Plastic production reached over 400 million metric tons (MMTs) in 2024, but the recycling rate remained less than 10%. In addition to the production of micro- (1 µm to 5 mm) and nano- (1 nm – 1000 nm) sized plastics, the bigger plastics break down due to human and natural factors, which gives rise to smaller plastics. Nano Plastics (NPLs) are an emerging pollutant of concern in this decade. They have several known health effects, including inflammation, oxidative stress, neurological issues, and reproductive issues, in overall plastic pollution. NPLs are found in different water resources; therefore, remediation methods are urgently needed. Metal Organic Frameworks (MOFs) are well-known adsorptive materials for capturing a diverse range of pollutants, including NPs. In this study, a 2D ZIF-L MOF was synthesized in free solution for 48 h and characterized using SEM, XRD, FTIR, BET, and Zeta Potential Measurements. Model PSNPLs was synthesized in the lab employing emulsion polymerization with a controlled size of ~170 nm and characterized with SEM, FTIR, and DLS measurements. The synthesized concentration of the PSNPLs was quantified using UV-VIS spectroscopy. Isotherm adsorption of PSNPLs (100 ppm) with ZIF-L (100 ppm) in free-solution showed ~96% adsorption in 24 h. Kinetic studies revealed ~82% PSNPLS adsorption within 6 h. The adsorption results were attributed to both electrostatic interactions and π-π interactions between ZIF-L and PSNPLs. Membrane-based technology offers several advantages, such as large-volume wastewater treatment and low energy consumption, over other separation methods. However, UF membranes are not entirely effective in removing NPLs due to their size and other physicochemical properties. Adsorptive membranes offer additional benefits by concentrating pollutants directly on the membrane rather than in the retentate. Owing to the superior adsorptive performance, the ZIF-L MOF was in-situ grown on a polydopamine (PDA)-coated UF membrane at different timescales (30 min to 48 h). PDA acted as a bridging agent between the ZIF-L and Polyethersulfone (PES) UF Membrane by leveraging the co-ordinate covalent bonding between the polar groups of PDA and Zn of ZIF-L. 48 h timescale was ideal for in-situ growth of ZIF-L on the PES UF membrane in obtaining a 20 µm thick and compact ZIF-L layer. A 100 ppm PSNPLs solution was filtered using the ZIF-L 48 h functionalized membranes for 12 h in both dead-end and crossflow systems. 48 h ZIF-L functionalized membranes showed >99% removal of PSNPLs compared to the Blank and PDA-modified UF membrane (90%). Mass balance analysis in crossflow filtration revealed ~80% of the separation was due to adsorption in the ZIF-L functionalized membrane, compared to ~13% and 20% in the Blank and PDA-coated membranes, respectively. ZIF-L was regenerated using 0.02 N NaOH in free solution and maintained ~85% adsorption efficiency up to 4 filtration cycles. Xylene was effective in regenerating the ZIF-L functionalized membranes within 5 minutes and showed >97% removal efficiency after 3 cycles.
