Abstract
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•Basic ethanolamine-based DESs are cost-effective and easily prepared solvents.•ChCl: MEA is found highly effective in wheat straw pretreatment.•Strong basicity of DESs results in more lignin removal.•Polysaccharide loss is inhibited by basic ethanolamine-based DESs.•Enhancement of hydrolysis by lignin removal is verified by XRD, SEM and FT-IR.
A series of ethanolamine based deep eutectic solvents (DESs), which have strong basicity, were firstly applied in wheat straw pretreatment. Typically, choline chloride: monoethanolamine (C:M) as the best solvent among these DESs can remove 71.4% lignin and reserve 93.7% cellulose (70 °C, L/S mass ratio of 20:1, 9 h), and improve the enzymatic hydrolysis of residue, i.e., 89.8% cellulose and 62.0% xylan conversion. The pretreatment capacity of C:M is comparable to other solvents while C:M has several advantages, e.g., lower cost with cheap materials and simpler preparation process, mild conditions and lower polysaccharide loss. The XRD, SEM and FT-IR results verified that the polysaccharide conversion and sugars yield were enhanced by the removal of lignin in the pretreatment process. The basic ethanolamine based DESs are promising solvents for industrial application of wheat straw pretreatment.