Emission characteristic of OVOCs, I/SVOCs, OC and EC from wood combustion at different moisture contents

Wood combustion is an important source of organic compounds, and its emission characteristics are affected by many factors, among which fuel moisture content (MC) is poorly understood. In this study, wood with MC of 2.5%, 10.9%, 19.2%, 31.4%, and 43.2% were prepared by stepwise dehydration of fresh pine, and burned separately in a quartz tube furnace at different ignition temperatures (400, 600, and 800 °C), in order to discuss the effects of MC on the emission characteristics of gas- and particle-phase organic compounds. The results showed that the effects of MC on the emission factors (EFs) of organic compounds were significant. When MC was close to 10%, the average EFs of carbonyl compounds (CCs), intermediate volatile organic compounds (IVOCs), polycyclic aromatic hydrocarbons (PAHs), n-alkanes, organic carbon (OC), and elemental carbon (EC) were 832.0 ± 518.5, 439.3 ± 111.6, 44.3 ± 6.6, 59.3 ± 9.3 mg/kg, and 2.4 ± 0.2, 0.8 ± 0.8 g/kg, respectively whereas when MC was near 30%, all the EFs reached the maximum and were 2.4, 3.1, 2.6, 4.2, and 3.1 times the lowest values, respectively. The MC and ignition temperature together affected the composition of organic compounds, with different organic profiles observed at various MCs when the temperature increased from 400 to 800 °C. For example, at MC ≈ 10%, the proportion of unresolved complex mixture (UCM) in IVOCs decreased from 59.7% to 43.4%, while the proportion of 5-6-ring PAHs increased from 7.4% to 35.4%. However, at MC ≈ 30%, formaldehyde and acetaldehyde in CCs decreased from >60% to ∼40%. In brief, the influence of MC may explain to a large extent the differences in organic emission characteristics of wood burned in the stove and open burning, and MC should be further considered in the experiments on the measurement of organic compound emissions from biomass burning.