Fabrication of modified PVDF membranes with PAA network polymer for highly efficient oil/water emulsion separation

Dip coating technology is often used for hydrophilic modification of PVDF membrane surfaces due to its significant modification effect, simple process and low cost. Nevertheless, the relatively feeble binding forces between coating molecules and between the coating and the substrate membrane often raise concerns about the stability of modified membranes. This study utilized PAA and Sac-100 to develop a hydrophilic and negatively charged coating to improve the anti-fouling characteristics of PVDF membranes in the process of oil/water separation. Two modification reagents underwent ring opening crosslinking reaction and ultimately deposited on the surface of PVDF membranes in the form of a network polymer, thereby solving the stability problem of the modification coating. After the modification, the surface microstructure of the membranes remained unchanged, while the average pore size fell from 0.37 mu m to 0.32 mu m. The water contact angle of the modified membrane decreased to 39 degrees suggesting an excellent hydrophilic property. The modified PVDF membrane exhibited exceptional resistance to fouling in the oil/water separation experiment, demonstrating a consistent permeance value of 212 L m- 2 h- 1 bar- 1 that was four times higher than that of the original membrane. Following the cleaning process, the permeance of the modified membrane could be restored to a level of 74.5 %.