Development of a novel perfluoropolyether (PFPE) hydrophobic/hydrophilic coated membranes for water treatment

A novel method to prepare hydrophilic/hydrophobic membranes via dip-coating and UV in situ polymerization was presented. Fluorolink ® MD700, a UV-curable perfluoropolyether (PFPE) hydrophobic compound, was employed as surface modifier via coating technique on two different commercial hydrophilic membranes with different pore size (0.1-0.2-0.45 μm): polyamide (PA), and polyethersulfone (PES). The influence of starting membrane material (PA-PES) was studied and all coated membranes were characterized in terms of surface morphology, water and oil contact angle, porosity, pore size, liquid entry pressure and mechanical tests. The coating resistance and stability in time with salty solution NaCl 0.6 M and chemicals cleaning agents, such as KMnO 4 0.1 wt%, Hypochlorite NaClO pH 4.25, HCl pH 2.5, NaOH pH 11.5, were evaluated. Membranes performance was tested in direct contact membrane distillation (DCMD) configuration, using deionized water and salty solution 0.6 M (NaCl) as feed. The effect of the starting material on the permeate fluxes was investigated. The measured permeate water fluxes ranged between 3 and 22 kg/m 2 h and 2.9–19.5 kg/m 2 h for PA and PES respectively, at different feed temperatures (40–60 °C). Both flux (∼8.3 kg/m 2 h) and salt rejection (∼99.95%) were kept constant during a prolonged test (158 h) carried out at 50 °C on the coated PA 0.45 μm membrane.