Effect of CaCO3 and/or polyaluminium chloride (PAC) treatment on the main components in prehydrolysis liquor of Whangee dissolving pulp

Abstract

Lignin removal is essential for the value-added utilization of hemicelluloses in the prehydrolysis liquor (PHL) of a kraft-based Whangee (a genus of bamboo) dissolving pulp production. In this work, a novel process concept was proposed for a calcium carbonate (CaCO3) treatment of PHL. The results revealed that the optimum dosage of an individual system of CaCO3 and polyaluminium chloride (PAC) treatment was 1.7% and 16.0%, at which the total sugars retention was 95.7% and 94.4%, the acid-soluble lignin removal 6.09% and 9.29%, and the acid-soluble lignin selectivity 58.6% and 62.4%, respectively. Alternatively, CaCO3 and 16.0% PAC were employed in a dual system to remove the lignin. Dual vs. individual system results showed that the highest total sugars retention (97.3%) and acid-soluble lignin selectivity (77.5%) occurred at the optimum dosage (2.0%/16.0%) of a dual CaCO3/PAC system, and the highest mannose (84.2%) and glucose retention (96.5%) with a dual system of 1.0%/16.0% CaCO3/PAC. Additionally, in the dual system, the adding order of 1.0% CaCO3 and then 16.0% PAC showed that 1.0%/16.0% CaCO3/PAC was more effective than 16.0%/1.0% PAC/CaCO3.