NOVELTY - Treatment of lignocellulosic biomass (100) includes incubating a lignocellulosic biomass comprising lignin, cellulose, and hemicellulose in an ionic liquid (IL) (200) for a time and temperature to swell the cellulose and hemicellulose without dissolution of the biomass in the IL; washing the IL-incubated biomass (400) with a liquid non-solvent for cellulose that is miscible with water and IL; contacting the swelled washed biomass with an aqueous buffer comprising enzymes capable of hydrolyzing (500) both cellulose and hemicellulose to produce polysaccharides; and recovering lignin.    USE - The method is for treatment of lignocellulosic biomass i.e. agricultural residue, wood and forest residue, kudzu, red algae, herbaceous energy crop and/or plant biomass. It is useful for extraction of monomeric compound i.e. one or more of 81 compounds e.g. toluene, phenol, 2-methylphenol, 3-methylphenol, 1-methylindane, 2-methoxyphenol, 4-methoxy-3-methylphenol, naphthalene, 2-methoxy-5-methylphenol, 2-methoxy-4-methylphenol, 3,4-dimethoxytoluene, 3,4-dimethoxyphenol, 3-methoxyphenol-1,2-benzenediol, 4-ethyl-2-methoxyphenol, 2-methylnaphthalene, 1-methylnaphthalene, 2-methoxy-4-vinylphenol, 4-ethyl-1,2-dimethoxybenzene, 1,2,4-trimethoxybenzene, 2,6-dimethoxyphenol, 3-allyl-6-methoxyphenol, and 2-methoxy-4-propylphenol from lignin; and conversion of lignin of lignocellulosic biomass to chemicals i.e. phenol, guaiacol, syringol, eugenol, catechol, vanillin, vanillic acid, syringaldehyde, benzene, toluene, xylene, styrene, biphenyl and/or cyclohexane. The agricultural residue is corn stover, wheat straw, bagasse, rice hulls, or rice straw. The wood and forest residue is pine, poplar, Douglas fir, oak, saw dust, paper/pulp waste, or wood fiber. The herbaceous energy crop is switch grass, reed canary grass, or Miscanthus (all claimed). The method is useful in production of renewable fuels, chemicals and materials such as ethanol, butanol, lactic acid, gasoline, biodiesel, methane, hydrogen, plastics, composites, protein, drugs, or fertilizers. The lignin extracted by the method is used in cement and concrete, antioxidant, asphalt, animal feed pellets, animal feed molasses additives, road binder/dust control, pesticides, oil well drilling muds, adhesives, resins and binders, wallboard, dispersants, emulsifiers and wetting agents, agglomerants, chelants, leather treatment, antibacterial activity, lead acid batteries, oil recovery, water treatment, industrial cleaners, emulsion stabilizers, carbon black, inks and azo pigments, dyestuffs, micronutrients, fertilizers bricks, refractories and ceramic additives, ore processing, or kitty litter.    ADVANTAGE - The method results in efficient lignin fraction generation and high yield of chemicals from lignin and enables economic recovery of catalyst and chemicals. The organic compounds fractionated are surprisingly pure. Thus, they are valuable by-products of lignin purification and can be commercially utilized to decrease the cost of the overall process and constitute use for the lignin fraction.    DETAILED DESCRIPTION - Treatment of lignocellulosic biomass (100) comprises incubating a lignocellulosic biomass comprising lignin, cellulose, and hemicellulose in IL (200) for a time and temperature to swell the cellulose and hemicellulose without dissolution of the biomass in the IL; washing the IL-incubated biomass (400) comprising lignin, cellulose and hemicellulose with a liquid non-solvent for cellulose that is miscible with water and IL; contacting the swelled washed biomass comprising lignin, cellulose and hemicellulose with an aqueous buffer comprising enzymes capable of hydrolyzing (500) both cellulose and hemicellulose to produce polysaccharides; recovering the lignin; and converting lignin to chemicals. INDEPENDENT CLAIMS are included for:    (1) extraction of monomeric compound from lignin comprising mixing biomass with IL to swell the biomass and not dissolve the biomass in IL; washing the treated biomass; hydrolyzing the treated biomass; separating the cellulosic and lignin fractions; and subjecting the lignin fraction to hydrothermal processing (700);    (2) conversion of lignin of lignocellulosic biomass to chemicals comprising mixing biomass in IL to swell the biomass and not dissolve the biomass in IL; applying radio frequency (RF) heating to the swelled biomass to heat to a target temperature range; applying ultrasonic, electromagnetic (EM) (300), convective and/or conductive heating to the swelled biomass to maintain the biomass at the target temperature range; washing the treated biomass; separating the cellulosic and lignin fractions; and subjecting the lignin fraction to hydrothermal processing; and    (3) disruption of the structure of lignocellulosic biomass comprising incubating a biomass in IL and applying RF heating and ultrasonic, EM, convective and/or conductive heating; washing the treated biomass; recovering the lignin; and subjecting the lignin fraction to hydrothermal processing.    DESCRIPTION OF DRAWING(S) - The drawing is a flowchart illustrating a method for treating lignocellulosic biomass.    Lignocellulosic biomass (100)    Incubating lignocellulosic biomass in IL (200)    EM heating (300)    Washing IL-incubated biomass (400)    Hydrolyzing (500)    Hydrothermal processing (700)