Multidimensional Nickel-Based Nanoporous Metal–Organic Framework-Integrated Photoactive Membranes for Pollutant Separation and Degradation in Wastewater Treatment

This study investigates the influence of dimensionality and ligand chemistry on the photocatalytic and membrane performance of nickel-based nanoporous metal–organic frameworks (Ni-MOFs) for wastewater treatment. Ni-MOFs with distinct morphologies, 1D rods, 2D sheets, and 3D particles, were synthesized via a solvothermal method using terephthalic acid (NTA) and 2-aminoterephthalic acid (NATA) as ligands. Structural analysis by XRD and FESEM confirmed nanocrystalline frameworks with morphology-dependent variations. Optical and electrochemical studies revealed ligand- and dimension-induced changes in electronic structure, including tunable band gaps and improved charge separation, which directly influenced photocatalytic activity. Under solar irradiation, 2D-NATA showed the highest photocatalytic efficiency, degrading ∼94% of rhodamine B (RhB) and ∼62% of Congo red (CR), followed by 3D-NATA with ∼72 and ∼65% degradation, respectively. Incorporation of Ni-MOFs into polysulfone (PSF) membranes at 5 wt % loading enhanced membrane performance. The 2D- and 3D-NATA systems exhibited superior dye rejection (∼62 and ∼92% for RhB; ∼94 and ∼86% for CR) and increased water flux (∼72.3 and 59.4 L/m2·h for RhB; ∼34.1 and 50.2 L/m2·h for CR). In addition, the 2D-NATA membrane demonstrated self-cleaning ability, achieving ∼18.3% RhB and ∼16.7% CR photodegradation of adsorbed dyes under sunlight. These results highlight the pivotal role of MOF dimensionality and ligand design in enhancing both photocatalytic and membrane functionalities, positioning Ni-MOF-based membranes as promising candidates for efficient and sustainable wastewater treatment.