Postsynthetically\nModified Cationic, Robust MOF Featuring\nSelective Separation of Carboxylate-Containing Pharmaceutical Drugs\nfrom Water at Neutral pH: Elucidation of the Adsorption Mechanism\nby Theory and Experiments

The escalating levels of hazardous\npharmaceutical contaminants,\nspecifically nonsteroidal anti-inflammatory drugs (NSAIDs), in groundwater\nreservoir surfaces and surface waterway systems have prompted substantial\nscientific interest regarding their potential deleterious effects\non both aquatic ecosystems and human health. Extraction of those pollutants\nfrom wastewater is quite challenging. Hence, the development of economic,\nsustainable, and scalable techniques for capturing and removing those\npollutants is crucial to ensure water safety. Herein, we demonstrate\na physicochemically stable, reusable, porous Hf(IV)-based cationic\nmetal–organic framework (MOF), namely, <b>1’@MeCl</b> for the aqueous phase adsorption-based removal of NSAIDs (diclofenac,\nnaproxen, ibuprofen) from the wastewater environment. The highly positively\ncharged surface of the <b>1’@MeCl</b> MOF enables it\nto selectively extract more than 99% of diclofenac, naproxen, and\nibuprofen contaminants within less than 30 s. With fast adsorption\nkinetics, very high adsorption capacities (<i>Q</i><sub>e</sub>) were achieved at neutral pH for diclofenac (482.9 mg/g),\nnaproxen (295.9 mg/g), and ibuprofen (219.5 mg/g). Moreover, the influence\nof changes in pH and coexisting anions on the adsorption property\nof the <b>1’@MeCl</b> MOF was studied. Furthermore, the\nadsorption efficiency of <b>1’@MeCl</b> in different\nreal water environments was ensured by performing diclofenac, naproxen,\nand ibuprofen adsorption from tap, river, and lake water. Moreover,\na <b>1’@MeCl</b>-anchored cellulose acetate-chitosan\nmembrane was developed successfully to demonstrate the membrane-based\nextraction of diclofenac, naproxen, and ibuprofen from contaminated\nwater. Furthermore, a molecular-level mechanistic study was performed\nthrough experimental and computational study to propose the plausible\nadsorption mechanisms for diclofenac, naproxen, and ibuprofen over\nthe surface of <b>1’@MeCl</b>.