Biologically inspired silk fibroin grafted polyacrylonitrile filtration membrane prepared in ZnCl2 aqueous solution

In this study, biologically inspired silk fibroin grafted polyacrylonitrile (SF-g-PAN) filtration membrane was prepared using ZnCl₂ aqueous solution as solvent, avoiding the use of organic solvents. Phase inversion occurred when Zn²⁺ and Cl^- ions gradually diffused into water, creating a well-connected ion channel network and the SF-g-PAN filtration membrane was obtained. The membranes were observed by SEM and 3D ultra-depth microscope. The hydrophilic property, pore size distribution and dye rejection of the membrane were investigated. Results showed that the membrane has no finger hole formation because ZnCl₂ aqueous solution has a lower curing rate parameter compared with organic solvents. SF-g-PAN membrane possessed good anti-fouling properties and pH sensitivity. The pore size distribution of the SF-g-PAN membrane was 0.25-1.04 nm. The rejection of direct yellow 27 (Mw=662.6) and amaranth (Mw=604.5) was 96.51% and 30.63%, with the flux of 72.32 L m^-2 h^-1 and 73.83 L m^-2 h^-1 respectively at 0.1 MPa. The SF-g-PAN membrane has a wide range of applications prospect in fine separation, dye desalination, waste water treatment and biomedical fields.