The kraft lignin characteristics of areca leaf sheath isolated by phosphoric acid

Abstract

This study reported on lignin extraction from the Areca leaf sheath (ALS) by boiling treatment before kraft pulping. OFAT (one factor, one time) was designed to determine the optimal pulping condition for the highest delignification selectivity (DS). On that optimum condition, lignin was precipitated from black liquor by 20 % phosphoric acid. The 22 % active alkali and 22 % sulfidity were the optimal conditions. The lignin was then characterized by the morphological, chemical, and thermal properties and particle size. Isolated lignin has similar functional groups to reference lignin with purity and yield of 62.7 % and 12.27 %. The thermal analysis of lignin resulted in a char residue of 30.2 % with a glass transition temperature (Tg) of 117.34 °C. The lignin has an irregular or non-uniform form in micron size. A low equivalent weight of lignin indicates its prospect as an adhesive or an adhesive filler for panels.