An integrated process for removing the inhibitors of the prehydrolysis liquor of kraft-based dissolving pulp process via cationic polymer treatment

Abstract

The prehydrolysis liquor (PHL) of the kraft-based dissolving pulp production process contains various amounts of hemicelluloses that can be utilized in the production of value-added products. In this work, a new process was proposed for removing the inhibitors of PHL via employing a flocculation concept to facilitate the utilization of hemicelluloses. Lignin, lignocelluloses/cationic polymer complexes, and possibly ethanol are the main products of this process. This process has been experimentally evaluated with an industrially produced PHL and cationic polymers. The results showed that 16% of lignin, 19% of acetic acid, 43% of furfural, and insignificant amount of sugars were removed from PHL via pretreating PHL with acid and lime at pH 7. Furthermore, by adding 0.4–0.5 mg g⁻¹ polydiallyldimethylammonium chloride (PDADMAC) or chitosan to the pretreated PHL, 12–14% acetic acid, 40–50% furfural, 5–6% monomeric sugars, and 25% oligomeric sugars were removed from the PHL. The complexes made from these components may be applied as organic fillers in various industries. Alternatively, by adding 1.2 or 1.4 mg g⁻¹ PDADMAC or chitosan to the pretreated PHL, 30 or 35% of lignin was removed, respectively, which induced complexes that could be used as a fuel source. The composition of the complexes formed was also determined in this work. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 28: 998–1004, 2012