Improvement of Permeability and Antifouling Properties of Polyamide Thin-Film Nanocomposite Nanofiltration Membranes Using Boron Nitride Quantum Dots

Nanofiltration membranes play a crucial role in various separation processes, demanding continuous advancements to improve their performance and address challenges such as fouling. In this study, we present the fabrication and characterization of a high-flux thin-film composite nanofiltration membrane (TFC NF) through the incorporation of hydrophilic boron nitride quantum dots (BNQDs) at various concentrations (0.001-0.02 wt %). The membranes were synthesized by using interfacial polymerization between piperazine and trimesoyl chloride monomers. Surface analyses, including contact angle measurements, field emission-scanning electron microscopy, and atomic force microscopy, revealed that the membranes with incorporated BNQDs exhibited a smoother, more uniform, thinner, and more hydrophilic surface. Zeta potential measurements confirmed an increase in the negative surface charge of the NF membranes containing BNQDs. The separation efficiency was evaluated through a cross-flow filtration setup, with the TFC NF membrane containing 0.01 wt % BNQDs demonstrating the highest separation efficiency: 96.56% for Na2SO4, 96.48% for MgSO4, 91.3% for MgCl2, and 51.38% for NaCl, coupled with a water flux of 150.5 L/m(2) h. Furthermore, water flux was enhanced in all modified membranes, reaching a maximum of 170% of the bare membrane flux (195.5 L/m(2) h) in the TFC NF membrane containing 0.02 wt % BNQDs. However, with the increased flux in the TFC NF 0.02 wt % membrane, rejection rates for Na2SO4 and NaCl decreased by 1.84 and 7.15%, respectively, compared to the TFC NF 0.01 wt % membrane. Antifouling properties were evaluated by filtration of a bovine serum albumin /NaCl solution, with all modified membranes exhibiting improved antifouling properties. The TFC NF 0.02 wt % membrane demonstrated superior antifouling performance.