Ferrocene anchored fluorescent cellulose nanofibers for ultrasensitive detection, adsorption, and Fenton degradation of norfloxacin: VOSviewer analysis, performance, mechanism, & RSM optimization

As revealed by in-depth state-of-the-art literature analysis using VOSviewer, no study to date has been specifically reported on the Ferrocene carboxaldehyde anchored on the aminated cellulose nanofibers (FcCA@ACNFs) multifunctional hybrid fluorescent sensor, especially for comprehensive wastewater remediation encompassing trace-level detection, efficient adsorption, and Fenton-based degradation of Norfloxacin (NOR) antibiotic from wastewater. Hence, this study has addressed this aforementioned shortcoming by critically synthesizing and comprehensively characterizing a novel fluorescent sensor, FcCA@ACNFs, formed via covalent Schiff base bonding between the Ferrocene carboxaldehyde (FcCA) and aminated cellulose nanofibers (ACNFs). The fluorescence was significantly enhanced in the presence of NOR, exhibiting a high turn-on selectivity with LOD of 0.97 nM in the linear range of 1-100 mg L-1. The average fluorescence lifetime, ⟨τ⟩, estimated using time-resolved fluorescence lifetime spectroscopy, was 3.4905 ns for a higher concentration of NOR in the FcCA@ACNFs-NOR complex, indicating a near-high analyte concentration. Additionally, the statistical tool, Response Surface Methodology (RSM) using Box-Behnken Design (BBD) was used to determine the effect of pH, time, NOR concentration, and FcCA@ACNFs dosage on % adsorption. Adsorption kinetics were described using a pseudo-second-order kinetic model, yielding a maximum Langmuir adsorption capacity of 416.66 mg g-1 and R2 of 0.9992. Concomitantly, FcCA@ACNFs completely degraded NOR in the presence of co-oxidant H2O2, as evident from LCMS studies. Fenton-based degradation followed first-order kinetics had a rate constant of 0.1767 min-1 and a t1/2 of 3.92 min. Under the optimized conditions, 69.87% mineralization of NOR was achieved within 60 min, as confirmed by TOC analysis, indicating substantial mineralization of NOR and its degradation intermediates. FcCA@ACNFs exhibited an excellent removal rate of 94.6% even after 10 cycles. Finally, the efficacy of multifunctional FcCA@ACNFs was established for real water-sample analysis, validating their potential as a promising material for ultra-sensitive detection and comprehensive removal of NOR from wastewater.