Enhancing nanofiltration performance with tannic acid and polyvinyl alcohol interlayers for improved water permeability and selective solute rejection

Abstract

Global water shortages have significantly intensified the demand for efficient and sustainable water purification technologies. Nanofiltration (NF) plays a crucial role in desalination, providing distinct advantages by removing a variety of pollutants including heavy metals and organic compounds, all while consuming minimal energy. Traditional NF membranes often struggle to balance high rejection with satisfactory permeability. This study advances NF technology by utilizing polysulfone as a durable substrate and introducing tannic acid (TA)-polyvinyl alcohol (PVA) interlayer to enhance structural robustness and functional capabilities of membranes. Through streamlined one-step coating followed by precise interfacial polymerization, this approach optimizes monomer piperazine storage and dispersion on substrate, effectively controlling its diffusion rate, resulting in a thinner polyamide (PA) layer. These strategic enhancements not only lead to a significant increase in permeability to 216.3 L·m⁻²·h⁻¹·MPa⁻¹ and an impressive rejection for Na₂SO₄ of 99.04 % but also ensure enhanced long-term operational stability. The innovative TA-PVA interlayer sets new benchmarks for high-performance NF membranes by combining environmental friendliness with cost-effectiveness, making it ideal for large-scale industrial applications. This unique composition promotes sustainability and economic efficiency in water treatment technologies, and underscoring the vast potential for expanding the production and application of advanced NF systems.