Formaldehyde adsorption capacity of chitosan derivatives as bio-adsorbents for wood-based panels

Abstract

Chitosan and its derivatives (grafted chitosan and chitosan nanoparticles) were used as bio-based adsorbents in urea-formaldehyde (UF) resins, and accordingly, their effects on the curing behavior, resin structure, crystalline structure, and formaldehyde emission (FE) of final resin has been investigated. Synthesis of grafted chitosan and chitosan nanoparticles was confirmed by FTIR spectroscopy. Characteristics of UF resins were monitored by 13C NMR and X-ray diffraction. This analysis showed that the free formaldehyde and crystallinity of UF resin having chitosan-based adsorbents were substantially reduced. The FE was largely decreased in the medium density fiberboard (MDF) containing chitosan nanoparticles (60%), followed by grafted chitosan (34%) and chitosan powder (22%). A FE class of F**** (<0.3 mg/mL) was obtained by addition of only 1% chitosan nanoparticles (0.21 mg/L). Unexpectedly, increasing the amount of chitosan nanoparticles conversely raised the formaldehyde emission from MDF. The mechanical and physical properties of panels were not significantly changed with the addition of chitosan-based adsorbents.