Enhanced flux of nanofiltration membranes for low molecular weight solutes using Zr-MOF@MoS2 nanohybrids as both interlayer and filler materials

This study investigates the fabrication and performance of polyamide (PA) thin film composite (TFC) membranes for nanofiltration applications, incorporating nanosized (∼10 nm) zirconium-based metal-organic frameworks (MOFs) and MoS₂. Three different Zr-MOFs, namely UiO-66, UiO-66-NH₂ and MOF-808, were synthesized and anchored onto 2D MoS₂ nanosheets forming MOF@MoS₂ nanohybrids. These nanohybrids were integrated into PA TFC membranes using two distinct methods: (i) embedding them into the PA layer, resulting in thin film nanocomposite (TFN) membranes, and (ii) creating bilayered membranes with the nanohybrids beneath the PA layer. The membranes were evaluated for the removal of organic dyes, such as Rose Bengal (RB, 1017 Da), Sunset Yellow (SY, 452 Da) and Acridine Orange (AO, 265 Da), from water. The TFN membranes containing UiO-66@MoS₂ nanohybrids exhibited the highest performance, with a water permeance of 12 L·m⁻²·h⁻¹·bar⁻¹ for the SY dye solution, representing a 140 % increase relative to the control PA TFC membrane. All membranes exhibited high rejection values (> 98 %), with performance strongly influenced by the dye size and charge. The characterization revealed that the porosity and sorption capacities of the nanohybrids are crucial to obtain more permeable membranes, but other factors such as negative surface charge, roughness and hydrophilicity play an important role.