Emissions of sesquiterpenes from spruce sawdust during drying

Abstract

Large amounts of sawdust are dried to produce particleboard and pellets. During drying and densification, volatile organic compounds are emitted. These may contribute to the formation of tropospheric ozone. In this study, sesquiterpene emissions from Norway spruce sawdust dried in a continuous spouted bed at 140–200 °C have been investigated, and patterns of co-variation between sesquiterpene emissions and drying parameters have been elucidated. For sawdust dried to moisture contents suitable for pellets production, about 10–20 mg sesquiterpenes were emitted per kg oven dry sawdust. The sesquiterpene emissions amounted to about 20% of the monoterpene emissions. Drying at 200 °C caused markedly larger sesquiterpene emissions than did drying at 140 or 170 °C. The sesquiterpene emissions increased considerably at low wood moisture contents. While it has long been known that monoterpenes are emitted during the processing of wood, this study shows that sesquiterpenes are of considerable importance too.