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Chitosan was used as environmentally friendly and bio-based scavenger for reducing the formaldehyde emission from medium density fiberboard. Using of chitosan powder showed better capacity of formaldehyde adsorption rather than the chitosan solution. Liquid 13C-NMR showed that the free formaldehyde in urea formaldehyde adhesive having chitosan powder was drastically reduced. Additionally, the observed peak at 155 ppm showed that that the chitosan powder was copolymerized with urea formaldehyde adhesive. Increasing the amount of chitosan powder was significantly reduced the emitted formaldehyde. It was shown that the formaldehyde adsorption of chitosan was strongly influenced by the pH value of adhesive composition. The pH value and the adhesive gel time tended to increase with addition of chitosan powder, due to the proton affinity of chitosan. The mechanical and physical properties of panels did not significantly change when the chitosan content as scavenger was raised up to 3%, while a formaldehyde emission class of wood level was achieved. It is supposed that the emission of formaldehyde might well increase again while the reactive sites of the chitosan added were already saturated with formaldehyde. Hence, performing of long-term formaldehyde emission is recommended for further analysis based on the obtained results in this study. [ABSTRACT FROM AUTHOR]