Sustainable nanocellulose recovery from newspaper waste to fabricate a composite for sensing and scavenging copper and iron in aqueous effluents and mining wastes

This study offers a straightforward and economical method for recovering cellulose nanoparticles (CNMs) from post-consumer newspaper trash in a sustainable manner. The recovered CNMs were subsequently utilized to fabricate a novel solid-state visual composite by immobilizing a newly synthesized fluorescent Schiff base ligand, (saldach(Et₃N⁺PF₆⁻)₂, H₂L) (Saldach ligand). Both the quick and on-site visual identification of Cu²⁺ and Fe³⁺ ions in aqueous solutions and the effective elimination of these heavy metal pollutants from mining effluent were proved by the resultant Saldach-composite. The Schiff base ligand, characterized by FTIR, NMR, and ESI-MS, exhibited selective binding toward Cu²⁺ and Fe³⁺ ions, leading to quantifiable UV–Vis spectroscopy. The morphology and composition of the CNMs and the Saldach-composite were investigated using SEM, TEM, DLS, XRD, and XPS analysis, confirming the successful incorporation of the Schiff base onto the CNM matrix. Additionally, the binding mechanism between the Saldach-composite and the target metal ions was clarified by the use of density functional theory (DFT) calculations. For the simultaneous detection and removal of Cu²⁺ and Fe³⁺ from mine waste, the developed solid-state visual composite presents a viable, economical, and ecologically friendly alternative, especially addressing the difficulties related to mining waste management.