Fractionation and characterization of construction and demolition waste wood

Abstract

The valorization of construction and demolition (C&D) waste wood offers a sustainable avenue for meeting the increasing demand for renewable lignocellulosic resources in a circular bioeconomy. This study examines the physicochemical properties and fractionation behavior of C&D wood waste, comprising mixed softwood (MW), particleboard (PB), and fiberboard (FB), via three delignification strategies: acidic (acetic and formic acids), alkaline (sodium hydroxide), and neutral (ethanol-water) pulping. Compositional, structural, and thermal analyses of the raw materials revealed minor variations across the wood categories. Similar analyses of the resulting pulps showed that neutral and acidic treatments yielded better-preserved pulps in terms of compositional integrity and thermal performance, while alkaline pulping produced lower yields and the poorest pulp quality. Both acidic and neutral processes achieved high yields of pulp and lignin, with the neutral method producing lignin of the highest purity, thermal stability, and reactivity, as well as the lowest molecular weight. In contrast, lignin from the alkaline treatment exhibited the lowest purity and thermal stability. Acidic-extracted lignin had the highest molecular weight and moderate performance in other metrics. UV–visible spectrophotometry revealed predominantly non-conjugated phenolic structures in lignins from neutral and acidic treatments, whereas alkaline lignin contained conjugated phenolic structures.