Co-production of bioethanol and furfural from poplar wood via low temperature (≤90 °C) acid hydrotropic fractionation (AHF)

[Display omitted] •Optimizing pretreatment of poplar using a recyclable acid hydrotrope ≤90 °C.•Bioethanol production from acid hydrotrope fractionated water insoluble solids.•Furfural production from the acid hydrotrope spent liquor. Poplar wood was fractionated into a water-insoluble cellulosic solid (WIS) fraction and a spent liquor that contained mainly dissolved lignin and xylan using an acid hydrotrope, p-Toluenesulfonic acid (p-TsOH), at low temperatures (≤90 °C). Reaction-kinetics-based severities were used to scale-up fractionation using 100 g wood at p-TsOH concentration 50 wt% and 90 °C for 112 min. The WIS and spent liquor from a scale-up run were used to produce bioethanol and furfural, respectively. At 15% WIS loading (w/v), maximal ethanol concentration was 52.47 g/L with a fermentation efficiency of 68.3%. Direct dehydration of the virgin spent liquor resulted in a maximum furfural concentration of 5.44 g/L at 68.4% yield. Precipitating lignin in the spent liquor increased furfural concentration to 6.18 g/L and yield to 77.7%. These results demonstrate the potential of acid hydrotrope fractionation for forest biorefinery.