Phytic acid-functionalized Zr-MOF mixed matrix membranes with UF-level water permeance, NF-level separation efficiency, and antifouling properties for the removal of dyes and heavy metals

Although there have been substantial investments and a prevalent focus on developing hydrophilic membranes with fine-tuned pore sizes, they have proven ineffective in rejecting persistent contamination from dyes and heavy metals in water. Some research has been conducted on phytic acid and its metal complex-coated membranes, but challenges regarding layered aggregation of these complexes remain unsolved. To address this, we prepared hydrophilic mixed matrix membranes (MMMs) by incorporating phytic acid-functionalized NH₂UiO-66 (PNU) nanoparticles into a polysulfone (PSF) membrane matrix. Prior to MMM studies, batch adsorption confirmed the relevance of post-modification, with PNU fillers showing 7%p and 5%p higher removal efficiency than NH₂UiO-66 (NU) for Pb²⁺ and MB, respectively, and maximum adsorption capacities of ~185 and ~295 mg g⁻¹ for PNU, compared to ~90 and ~184 mg g⁻¹ for NU. For membranes, the presence of polar functional groups including –COOH, –NH₂, and abundant additional phosphate (–PO₄) groups creates a hydration layer that significantly enhances the water permeance of PSF/PNU membranes compared to pristine PSF and PSF/NU-0.5. The optimized PSF/PNU-1 exhibited the highest initial water permeance (69.2 LMH/bar) comparable to the ultrafiltration level, whereas removal efficiencies at the nanofiltration level were observed for PSF/PNU-1 and PSF/PNU-2 (98.5% and 99% for MB and 95% and 86% for Pb²⁺, respectively). Moreover, PSF/PNU-1 showed noticeable hydrophilicity, reasonable surface roughness, and an FRR over 88%, proving phytic acid-modified NH₂UiO-66 to be a remarkable filler for MMMs with effective antifouling properties. We expect that this work will offer valuable insights into a breakthrough membrane modification process that is rapid, scalable, and cost-effective for adsorptive MMMs in wastewater treatment, through a dual-level analysis linking the fundamental structure–property relationships of MOFs to membrane behaviors.