Mechanistic insights into morphological and chemical changes during benzenesulfonic acid pretreatment and simultaneous saccharification and fermentation process for ethanol production

[Display omitted] •SSF process of BA-treated MS was conducted with 47.45 g/L production of ethanol.•Massive removal of hemicellulose and lignin were visualized in situ by FM and CRM.•G units depolymerized more easily than S units during BA pretreatment.•The relative content of H units increased due to the demethoxylation of G/S units. The anatomical and histochemical characterization of pretreated substrates is essential for the further valorization of biomass during the biorefinery process. In this work, the benzenesulfonic acid (BA)-treated substrates were employed for simultaneous saccharification and fermentation (SSF) of ethanol for the first time. An ethanol yield of 50.36% was attained at 10% solids loading and 47.45 g/L of ethanol accumulated at 30 % solids loading. The dramatic improvements could result from the deconstruction of cell walls, which were evidenced by fluorescence microscope and confocal Raman microscopy spectra. Additionally, for a thorough comprehension of the inherent chemistry of lignin during the BA pretreatment, the changes in lignin structure features were identified for the first time by gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR). In summary, this study tried to probe the possibility of BA-treated Miscanthus for the SSF process and unveiled the mechanism of the efficient BA pretreatment.