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Water flux and hydrophobic durability play important roles in membrane distillation(MD) applications. Compared with the method of adsorbing nanoparticles by electrostatic adsorption, the surface roughness constructed by chemical bonding is more conducive to the performance of membrane. This paper reports a facile approach to fabricating superhydrophobic fluoroalkyl silane/polydimethylsiloxane@FeOOH@stabilized polyacrylonitrile(FAS/PDMS@FeOOH@SPAN) nanofibrous membrane(NFM) with outstanding hierarchical structures, aiming to achieve efficient and stable performance in MD. Electrospun polyacrylonitrile(PAN) membrane after peroxidation was chosen as the base membrane, followed by in-situ synthesis of iron oxyhydroxide and liquid-phase silanization. We tested the characteristics of FAS/PDMS@FeOOH@SPAN NFM in each preparation stage and its performance in direct contact membrane distillation(DCMD). The chemical bond between iron oxyhydroxide and the membrane is stronger, making the rough structure steady and dense. The FAS/PDMS@FeOOH@SPAN NFM exhibited a water contact angle of 155.4° and excellent hydrophobicity towards different pollutants. Besides, it showed satisfied properties with a water flux of 24.7 L·m−2·h−1, a high salts rejection of ca. 100% and an extended-term stability in DCMD using hypersaline water(10%, mass ratio). It is believed that this novel study proposes a universal and efficient method to fabricate a superhydrophobic surface and has great potential for high-salinity wastewater treatment in MD.

As a promising technology for water purification, solar desalination requires high maintenance to remove accumulated salt deposits; otherwise, the evaporation efficiency and functioning of the system will deteriorate. Here, we develop a facile auto-cleaning photo-thermal membrane for water desalination and illustrate its corresponding principles. The membrane is constructed by polypyrrole shells anchored onto cellulose fiber (PCF) paper and displays super-hydrophilicity, hydrostability and robust light absorption. In particular, the super-hydrophilic product with high porosity (80%) can stably bind abundant water and provide an efficient passageway to spontaneously transfer the scaled salt back to the bulk seawater in the dark. In addition, the PCF with abundant channels for water transport exhibited an extremely high light-to-vapor efficiency of 90% without sunlight concentration. With a high and constant evaporation flux of 1.41 kg m−2 h−1 (seawater salinity) over days of evaporation cycles without manual cleaning, the as-prepared photothermal membrane is expected to be competent for stable long-term solar desalination. In addition, it is easy to scale-up the production of this evaporator, with a low cost of approximately $ 1.33/m2. The present development, which is easy to scale-up, has a low cost, is highly efficient and features auto cleaning, is an important practical desalination technology.