Hydrolysis characteristics and kinetics of waste hay biomass as a potential energy crop for fermentable sugars production using autoclave parr reactor system

The use of the organic fraction of municipal solid waste crops has received considerable attention as a sustainable feedstock that can replace fossil fuels for the production of renewable energy. Therefore, municipal bio-waste in the form of hay was investigated as a potential energy crop for fermentable sugars production. Hydrolysis of hay by dilute phosphoric acid was carried out in autoclave parr reactor, where reactor temperature (135–200 °C) and acid concentration (2.5–10% (w/w)) were examined. Analysis of the decomposition rate of hemicellulosic biomass was undertaken using HPLC of the reaction products. Xylose production reached a maximum value of 13.5 g/100 g dry mass corresponding to a yield of 67% at the best identified conditions of 2.5 wt% H3PO4, 175 °C, 10 min reaction time, and at 5 wt% H3PO4, 150 °C, and 5 min reaction time. For glucose, an average yield of 25% was obtained at 5 wt% H3PO4, 175 °C and 30 min. Glucose degradation to HMF was achieved at 10 wt% H3PO4 and 200 °C. The maximum yield for produced arabinose was an average of 3 g/100 g dry mass corresponding to 100% of the total possible arabinose. The kinetic study of the acid hydrolysis was also carried out using the Saeman and the Two-fraction models. It was found for both models that the kinetic constants (k) depend on the acid concentration and temperature. For xylose and arabinose it was found that the rate of formation was more favoured than the rate of degradation. By contrast, for glucose it was found that glucose degradation was occurring faster than glucose formation. It can be concluded that dilute phosphoric acid hydrolysis of hay crop is feasible for the production of fermentable sugars which are essential for bioethanol synthesis.

► Hay was investigated as a potential energy crop for fermentable sugars production.
► Hydrolysis of hay by dilute H3PO4 acid was carried out in autoclave parr reactor.
► Xylose yield reached a maximum value of 67%.
► An average yield of 25% was obtained for glucose.
► The rate of formation of xylose and arabinose was more favoured than the rate of degradation.