Novel multifunctional RbxWO3@Fe3O4 immobilized Janus membranes for desalination and synergic-photocatalytic water purification

In this work, novel multi-functional Janus membrane was developed by incorporating solar active RbxWO3@Fe3O4 nanocomposites into recycled triacetate cellulose (rTAC) that used as host matrix and PET as substrate by solution electrospinning. The Janus membrane was purposely designed with a porous and hydrophobic rTAC top layer containing functional composite and hydrophilic and nonwoven PET bottom layer to have opposite surface wettability to ease water pumping from PET nonwoven. RbxWO3@Fe3O4 nanocomposite was selected for its excellent full-spectrum solar light absorption. The multi-function applicability of the developed Janus membrane was systematically investigated for interfacial water evaporation, photothermal conversion, sewage treatment, desalination as well as simultaneous photocatalysis and water evaporation. The result revealed that the developed Janus membrane exhibited outstanding water evaporation, photothermal conversion, desalination, sewage treatment, and photocatalytic properties. In particular, Janus membranes comprising 10 wt% RbxWO3@Fe3O4 nanocomposite at 1:2 M ratio displayed 89% water evaporation efficiency, almost 99.9% ions rejection for organic pollutants, excellent desalination by evaporation, and synergic photocatalysis for bulk water as well as clean water production at the same time. This is the first reported study producing clean water from wastewater by simultaneous water evaporation and photocatalytic conversion of harmful pollutant in the bulk water to harmless one at the same time in addition to the sewage treatment, photothermal conversion and desalination properties including sewage treatment, photothermal conversion, and desalination. Thus, the fabricated Janus membrane offers a promising candidate for wastewater.