(146f) New Insights Into Hydrophobic/Hydrophilic Composite Hollow Fibers for Direct Contact Membrane Distillation

Hydrophobic/hydrophilic composite membrane is a new design of membrane in terms of structures and materials for DCMD. With dry-wet phase inversion process, a novel type of hydrophobic/hydrophilic hollow fiber membranes was fabricated in this research. The outer layer was made from polyvinylidene fluoride (PVDF), while the inner layer PVDF and polyvinyl alcohol (PVA) blend. Effects of dope composition, PVA/PVDF blending ratio and coagulants on the morphological, physiochemical and mechanical characteristics of the membranes thus generated were investigated. The pore size and porosity in respective layer of the dual-layer membranes were determined mainly by data obtained from SEM and corresponding software processing. The DCMD performance observed in experiments was compared with that obtained by mass and heat transport modeling of both single-layer and dual-layer DCMD membrane. Analysis relating the membrane structural features and the above comparison revealed that the inner layer characteristics in terms of both material hydrophilicity and pore size should be optimized to give a better membrane performance. The maximum flux in DCMD obtained was around 24.4kgm^-2h^-1 at 65℃.