Dual-layer PVDF and PVDF-HFP hollow fiber membranes synthesis for direct contact membrane distillation
Paper ID : 1417-MST2015-FULL
mehdi bahrami1, Javad Karimi-Sabet *2, seyed mohammad ali moosavian3, Abolfazl Dastbaz4
1School of Chemical Engineering, College of Eng., University of Tehran, Tehran, Iran
2NFCRS, Nuclear Science and Technology Research Institute, Tehran, Iran
3University College of Engineering, University of Tehran, Tehran, Iran
4Department of Chemical engineering, University of Tehran, Tehran, Iran
Membrane Distillation (MD) process is mainly investigates for desalination, stable isotope separation, waste water treatment and other applications which water is the major component present in the feed solution to be separates. Polyvinylidene fluoride (PVDF) and Polyvinylidene fluoride-hexafluoropropylene are the most used polymers for membrane distillation application. In this study two dual-layer hydrophobic-hydrophilic hollow fiber membranes (DLHF) were synthesis by dry/wet jet spinning phase inversion technique. Two cases were studied which hydrophilic layer (inner layer) of both was similar but the hydrophobic (selective) layer was different, i.e. PVDF and PVDF-HFP polymers. For synthesis of DLHF membranes, ethylene glycol (EG) was used as a pore formation agent and nanoclay particles as mechanical properties improvement in hydrophilic layer. The prepared membranes were characterized by scanning electron microscopy (SEM), liquid entry pressure (LEP), contact angel and porosity tests. SEM results showed that the structure of DLHF membranes was finger-like, the region between two layers was sponge-like and the layers of membranes have a good interfacial adhesion. The thickness and porosity of membranes were so closed together (PVDF-HFP: 210.275µm , 83.66% ; PVDF: 201.09µm , 82.83%). Contact angel of PVDF-HFP DLHF was 96.23º that was 5.18º more than PVDF DLHF. Finally, the fabricated DLHF membranes were tested for the direct contact membrane distillation (DCMD). In this study the DLHF membranes were compared and it was observed that the membrane with PVDF-HFP polymer in hydrophobic layer has slightly better properties and permeation flux than the other but the difference of polymers was not impressive.
Dual-layer hollow fiber membrane, Membrane distillation, PVDF-HFP, Phase inversion
Status : Paper Accepted (Oral Presentation)