Development of non-woven fabric-based ECTFE membranes for direct contact membrane distillation application

In this work, a lower melting point of HALAR® Ethylene-Chlorotrifluoroethylene (LMP ECTFE) was used to prepare non-woven fabric-based porous membranes, using a polyester non woven (NWPET) as support, via dip-coating. Di-ethyl Adipate (DEA) and di-ethylene Glycol (DEG) were selected as primary and secondary diluent, respectively. SEM analyses showed that in all cases the coating layer was homogeneous, covering all the NWPET support and leading to an interconnected sponge-like microstructure. Membrane characterization evidenced the effects of the DEG concentration, which plays the role of pore former. The effect of the immersion time was examined and studied, too. The produced membranes were fully characterized in terms of water contact angle, porosity and pore size. Direct contact membrane distillation (DCMD) experiments using water and salty solution 0.6 M (NaCl) as feed, were performed for selected supported membranes. The obtained fluxes ranged between 3 and 22 kg/mh, depending on DEG concentration, at the same immersion time, and on the feed temperatures (40-60 °C). Rejection (R%) was comprised from 94.95 to 99.82%. In particular, the N-ECTFE 7-0-7 membrane, with the highest R%, showed a stable deionized water flux before and after the experiments, indicating its ability to recover its original performance.