Patent ID: 6420533
Filing Date: 2002-07-16
Classification: C08H

Abstract:
A method to produce depolymerized lignins substantially free from sodium compounds, which comprises:providing a mixture of depolymerized lignins dispersed and dissolved in a solution containing sodium hydroxide, and providing a means for separation of depolymerized lignins from a solution containing sodium hydroxide, and separating said depolymerized lignins from said solution containing sodium hydroxide to provide an solution containing sodium hydroxide and the separated depolymerized lignins, and extracting with water the depolymerized lignins containing water soluble sodium compounds to provide an extractate containing water soluble sodium compounds and a rafinate containing depolymerized lignins, and combining said solution containing sodium hydroxide with said extractate to form a sodium hydroxide solution, and concentrating said sodium hydroxide solution by removal of water by a multiple-effect evaporator to concentrate the sodium hydroxide solution, and combining an acid with the heretofore extracted depolymerized lignins to produce water soluble sodium salts to form a phase of water soluble sodium salts and a phase containing depolymerized lignins substantially free of sodium compounds, and separating said depolymerized lignins phase from said water soluble sodium salts phase to yield depolymerized lignins substantially free of sodium compounds and a solution of water soluble sodium salts whereby depolymerized lignins substantially free of sodium compounds and a solution of concentrated sodium hydroxide suitable for reuse to depolymerized, disperse and dissolve additional lignins are created.