Iron- and Zirconium-Modified Nanocellulose Adsorbent: Broad-Range Selectivity Test for Potentially Toxic Elements and Effective Arsenite Removal

Abstract

Iron oxide and its composite adsorbents are widely used for removing arsenic and other potentially toxic elements (PTEs) due to their affordability and eco-friendly properties. However, understanding their selectivity and storage stability is vital for their effective use in practical applications. Current work reports the selectivity behavior of a newly developed adsorbent, iron- and zirconium oxide nanoneedle-impregnated cellulose nanofibers (Fe-Zr-NN-CNF), toward cationic and anionic PTEs. Key findings are- (i) The adsorbent demonstrated exceptional selectivity for anionic potentially toxic elements (PTEs), achieving a removal efficiency of at least 98% across a broad pH range (2–9), while exhibiting minimal selectivity for cationic PTEs; (ii) The adsorbent effectively removed arsenite (As^III) from aqueous media at a dosage of 1 g L^–1 and pH 7.0. High phosphate concentrations hindered As^III removal, whereas chloride, nitrate, and sulfate had negligible effects; (iii) Adsorption kinetics, isotherm studies, Fourier-transform infrared spectroscopy (FTIR), and X-ray absorption spectroscopy (XAS) analyses confirmed that As^III adsorption follows a chemisorption mechanism, involving monolayer binding on a heterogeneous surface; and (iv) The adsorbent exhibited excellent storage stability for at least four weeks at both room temperature (25 °C) and 40 °C, indicating long-term usability in practical applications. Thus, the results suggest that Fe-Zr-NN-CNF could be a potential solution for water remediation strategies.