Efficient mercury ion abatement through highly porous cellulose nanofibrils combined with microporous organic polymer enhancements

Abstract

Pristine microporous organic polymer (p-MOP), owing to the presence of heteroatoms, has emerged as a significant platform for sensing and adsorption of heavy metal ions. The present work is a novel approach for developing highly porous hybrid architectures with trimesic acid and phenylene diamine-based p-MOP embedded over rice straw-derived cellulose nanofibers (ACNFs/MOP) for the sensing and remediation of mercury ions in the aqueous medium. The ACNFs/MOP were successfully characterized by various techniques, such as FTIR spectroscopy, BET surface area analysis, X-ray diffraction, XPS, HR-TEM, and TGA. The hybrid exhibited excellent porosity and crystallinity. The ACNFs/MOP hybrid was highly selective for Hg(II) ions, displaying substantial enhancement in fluorescence intensity with an LOD of 3.927 nM while also facilitating simultaneous adsorption. The adsorption showed a strong fit with pseudo-second-order kinetics and Langmuir isotherm models with an excellent adsorption capacity of 416.18 mg g−1, attributed to electrostatic interactions, coordination surface complexation, and metal-π interactions, as confirmed by XPS studies. Thermodynamic studies indicated an endothermic adsorption process. Box-Behnken Design-Response Surface methodology with Design Expert Software-13 was applied to model the process parameters. The hybrids were 97 % efficient even after five cycles of reusability, exhibiting their excellent potential for removing perilous Hg(II) ions from wastewater.