Catalytic Modification and Photo-Stabilization of Lignin Functional Groups

Abstract

The primary components of wood, the main raw material used for papermaking in North America, are the fibrous, hydrophilic carbohydrates (cellulose and hemicelluloses) and the three-dimensional, hydrophobic lignin. For the purpose of making papers, wood, either in the form of wood chips or sawmill residues, must first be reduced to pulps (discrete fibres) by a chemical or mechanical pulping process.1 In chemical pulping, pulps are produced in a yield of 45–55% through the dissolution of lignin by the pulping chemicals at an elevated temperature (≥ 160 °C). In mechanical pulping, pulps are formed in a yield of 90-98% through the action of mechanical forces that separate the fibres but retain lignin. From 1980 to 1999, the world mechanical pulp production has increased steadily from 27.6 to 35.1 million tonnes, accounting for ~ 23% of the total world wood pulp production.2 Such a steady increase is expected to continue because of the low cost and high efficiency in material usage involved in the production of mechanical pulps. Indeed, as far as the pulp and paper industry is concerned, one of the most profitable uses of lignin is to use it as a component of pulps and papers.3