Water desalination under one sun using graphene-based material modified PTFE membrane.

Harvesting solar energy for water desalination is considered as one of the most important technologies to effectively address global water scarcity. Recently, it was found that water droplets on azobenzene modified anodized alumina membranes and disperse red 1 modified PTFE (polytetrafluoroethylene) membranes can permeate the membrane to be purified and desalinated under light irradiation. Herein, in order to efficiently collect vaporized and condensed water, we demonstrated the immobilization of graphene-based material n hydrophobic PTFE membrane surface for water desalination via photothermal membrane distillation (PMD). An ultrathin graphene-based film, fabricated by a scalable process, serves as efficient solar absorbers (absorption efficiency of rGO/pDA-rGO > 80%), ultrafast water permeable channels, and high salt resistance network. Compared with bare PTFE membrane, water transmembrane flux on the pDA-rGO material modified PTFE membrane can achieve as much as 78.6% enhancement under normal solar illumination. Due to high salt rejection of graphene-based films, the evaporation rate of graphene-based material modified PTFE membrane was unaffected by 4% NaCl solution, which indicated that concentration polarization effect can obviously be eliminated. These results provided new insights into the design and utilization of graphene-based films for effectively solar desalination via PMD. [ABSTRACT FROM AUTHOR]