Porous polyvinylidene fluoride-co-hexafluropropylene (PVDF-HFP) hollow fiber membranes were fabricated through a wet spinning process. In order to improve the membrane structure

composition of the polymer solution was adjusted by studying ternary phase diagrams of polymer/solvent/non-solvent. The prepared membranes were used for sweeping gas membrane distillation (SGMD) of 20 wt% ethylene glycol (EG) aqueous solution. The membranes were characterized by different tests such as N

2

permeation

overall porosity

critical water entry pressure (CEP

w

)

water contact angle and collapsing pressure. From FESEM examination

addition of 3 wt% glycerol in the PVDF-HFP solution

produced membranes with smaller finger-likes cavities

higher surface porosity and smaller pore sizes. Increasing the polymer concentration up to 21 wt% resulted in a dense spongy structure which could significantly reduce the N

2

permeance. The membrane prepared by 3 wt% glycerol and 17 wt% polymer demonstrated an improved structure with mean pore size of 18 nm and a high surface porosity of 872 m

-1

. CEP

w

of 350 kPa

and overall porosity of 84% were also obtained for the improved membrane. Collapsing pressure of the membranes relatively improved by increasing the polymer concentration. From the SGMD test

the developed membrane represented a maximum permeate flux of 28 kg·m

-2

·h

-1

which is almost 19% higher than the flux of plain membrane. During 120 h of a long-term SGMD operation

a gradual flux reduction of 30% was noticed. In addition

EG rejection reduced from 100% to around 99.5% during 120 h of the operation.