Salt-resistant and antibacterial polyvinyl alcohol/chitosan/silver-loaded graphene oxide electrospun nanofiber membrane for high-efficiency solar-driven desalination

Abstract

To address the issues of low photothermal conversion efficiency, salt deposition and biological contamination in solar-powered desalination, we have developed nanofibrous membranes composed of an optimized ratio of silver-loaded graphene oxide (GO-Ag) composites and polyvinyl alcohol/chitosan (PVA/CS), using a simple and productive electrospinning technique. The synergistic effect of GO and Ag significantly enhanced the photothermal conversion efficiency of the dual-photothermal PVA/CS/GO-Ag-4% electrospun nanofiber membranes (EFMs), which achieved the pure water evaporation rate of 1.67 kg m−2 h−1 and photothermal conversion efficiency of 93.3% under 1 sun (1 kW m−2). Notably, 97% of optical energy is converted to heat when the PVA/CS/GO-Ag-4% EFMs were placed on a homemade evaporation device, achieving up to a simulated seawater evaporation rate of 1.64 kg m−2 h−1 under 1sun, with a desalination rate of 99.99%. More importantly, larger area EFMs are easier to prepare compared to other morphologies of solar evaporators, and larger membranes can be placed on outdoor evaporation units for large-scale effective desalination of seawater used to collect fresh water under natural light. Furthermore, PVA/CS/GO-Ag-4% EFMs exhibited outstanding antibacterial performance against Escherichia coli and Staphylococcus aureus. Considering these strengths, the PVA/CS/GO-Ag-4% EFMs has considerable application potential in solar-driven desalination to solve water crises.