Environmentally-friendly halloysite nanotubes@chitosan/polyvinyl alcohol/non-woven fabric hybrid membranes with a uniform hierarchical porous structure for air filtration

Abstract An environmentally-friendly halloysite nanotubes@chitosan/polyvinyl alcohol/non-woven fabric (HNTs@CS/PVA/NWF) hybrid membrane with a uniform hierarchical porous structure for air filtration was prepared using a developed dip coating method combined with nonsolvent induced phase separation (NIPS) and the surface deposition of HNTs. Additionally, a TiO2/H2O2 photocatalysis approach was developed to improve the hydrophilicity of the polyester NWF. It was found that the porous CS/PVA blend was embedded into the NWF to frame a reinforced composite membrane with an intact polymer membrane. The results showed that the structure and properties of the resultant membranes were closely related to the thickness of the casting solution and the presence of HNTs. The filtration efficiency (FE) and pressure drop (PD) of the resultant membranes under a face velocity of 5.3 cm s−1 were 96.8% and 143.9 Pa, respectively. The filtration performance was mainly attributed to the direct interception on the membrane surface as well as the strong interactions and diffusion adsorption caused by the CS/PVA matrix and HNTs, respectively. Furthermore, the antibacterial rate of the resultant membranes reached to 99.6% for E. coli and 99.1% for S. aureus due to the synergistic effects of the CS component and the sensitized TiO2 nanoparticles.