High efficiency adsorption of diverse emerging contaminants on MIL-101(Fe): Performance, influencing factors, and mechanistic insights

Emerging Contaminants (ECs) in water bodies pose significant environmental concerns. Adsorption technology, known for its low cost, high efficiency, and ease of use, is a promising solution for ECs removal. This study investigated the adsorption performance of MIL-101(Fe), an iron-based metal-organic framework (MOF), for ECs with different molecular sizes. Sodium p-perfluorous nonenoxybenzenesulfonate (OBS), diclofenac sodium (DCF), and tetracycline hydrochloride (TCH) were selected as representative ECs, covering PFAS substitutes, NSAIDs, and antibiotics. MIL-101(Fe) exhibited specific surface area, excellent mesoporous structure and abundant surface active sites, enabling efficient adsorption. Under optimized conditions (pH = 5.8, 6, and adsorbent dosages 9, 40, 20, and 20 mg), removal efficiencies for OBS, DCF, and TCH reached 95.9 %, 97.5 %, and 86.4 %, respectively. Cyclic tests showed stable performance after five adsorption-desorption cycles. Kinetic studies indicated that OBS followed a pseudo-first-order model, while DCF and TCH adhered to a pseudo-second-order model. The maximum adsorption capacities for OBS, DCF, and TCH were 945.1, 1595.9, and 439.5 mg·g −1 , respectively. Adsorption mechanisms revealed that smaller molecules like OBS and DCF easily entered the mesopores, while larger TCH molecules faced diffusion restrictions. The molecular interactions among OBS, DCF, and TCH involved electrostatic attraction toward -SO₃ − groups and pore filling in OBS, diffusion into the pore interior followed by hydrogen bonding with -NH₂ and π-π stacking in DCF, and surface-confined hydrogen bonding with -OH/-NH₂ and π-π interactions in TCH. This study provided a theoretical basis for efficient treatment of ECs with various molecule structures by Fe-MOFs adsorption materials.