Use of metal chlorides during waste wheat straw autohydrolysis to overcome the self-buffering effect.

High ash content of waste wheat straw (WWS) is resistant to biorefinery autohydrolysis pretreatment due to its self-buffering effects. In this work, minor addition FeCl ₃ and AlCl ₃ were applied to overcome the self-buffering effects of WWS by cationic occupation of the negatively charged sites present on particulate ash's surface. The results showed that with the increasing concentrations (0-20 mM) of AlCl ₃ and FeCl ₃ , the enzymatic efficiencies of autohydrolyzed WWS were enhanced from 49.7% to 62.1% and 66.6%, respectively. Acid buffer and cation exchange capacity of pretreated WWS were decreased by adding metal chlorides and the reducing results were mainly attributed to cation exchange. Meanwhile, a maximum monosaccharide production (185.3 mg/g-WWS) was achieved with 62.0 mg/g-WWS xylooligosaccharide by using 20 mM FeCl ₃ during WWS autohydrolysis. The results demonstrated that the implications of FeCl ₃ and AlCl ₃ in WWS autohydrolysis were an effective strategy to enhance autohydrolysis efficiency by overcoming self-buffering effects.
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