Characterization of VOC emission profile of different wood species during moisture cycles

Abstract

This study addresses the characterization of volatile organic compounds (VOCs) emitted by samples of 13 different wood species, belonging to both softwoods and hardwoods groups, regularly measured at different intervals of time, after the first measurement on green wood. The same wood specimens were subjected to several cycles of water desorption and adsorption, assuming that moisture variation might play a role in both the formation and emission of VOCs. Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-TOF-MS) was used as a tool to characterize the emission of VOCs. Coupled with a multivariate class-modelling approach, this tool was able to discriminate between groups (softwood and hardwood) and in some cases between different species. However, results showed that the discriminant capacity of VOCs emission to separate species and families rapidly decreases after the first cycles of moisture variation in wood. The green wood was characterized by a richness of volatile compounds, whereas, after only the first dry cycle, wood emitted a more restricted group of compounds. We hypothesized that most of these VOCs might have originated from structural changes and degradation processes that involve the main polymers (particularly hemicellulose) constituting the cell wall of wooden cells. The results obtained are in agreement with the physical and chemical modification processes that characterize wood ageing.

The effects of paints and moisture content on the indoor air emissions from pinewood ( Pinus sylvestris ) boards

“…However, this should result in higher emissions after the moisture equilibrium has been reached but the TVOC emissions from wood with 16% MC decreased throughout the study. Additionally, previous studies indicate that moisture cycles reduce and modify VOC emissions, especially terpene emissions, from different wood species, which is in line with our results 44 …”

Evaluation of the seasonal variation of VOC surface emissions and indoor air concentrations in a public building with bio-based insulation

“…In the study of Maskell et al, wood fiber emitted high concentrations of acetic acid [18]. This VOC may come from the cleavage of acetyl groups of the hemicellulose, while aldehydes mainly originate from the oxidative decay of cellulose and lignin present in the wood [42].…”

Characterization of Odors of Wood by Gas Chromatography-Olfactometry with Removal of Extractives as Attempt to Control Indoor Air Quality

“…Although many of the VOCs are not odorous in nature, a broad overview of the volatiles hitherto detected in diverse woods offers insights into prospective main odor-active candidates that contribute to wood odor [ 11 ]. Therefore, numerous studies have been carried out for identification of the specific class of extractives [ 12 , 13 , 14 , 15 , 16 ]. However, not all VOCs contribute to odor because it depends on whether the concentration of the VOC is higher than the human threshold odor concentration [ 2 ].…”