Emission of Volatile Organic Compounds from Heat-Treated Scots Pine Wood As Affected by Wood Drying Method: Results Obtained with Olfactory Machine and Headspace Gas Chromatography-Mass Spectrometry

Due to the use of heat-treated wood products like ThermoWood (R), even for indoor applications, the type and amount of volatile organic compounds (VOCs) emitted from the products are essential for indoor air quality and human health. The drying method of wood applied as the first step in the ThermoWood (R) production process may influence this property. In this study, the effects of radiofrequency/vacuum (RF/V) drying technology in comparison with conventional kiln drying at a mild and normal temperature on the emission of VOCs from Scots pine ThermoWood (R) were investigated using Headspace Gas Chromatography-Mass spectrometry (HS-GC-MS) and olfactory system (electronic nose). An olfactory machine consisting of 6 metal oxide semiconductors (MOS) sensors were used for this purpose. Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) were applied to classify and analyze the data of olfactory signals. Results showed that emission of VOCs was higher in the samples dried by RF/V technology and was mainly consisted of terpenes, aldehydes, and alcohols. Acids were identified as the main VOCs in the ThermoWood (R) produced from RF/V dried wood. The emission of some VOCs, such as terpenes, was reduced after thermal modification. Overall, it can be concluded that the type and the amount of VOCs of ThermoWood (R) are influenced by the drying method of wood applied before starting the thermal modification.