliszewska H.
Institute of Chemical Wood Technology, Poznan University of Life Sciences, Poznan, Poland
Waliszewska B.
Institute of Chemical Wood Technology, Poznan University of Life Sciences, Poznan, Poland
Stachowiak- Wencek A.
Institute of Chemical Wood Technology, Poznan University of Life Sciences, Poznan, Poland
Boruszewski P.
Department of Technology and Entrepreneurship in Wood Industry, Warsaw University of Life Sciences, Warsaw, Poland
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