Nanofilament-Coated Membranes with Enhanced Scaling and Biofouling Resistance for Membrane Distillation

Membrane distillation (MD) for water treatment can be applied in high salinity conditions and for treatment of wastewater. Current commercial membranes are made of fluorinated polymers such as polytetrafluoroethylene (PTFE). Here, porous membranes were coated with a silicone nanofilament layer to obtain a superhydrophobic and fluorine-free material. The classical coating procedure involves the use of toluene as a solvent. In this work, n-heptane was tested as a less toxic alternative. Different porous membranes were tested as the substrates of the nanofilament coating. The effect of acids, scaling solutions, and biofilm formation was analyzed in comparison to standard PTFE membranes. We demonstrate that superhydrophobic nanofilament-coated poly(ether sulfone) membranes (NF-PES) possess the required antiwetting properties for MD. Moreover, NF-PES membranes have static contact angles between 10 and 20° higher than PTFE standard membranes after immersion tests in solutions containing scaling substances, and biofilm grows from 20 to 50%, less in NF-PES than in PTFE.