Innovative hydrophobic coating of perfluoropolyether (PFPE) on commercial hydrophilic membranes for DCMD application

Innovative hydrophobic coated membranes have been prepared and characterised in Direct Contact Membrane Distillation (DCMD) for potential water treatment applications. A UV-curable perfluoropolyether (PFPE) hydrophobic compound (Fluorolink® AD 1700) was used as coating material to tailor the surface of commercial microfiltration hydrophilic polyamide (PA) membranes with different pore sizes. The coated membranes consisted of a top thin hydrophobic porous layer overlying the hydrophilic commercial membrane support. Produced membranes were fully characterised in terms of surface and cross-section morphology, water contact angle, porosity, pore size and liquid entry pressure. The innovative coated hydrophobic membranes were tested in DCMD configuration, using deionized water and salty solution 0.6 M (NaCl) as feed. In particular, the effect of the coating concentration on the permeate fluxes was investigated for different hydrophilic pore size commercial membranes (0.1–0.22–0.45 μm). The measured permeate fluxes ranged between 4.56–22.81 kg/m2 h at different feed temperatures (40–50–60 °C) keeping constant the permeate temperature at 14 °C, for deionized water, whereas an average value of 11 kg/m2 h, at 50 °C was found in case of the salty solution.