Construction of chitosan/phosphorylated cellulose nanofibrils based aerogel for dual-effect air purification.

PM2.5 particles and formaldehyde can cause irreversible harm to the human body. Therefore, the development of materials for removing PM2.5 and formaldehyde has always been valued. Herein, a charge synergy strategy is proposed to enhance the air purification performance and supply charge to the skeleton, thereby reducing the damage to the mechanical properties of the materials caused by negatively charged functional additives. This strategy constructs a common aerogel skeleton of chitosan and phosphorylated cellulose nanofibrils (CS/PCNF) with negative charges by freeze-drying to reduce the addition amount of bamboo activated carbon (BAC). Furthermore, the introduced PCNF uniformly disperses BAC particles through the negative charge carried by the dissociation of the phosphate group. The prepared CS/PCNF/BAC1 aerogel has excellent compressive strength (10.0 kPa) and good compressibility (the height loss after 50 % deformation is only 4.5 %). Not only that, through the synergy of physical interception and electrostatic adsorption, the aerogel demonstrates an excellent filtration efficiency for PM2.5 (96.44 %) and a low pressure drop (58 Pa), as well as a good adsorption capacity for formaldehyde (23 mg/g) after 6 h. Furthermore, even at high temperatures (200 °C) and high flow velocity (15 cm/s), the aerogel still exhibits a filtration efficiency of 94.55 % (pressure drop of 103 Pa) and a filtration efficiency of 90.89 % (pressure drop of 69 Pa), respectively. Furthermore, all the materials used are biomass materials, and it is expected to provide a new approach for designing sustainable air purification materials.