NOVELTY - A composition comprises first liquid phase and a solid or second liquid phase which is obtained by contacting (a) a first solution comprising a water-miscible ionic liquid (IL), a polar-aprotic solvent, optionally a weak hydrogen bonding solvent, and optionally a biomass, lignin, or cellulose; and (b) a polar-protic solvent.    USE - In chemical, pharmaceutical, biofuel, or other industrial application using ionic liquids (ILs) as part of their process, such as research, commercial manufacturing, and perhaps even large scale processing of commodity materials and fuel; in biomass processing or biofuels and other biomaterials, paper recycling and pulp processing for paper manufacturing; for the fractionation and purification of ILs and solutes dissolved in ILs; and in the separation and recovery of IL, lignin, and sugars dissolved in ILs as part of an IL biomass pretreatment process.    ADVANTAGE - The solvent composition with an optimum molar ratio of acetone:alcohol:ionic liquid is 4-6:1:1 does not result in the formation of gel phases during precipitation of biomass from ionic liquid solutions. The alcohols are more effective at reducing the ionic liquid content of precipitated LBM by washing than the acetone containing precipitation solvent, and that a combination of ethanol and water wash regimens is capable of reducing residual ionic liquid content in pretreated corn stover to less than 0.2 wt./wt.%. The large number of adjustable parameter in the ionic liquid recycling process suggests that higher recycling efficiencies and yields are possible through process optimization.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a method (M1) involving: contacting or mixing (i) a first solution comprising a ionic liquid and a biomass or a cellulose, and (ii) a second solution comprising a ketone and an alcohol solution to form a third solution, where the biomass or cellulose precipitates or becomes solid and the third solution does not form a gel or have a viscous intermediate phase, the second solution is a precipitating solution, and the third solution is a precipitating mixture; and    (2) recycling (M2) ionic liquid in a pretreatment process, involving: (a) providing a first solution comprising cellulose and/or lignocellulosic biomass (LBM), an IL, a ketone and an alcohol in a molar ratio of X:Y':Z', such that the cellulose and/or LBM are solid or precipitated, (b) washing the second solution with an alcohol wash to produce a solid portion and a liquid portion, where the solid portion comprises the precipitated cellulose and/or LBM, (c) separating the solid portion and the liquid portion, (d) adding a Cascade Wash B, comprising 2-propanol, to the liquid portion, (e) distilling the liquid portion to remove at least a portion of the ketone and the 2-propanol, (f) adding acetone to the remaining liquid from step (e) to form a first extract, (g) adding a mixture of a ketone and 2-propanol to form a second extract, (h) extracting the IL in the first and second extracts, and (i) extracting lignin from the remainder of the remaining after the removal of the first and second extracts.    X=greater than 3;    Y'=0.8-1.2;    Z'=1.