Micro-nano chitosan for enhanced formaldehyde emission reduction in particleboards: a comprehensive study on gas emission characteristics and adsorption dynamics

Formaldehyde released from particleboard poses a serious threat to indoor air quality, and there is an urgent need to develop efficient adsorbents to reduce its release. This study introduces micro-nano chitosan (multiscale chitosan cross-linked polymers, MNCs) as a novel adsorbent, synthesized via ionic gelation and systematically characterized in terms of their specific surface area (0.301 m²/g), average particle size (19.96 μm), spherical morphology, and surface functional groups. The formaldehyde emission from particleboard treated with 3% MNCs was found to be reduced to 70.7% of that of the control group on day 28 by the 1 m³ climate chamber experiment, which was a significant emission reduction effect. The adsorption kinetic analysis showed that the adsorption of formaldehyde by MNCs conformed to the pseudo-second-order adsorption kinetic model, and its chemical adsorption mechanism was attributed to the Schiff base reaction between the amino group on the chitosan ring and formaldehyde. In the C-history experiment, the C_m0 of control panel was measured to be 1.94 × 10⁵ mg/m³ and D_m to be 2.7 × 10⁻⁸ m²/s, whereas after treatment with 3% MNCs, the C_m0' was reduced to 0.29 × 10⁵ mg/m³, the D_m' was reduced to 4.31 × 10⁻¹⁰ m²/s and the partition coefficient K was enhanced from 243.9 to 855.5 in the original panels, indicating that the addition of MNCs significantly inhibited the diffusion of formaldehyde, enhanced the retention capacity of formaldehyde in the particleboards, and reduced the initial volatilizable formaldehyde reserves. This study provides theoretical basis and experimental support for the application of MNCs in the pollution control of wood-based panels, whose efficient emission reduction performance originates from the unique nanoporous structure and the active amino sites in chitosan molecules.