Fabrication of a novel one-step coating hyper-hydrophobic fluorine-free TiO ₂ decorated hollow composite membrane for use in longer-term VMD with enhanced flux, rejection, anti-wetting and anti-fouling performances

Despite recent efforts, there are still significant challenges in preparing hyper-hydrophobic membranes using environmental-friendly materials and simple methods. In this work, using phase separation theory, we prepared a fluorine-free hyper-hydrophobic porous hollow composite membrane using one-step ultrasound dip-coating. Then, fluorine-free modified titanium dioxide, polydimethylsilane and polypropylene was used to construct the porous membrane with a water contact angle of 161°. The distribution of surface elements, morphology, wetting and the scale of titanium on the membranes was characterized using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), the water contact angle and acid-alkali stability, wetting resistance, and so on. The membrane was evaluated for desalination in the presence of organic-pollutants. Under longer-term vacuum membrane distillation, compared with the general polypropylene membrane, the flux of the hyper-hydrophobic membrane increased to 12.17 kg (m² h)^-1, and the rejection rate reached 99.99%. These results indicated that the free-fluorine hyper-hydrophobic membrane could be used for seawater desalination. Finally, our results indicate that the hyper-hydrophobic modified membrane has good potential for use in industrial desalination.