Highly Effective Removal of Nonsteroidal Anti-inflammatory Pharmaceuticals from Water by Zr(IV)-Based Metal–Organic Framework: Adsorption Performance and Mechanisms

Nonsteroidal anti-inflammatory pharmaceuticals are emerging organic micropollutants in surface water, groundwater, and wastewater, whose removal is very important yet challenging. As a new class of porous functional materials, metal–organic frameworks (MOFs) have attracted extensive attention for their adsorption applications. Here, we report that Zr­(IV)-based MOFs (defective UiO-66, and MOF-808) have extraordinary adsorption ability to remove nonsteroidal anti-inflammatory pharmaceuticals from water. Excellent adsorption performances are obtained for UiO-66 and MOF-808, particularly for UiO-66, of which the adsorption capacities are the highest in a wide series of adsorptive materials previously reported. It is elucidated that the incomplete-coordinated cationic Zr in the cluster has high affinity for the anionic pharmaceutical (chemical adsorption) and that the adsorption interaction between the benzene ring of the pharmaceutical and MOF’s ligand is involved to enhance or as an alternative to the adsorption interactions (π–π interaction). In particular, adsorption of ibuprofen, ketoprofen, naproxen, indomethacin, and furosemide by UiO-66 and MOF-808 and the synergetic effect of chemical adsorption and π–π interaction are outstanding, leading to extremely higher binding energies (Ebind) and sorption abilities.

非甾体抗炎药物（Nonsteroidal anti-inflammatory pharmaceuticals）是广泛分布于地表水、地下水与废水中的新兴有机微污染物，其去除兼具重要性与挑战性。作为一类新型多孔功能材料，金属有机框架（metal–organic frameworks, MOFs）因其吸附应用潜力受到广泛关注。本研究报道，基于四价锆（Zr(IV)）的金属有机框架（缺陷型UiO-66与MOF-808）具备优异的吸附性能，可用于去除水中的非甾体抗炎药物。UiO-66与MOF-808均展现出优异的吸附性能，其中UiO-66的吸附容量在既往报道的大量吸附材料中处于顶尖水平。研究阐明，框架团簇中配位不饱和的阳离子锆位点与阴离子型药物分子具有高亲和性，此为化学吸附过程；同时药物分子的苯环与金属有机框架配体之间存在吸附相互作用，可强化吸附效果或作为化学吸附的补充作用机制（即π–π相互作用）。尤为突出的是，UiO-66与MOF-808对布洛芬（ibuprofen）、酮洛芬（ketoprofen）、萘普生（naproxen）、吲哚美辛（indomethacin）以及呋塞米（furosemide）的吸附效果，以及化学吸附与π–π相互作用的协同效应均极为优异，由此获得了极高的结合能（Ebind）与吸附性能。