Effects of soaking aqueous ammonia pretreatment on chemical composition and enzymatic hydrolysis of corn stover. The aim of this research was to investigate the effect of applying two different temperatures of the soaking aqueous ammonia treatment on the chemical composition and enzymatic hydrolysis yield of the corn stover. Native corn stover as well as solid fractions after 20 h of alkali pretreatment performed at 15% ammonia solution and at 50 °C or 90 °C were analysed in terms of cellulose, holocellulose, lignin and extractives content. Both untreated and treated samples were subjected to the enzymatic hydrolysis and hydrolysates were examined with a high performance liquid chromatography (HPLC). Results indicated a significant development of enzymatic digestibility of the SAA treated biomass. Furthermore, a 38.7% and a 68.9% delignification levels in the biomass treated with ammonia at respectively 50 °C and 90 °C process comparing to the raw material were achieved.

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Effects of soaking aqueous ammonia pretreatment were considered for fast-growing poplar wood in the context of bioethanol production. The milled Populus trichocarpa wood with a particle size of 0.43 to 1.02 mm was pretreated at two temperatures (50 °C and 90 °C) and two concentrations of ammonia solution (15% and 20% w/w) for 20 h. The lignin content decreased by 46% in the biomass treated with the most severe conditions. After enzymatic hydrolysis, the sugar yield was analysed, and the results indicated that increased temperature and ammonia concentration during pretreatment resulted in higher glucose content. Additionally, changes in the degree of polymerization and available pore volume were investigated.

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Inhibitory compounds formation after liquid hot water (LHW) pretreatment of corn stover as an alternative to wood lignocellulosic feedstock for bioethanol production. Thus far, corn stover has been perceived as a promising lignocellulosic alternative to wood intended for bioethanol procurement, however it should be recognised also as a potential future component in a mixed biomass system. The aim of this research was to investigate the effect of applying different hydrothermal treatment conditions on the potential inhibitory compounds formation from corn stover. An analysis of selected inhibitory compounds formed after pretreatment performed at different temperatures (160°C, 175°C, 190°C and 205°C) was carried out. Furfural, simple sugars and lignin were some of the inhibitors examined with HPLC and UV-VIS spectrophotometric methods. Furthermore, the chemical composition of organic extracts obtained from native and LHW pretreated biomass was analyzed qualitatively with GC-MS method and inhibitory compounds like vanillin, sitosterol or syringol were detected. As a result of those investigations compared to enzymatic hydrolysis yield the temperature of 175°C was chosen as the most promising condition of corn stover LHW pretreatment in terms of the efficiency of the subsequent phases of bioethanol production.