Effect of ionic liquid/inorganic salt/water pretreatment on the composition, structure and enzymatic hydrolysis of rice straw

Albeit ionic liquid (IL) pretreatment has been demonstrated to effectively enhance the saccharification of lignocellulosic biomass , extremely high costs of ILs still restrict its scale-up. If the ILs at high water content can be used as pretreatment solvents for lignocellulosic biomass, the chemical costs will be significantly reduced. However, the dissolving capacity of the ILs was notably decreased when water contents exceeded within limits. In this work, inorganic salts (K 3 PO 4 and K 2 CO 3 ) were added as additives of imidazolium-based IL/water systems to improve tolerance of ILs in the presence of water. The pretreatment with 50% 1-ethyl-3-methylimidazolium chloride ([C 2 mim]Cl) + 49.5% water + 0.5% K 2 CO 3 at 95 °C for 3 h improved lignin removal to 69.32%, and also increased the surface areas as compared to untreated rice straw. The reducing sugar yield of the regenerated materials was increased to 82.45% after 72 h enzymatic hydrolysis .