The objective of this research was to study the influence of delignification, caused by NaOH, on lignin chemistry. Miscanthus × giganteus samples were pretreated with various concentrations of sodium hydroxide (0.5, 1.0,… Click to show full abstract
The objective of this research was to study the influence of delignification, caused by NaOH, on lignin chemistry. Miscanthus × giganteus samples were pretreated with various concentrations of sodium hydroxide (0.5, 1.0, and 2.0%, w/v) at different pretreatment times (15, 30, and 60 min) in batch systems. Results indicated that NaOH had a significant effect on lignin removal with delignification ranging from 42.3 to 84.6% depending on the severity of pretreatment. Nitrobenzene oxidation was used to investigate changes in lignin chemistry of pretreated M. giganteus by analyzing syringyl to guaiacyl ratio (S/G ratio) and p-hydroxyphenyl to guaiacyl ratio (H/G ratio). The S/G ratio of pretreated Miscanthus increased from 0.64unpretreated sample to 0.77 while the H/G ratio decreased from 0.48unpretreated sample to 0.28 at 0.5% NaOH pretreatment suggesting that H unit of lignin was most susceptible to NaOH pretreatment. The data also suggested that NaOH concentration was a critical factor in changing lignin chemistry of pretreated Miscanthus. A better understanding of the correlation between pretreatment severities, changes in lignin chemistry, and enzymatic hydrolysis efficiency subsequent to pretreatment of herbaceous grasses warrant further investigations.
               
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