Zwitterionic and Photocatalytic Janus Membrane Based on Diethylamine N-Oxide Group and WS2 Nanosheets for Dye Removal in Forward Osmosis

The search for innovative materials with unique properties to aid in the remediation of polluted water effluents is increasingly imperative. Herein, we present the fabrication of a Janus membrane operated in forward osmosis mode that combines the advantages of polymeric and semiconducting materials. This membrane was prepared postmodifying a polysulfone backbone with the zwitterionic group amine N-oxide (DEAO). Then, a thin layer of WS2 nanosheets was deposited over the membrane to incorporate a photosensitive layer. The fabricated membranes were thoroughly characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), surface Z-potential, and water contact angle (CA). The performance of the prepared membranes was assessed in terms of the water permeance and their ability to degrade a model dye (rhodamine B (RhB)). The results suggest the photodegradation of the RhB above 92% and 98% after 8 and 12 h, respectively. These degradation performances are almost 20% higher than the control membranes, and reactive oxygen species (ROS) are likely formed by the WS2 nanosheets, which accelerates the degradation process. These results are encouraging, as this technology may open the door to fabricating membranes with dual functions.