Bayer poisons: Degradation of Klason lignin in sodium hydroxide at 145 °C

Abstract

During bauxite refining, roots are dissolved in sodium hydroxide with the bauxite. This material is largely responsible for the poisoning activity of organic matter in the Bayer process. Although plant components are modified during extraction, they can be useful in demonstrating the role of different types of structural bonds during dissolution under bauxite refining. In this work, three Klason lignins have been prepared from Callitris rhomboidea plants (a gymnosperm) and the roots of Corymbia calophylla and Eucalyptus marginata (both angiosperms), and the dissolution of these materials in 3.5 M sodium hydroxide at 145 °C has been studied to understand β-O-4 aromatic carbon cleavage from sy..