A Bifunctional Cellulose/MIL-53(Fe) Paper-Based Material for Selective Fluorescent Sensing of Cr(VI) and Wastewater...

The pervasive toxicity of hexavalent chromium (Cr(VI)) to aquatic life and humans urgently demands integrated platforms capable of simultaneous detection and remediation. Herein, a bifunctional platform (CMC/PEI/MIL-53(Fe)/Nap/CP) capable of simultaneous fluorescence detection and photocatalytic removal of Cr(VI) was constructed by in situ growing MIL-53(Fe) on a carboxymethyl cellulose/polyethylenimine (CMC/PEI) matrix grafted with naphthalimide and combining it with cellulose paper (CP). In situ growth ensures the uniform dispersion of active sites, while the paper-based design enhances processability and recyclability. The protonated amino groups of PEI enrich Cr(VI) through electrostatic interactions, while MIL-53(Fe) provides photocatalytic active sites through the Fe³⁺/Fe²⁺ redox cycle. Due to the synergistic effect of adsorption and photocatalysis, the removal efficiency reached 99% within 5 h, with a reduction rate of 96%, following pseudo-first-order kinetics (k = 0.9119 h^-1). Compared to other recent studies, it offers an excellent removal performance. At the same time, the enrichment effect of PEI enhanced the interaction between Cr(VI) and the naphthalimide fluorophore, achieving a detection limit of 0.34 μM and a K_SV of 8.73 × 10³ M^-1. The good selectivity for Cr(VI) was theoretically verified through simulations by using Materials Studio software (MS). This platform provides a practical bifunctional platform for efficient fluorescence detection and removal of Cr(VI), with broad application prospects in the fields of environmental monitoring and water treatment.