Novel solar membrane distillation enabled by a PDMS/CNT/PVDF membrane with localized heating

Abstract

Membrane distillation as a means of seawater desalination using solar energy has the potential to help address the challenges associated with the water-energy nexus and reduce energy consumption. However, the development of an efficient, scalable, stable, and sustainable novel solar membrane distillation (SMD) process remains challenging due to the limited number of membrane preparation procedures and system designs. This work, inspired by solar-driven interfacial evaporation, describes an SMD process employing a hydrophobic trilayer membrane and a two-level SMD structure for effective seawater desalination. A polydimethylsiloxane/carbon nanotube/poly(vinylidene fluoride) (PDMS/CNT/PVDF) membrane, prepared by electrospinning and spraying, exhibited broad light absorption, good photothermal conversion, and localized heating of seawater. The novel two-level SMD structure effectively reused the condensed heat and ensured a greater temperature difference for interfacial evaporation and steam transport, thereby improving fresh water productivity. The greatest productivity (1.43 kg m−2 h−1) and salt rejection (99.9%) were achieved under 1 kW m−2 of solar illumination. This low-energy SMD system using solar energy is suitable for emergency water production and offshore seawater desalination.