Highly-efficient and salt-resistant CsxWO3@g-C3N4/PVDF fiber membranes for interfacial water evaporation, desalination, and sewage treatment

Abstract

Abstract In this work, cesium tungsten oxide/graphitic carbon nitride (Cs0.32WO3@g-C3N4) hybrids were successfully synthesized using a facile solvothermal method. The hybrids were incorporated into PVDF and electrospun into Cs0.32WO3@g-C3N4/PVDF fiber membranes. Water evaporation, desalination, and sewage treatment were studied using the photothermal fiber membranes. The experimental results showed that the highest photothermal conversion could be achieved for a fiber membrane composed of 10\xa0wt% of Cs0.32WO3@g-C3N4. The highest temperature elevations measured were 85\xa0°C and 90\xa0°C under NIR and full solar light, respectively. The membranes exhibited excellent anti-salt fouling behavior while also demonstrating superior water evaporation efficiency and salt rejection 95.4% and 99.9%, respectively. Furthermore, the electrospun fiber membranes showed excellent efficiencies for removing organic dyes, 4-nitro phenol and tetracycline. These superior properties are attributed to the hydrophobicity of PVDF, which enables an air gap to form between the water and the fiber membrane. This air gap selectively admits water vapor into the fiber membrane while salt and organic pollutants diffuse back to bulk water, which is critical for the successful of desalination. This study opens the door to design new multi-functional fiber membranes for sewage treatment, especially for desalination.