A novel photothermal composite membranes for solar pervaporation desalination

Abstract

Pervaporation (PV) technology, which combines heat treatment with membrane separation, has emerged as a promising desalination process due to its high unipolar separation rate and energy efficiency. However, traditional pervaporation systems necessitate the heating of the feed solution to establish a vapor pressure differential across the membrane, leading to significant energy consumption. In contrast, solar energy offers a clean and abundant resource, making its integration with pervaporation an effective approach to achieve desalination at a lower energy cost. In this study, carbon nanotubes (CNTs) and graphene nanosheets (GNSs) are utilized as efficient photothermal conversion materials. We developed innovative photothermal composite membranes based on polyvinyl alcohol (PVA) blended with CNTs or GNSs (PVA-CNTs/PVA-GNSs), which were subsequently incorporated into a novel solar pervaporation (SPV) system. In this SPV system, the feed solution is heated by solar radiation that is absorbed by the CNTs/GNSs on the membrane's surface, significantly reducing the energy costs associated with the system. Experimental results demonstrate a remarkable membrane flux of 3.02 kg/m²·h, indicating that this novel SPV system outperforms many previously reported solar desalination systems. This study establishes a foundation for low-energy SPV desalination and provides a promising pathway for developing practical desalination applications utilizing pervaporation technology.