Fibrous residues of palm oil as a source of green chemical building blocks

Abstract

Oil palm is an important industrial crop, and is usually harvested to obtain lipids and proteins. However, such biomass can be a source of important chemical biomacromolecules with several industrial applications. The aim of this work was to extract cellulose nanocrystals (CNC), cellulose nanofribrils (CNF), and lignin from pressed oil palm mesocarp fibers (POPMF). Initially, fibers were acetosolv pulped, resulting in two fractions: a lignin-rich black liquor and cellulose-rich pulp. Lignin was recovered from the black liquor and totally chlorine-free (TCF) bleaching was applied to purify the cellulose. Fibers and biomacromolecules were characterized using several methods including SEM, FEG/SEM, TEM, DRX, GPC, zeta potential, TGA, and FTIR. The pulping-bleaching treatment improved the amount of crystalline cellulose in the pulp, yielding CNC with good thermal stability, a length of 289nm, diameter of 11nm, and an aspect ratio of 26. The lignin presented a high purity, with a syringyl-rich structure and good thermal stability. Such characteristics highlight the potential use of POPMF lignin as a green building-block and POPMF nanocellulose materials as renewable biomaterials.