Multifunctional Zwitterionic-WS₂ Membranes for Enhanced Dye Removal and Biofouling Resistance in Forward Osmosis

Area of Science:

• Materials Science and Engineering
• Environmental Science and Technology
• Nanotechnology

Background:

• Conventional water treatment methods struggle with emergent contaminants and biofouling.
• Development of advanced materials is crucial for efficient and sustainable water purification.
• Forward osmosis (FO) offers advantages but requires optimized membrane technology.

Purpose of the Study:

• To develop a bioinspired, multifunctional membrane for enhanced pollutant removal and anti-biofouling properties.
• To integrate tungsten disulfide (WS2) nanosheets into a polysulfone (PSF) membrane for improved performance in forward osmosis (FO).
• To investigate the photodegradation and adsorption capabilities of the novel membrane against model dyes and its efficacy against bacterial proliferation.

Main Methods:

• Synthesis of a polysulfone (PSF) membrane modified with diethylamine N-oxide (DEAO) and tungsten disulfide (WS2) nanosheets.
• Characterization using scanning electron microscopy (SEM), surface ζ-potential, and water contact angle (CA) measurements.
• Evaluation of water permeance, dye rejection (rhodamine B and sulforhodamine), photodegradation, adsorption, and antibacterial activity.
• Density functional theory (DFT) computations to understand electronic band edges and adsorption mechanisms.

Main Results:

• The PSF-DEAO@WS2 membrane demonstrated efficient photodegradation (~50% for RhB) and adsorption (>80% for SR101) of model dyes.
• Dye rejection performance was significantly higher (30-75%) compared to control membranes, with nearly 99% rejection of RhB under FO conditions.
• The membrane exhibited excellent water flux and effectively inhibited the proliferation of Escherichia coli, indicating anti-biofouling properties attributed to ROS generation by WS2.

Conclusions:

• The developed bioinspired membrane integrates polymeric and semiconducting properties for superior water treatment.
• Tungsten disulfide (WS2) nanosheets enhance pollutant degradation, adsorption, and provide significant anti-biofouling capabilities.
• This multifunctional membrane design offers a promising pathway for advanced water purification technologies, addressing challenges of emergent contaminants and biofouling.