Interface-directed design of glycidyl methacrylate-functionalized UiO-66 for thin film nanofiltration membranes in heavy metals rejection

Thin film nanocomposite (TFN) membranes incorporating metal organic frameworks (MOFs) have attracted considerable interest for heavy metal separation; however, their performance is often limited by poor filler–polymer compatibility and non-selective interfacial defects. In this study, an interface-engineered TFN membrane is developed by incorporating glycidyl methacrylate–functionalized UiO-66-NH₂ (GMA-UiO-66) into a polyamide selective layer formed via interfacial polymerization. GMA functionalization is employed to improve filler integration within the polyamide matrix through enhanced interfacial interactions, rather than to increase intrinsic porosity or surface hydrophilicity. Comprehensive characterization (XRD, FTIR, BET, SEM) confirms that GMA modification preserves UiO-66 crystallinity while inducing modest reductions in accessible surface area and membrane porosity, accompanied by a slight increase in contact angle due to altered surface chemistry. Cross-sectional SEM analysis reveals a well-defined polyamide active layer with improved morphological continuity in GMA-UiO-66-based TFN membranes relative to membranes containing unmodified UiO-66-NH₂. Under dead-end nanofiltration conditions (6 bar, 50 mg L⁻1 model solutions), the optimized GMA-UiO-66 TFN membrane exhibits rejection values of 97% for Pb2⁺ and 93% for arsenate, alongside stable water flux compared with the control polyamide membrane as compared to optimized UiO-66-NH2 TFN membrane & pristine TFC membrane which showed lower rejections (94% for Pb(II) and 92% for As(V)) and (75% for Pb(II) and 70% for As(V)) respectively. These rejection levels are achieved under feed concentrations substantially higher than typical drinking-water levels, highlighting the membrane’s capability to significantly reduce heavy metal loads under challenging conditions. Comparative analysis with recently reported MOF-based TFN and nanofiltration membranes demonstrates that the observed performance is competitive within the context of single-pass nanofiltration pretreatment. This work positions GMA-functionalized UiO-66 as a design platform for interface engineering in TFN membranes, offering insights into how organic monomer modification of MOF fillers influences membrane structure–performance relationships. The findings provide a mechanistic foundation for future studies targeting long-term stability, fouling resistance, and multi-stage treatment integration for practical heavy-metal removal applications.