A new superhydrophobic polypropylene hollow fiber membrane preparation method and its application in the treatment of brine with high salt concentration

Abstract

A simple and effective strategy combining etching, electrostatic adsorption, and dip-coating methods was developed in this paper to prepare uniform and stable superhydrophobic surfaces on polypropylene hollow fiber membranes (PPHFM) for desalination of highly concentrated salt solutions (3.5 wt% − 15 wt%). A number of appropriate evaluation methods were used to characterize the membrane, and the results confirmed that the composite membrane was successfully modified. Compared with PPHFM, the water contact angle (WCA) was increased from 119° to 165°; the surface roughness was increased from 0.198 µm to 0.961 µm; the mean pore size was increased from 0.16 µm to 0.24 µm; the porosity was increased from 53% to 70%. The PPHFM and composite membranes were applied to a long-term (80 h) vacuum membrane distillation (VMD) with a salt concentration of 15 wt%. The average permeates flux of the composite membrane increased from 4.27 kg (m2 h)−1 to 12.33 kg (m2 h)−1 compared to the PPHFM, while the composite membrane had superior resistance to wetting and stability.