Patent ID: 8053566

Claim:
A method for isolating a lignin preparation from a plant material comprising: (a) contacting the plant material with an aqueous ethanol solution at an elevated temperature and an elevated pressure for a retention time sufficient to produce a liquid solvent mixture comprising ethanol, ethanol-soluble lignin and water, and a plant pulp material; (b) separating the plant pulp material from the liquid solvent mixture; (c) precipitating the ethanol-soluble lignin and forming lignin particulates by diluting the liquid solvent mixture with an aqueous gasified solution containing dissolved gas under conditions that promote the formation of gas bubbles, whereby the gas bubbles attach to precipitated lignin particulates as they form, and the precipitated lignin particulates are transported to the liquid surface by attachment to the gas bubbles; (d) harvesting the precipitated lignin from the liquid surface; and (e) recovering an isolated lignin preparation from the precipitated lignin.