Effects of hydrochloric acid washing on the microstructure and pyrolysis bio-oil components of sweet sorghum bagasse.

•Hydrochloric acid washing removed 94.25% of the metal content.•Pretreated sweet sorghum bagasse had an obviously loose porous structure.•Hydrochloric acid washing reduced the varieties of bio-oil compounds.•Pretreatment significantly enhanced the d-allose and ketones contents in bio-oil.