MIL-100-Fe self-assembled cellulose nanofibers sponge for Diclofenac cascade encapsulation

The conventional hydrothermal synthesis and inherent hysteresis behavior limited the application of MOFs owing to the low kinetic efficiency in dynamic molecular adsorption. Herein, we developed an in-situ nucleation strategy for the preparation of MIL-100-Fe and immobilized it with hierarchy porous scaffold of TEMPO oxidized cellulose nanofiber (TCNF) sponge in the absence of additional organic solvent during fabrication under ambient conditions. The newly recognized mechanisms of gradient molecular transfer were proposed to illustrate the comprehensive DCF adsorption process from solution to micropores of MIL-100-Fe at molecule level triggered by the stray capacitance, varied Laplace pressure, size exclusion and cellulosic labyrinth. Additionally, the superior biocompatibility and natural degradability (in 24 h) of MIL@TCNF sponge were demonstrated. The used material could be converted rapidly to zero-valent iron (ZVI) sponge via simple reduction process, achieving both dehalogenation of Diclofenac (DCF) and material regeneration. These findings uncover the propagable mechanisms of molecular-diffusion driven adsorption cascade and provide a novel fabrication strategy of 3-D environmental functional sponge with reusability and biodegradability for water pollution control.