Poly(vinylidene fluoride) hollow fiber membrane for high-efficiency separation of dyes-salts

A poly(vinylidene fluoride) hollow fiber membrane (HFM) was fabricated through a simple, fast (one-step), and inexpensive procedure to separate dyes and salts (sodium sulfate, sodium chloride) in textile wastewater. Scanning electron microscopy images of the HFM indicated that a neat hollow structure was obtained through a single shot spinneret. Moreover, the finger-like and sponge-like structure of the HFM had a hierarchical structure. The optimized HFM had a molecular weight cut off of 6798 Da and an isoelectric point of 3.8. Charge of the HFM was greater than −50 mV when the pH was higher than 6. The HFM displayed a pure water flux of 13.51 L/m2 ·h· bar, and rejection of 100% to Congo red at a dye concentration of 50 ppm and operation pressure of 0.2 MPa. The membrane also showed excellent stability and antifouling property during long-term operation with a mixture of dyes and salts. The HFM displayed efficient and stable separation performance for separation of salts and dyes, which would be of great significance for the reuse of textile wastewater.