Preparation of silane-free porous structure hyperelastic phosphorylated chitosan sponge reinforced with bamboo activated carbon and its efficient PM2.5 removal

Chitosan (CS) based sponge shows important potential applications in adsorption, filtration, sensing, etc., which often requires good deformation-recovery ability that is usually achieved under the help of silane elastomers. Herein, a simple but innovative strategy was proposed that only bamboo activated carbon (BAC) was employed as the reinforcer to construct highly elastic phosphorylated chitosan (P-CS) sponge with through-hole structure like layer-support by freeze drying. In the system, the through-hole structure like layer-support was formed by directional freezing, where BAC as the "support" was fixed onto the P-CS "layer". When the through h-hole structure like layer-support is squeezed, the "support" could limit the bending of the "layer" and protect it to some extent. Therefore, the resulting P-CS/BAC composite sponge displays excellent elastic properties. Based on the through-hole structure, the P-CS/BAC composite sponge is well suited for PM2.5 filtration, achieving a filtration efficiency of 99.61 % and a low pressure drop of only 60 Pa. Besides, it has excellent flame retardance (LOI of 50.4 %) due to the synergistic effect of N and P of P-CS. The system could achieve highly elastic without any silane, meanwhile, its simple preparation and excellent performance endow it a great development prospect in air purification.