Adsorption-assisted transport of water vapour in hydrophobic PVDF/graphene composite membranes

Recently, graphene-based membranes have attracted considerable attention for water treatment and purification processes. Therefore, the objective of this research was to use graphene as a filler to enhance the polyvinylidene fluoride (PVDF) membranes performance and to investigate the effect of graphene filler in water vapour transport in direct contact membrane distillation process. Superhydrophobic microporous membranes were prepared with different graphene loading and have been tested in a thermally driven desalination plant and the results have been compared to those achieved for conventional membranes worked under analogous conditions. The fluorinated surface, micro-thickness together with a large number of small-shaped pores provided the novel membrane with durable anti-wetting properties as well as outstanding mechanical and chemical stability over time. Remarkably, no thermal polarization is observed but rather adsorption assisted mechanisms in the composite membrane affect the transport efficiency in a membrane distillation configuration. This study shows a significant improvement of performance in terms of transport and salt rejection with respect to the pristine PVDF membrane and provides new insight about the role of embedded graphene in polymer membranes.