Thermochemical pretreatment with ionic liquids for enhancing fermentative hydrogen production from rice husk

초록

This study presents the efficacy of thermochemical pretreatment for extracting lignin and enhancing fermentative hydrogen production from a refractory biomass feedstock, rice husk (RH), using three different chemical agents: two ionic liquids ([EMIM][Ac] and [EMIM][Cl]) and the alkali (NaOH). [EMIM][Ac] and NaOH exhibited similarly high lignin extraction efficiencies, both noticeably higher than that of [EMIM][Cl]. Pretreatment with both chemical agents also altered the physical structure of RH, observed through scanning electron microscopy (SEM) images, and affected the hydrolysable sugar composition. Given the improved pretreatment performance, RHs pretreated with [EMIM][Ac] and NaOH showed approximately 11-fold and 9.5-fold higher hydrogen production potential, respectively, compared with untreated RH during anaerobic batch fermentation. Furthermore, microbial community analysis revealed a significant shift in population structure during hydrogen fermentation, particularly when RHs pretreated with [EMIM][Ac] and NaOH were used as feedstock. Principal component analysis demonstrated that the microbial communities associated with both pretreated RHs were highly identical to each other but markedly different from that of untreated RH. The genera Clostridium and Caproiciproducens played key roles in enhancing hydrogen production from RHs.

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