Eco‐Friendly Nanocellulose‐Based Fluorometric Sensor for Ultra‐Sensitive Detection and Removal of Mercury Ions From Water
Mohammed T. Alotaibi, Wesam Abd El‐Fattah, Ahmad A. Alluhaybi, Abdu Subaihi, Reda F.M. Elshaarawy, Ahmed Shahat
Abstract
ABSTRACT A novel solid‐state fluorometric sensor based on wastepaper‐derived nanocellulose (NC) functionalized with 4‐hydroxy‐3‐(((2‐mercaptophenyl)imino)methyl)benzyl)triphenylphosphonium hexafluorophosphate (TPPAT) was developed for the ultra‐sensitive detection and simultaneous removal of Hg 2+ ions from water. The NC‐TPPAT composite exhibits a linear detection range of 0–50 μM and a limit of detection (LOD) of 4.11 × 10 −8 M with the fluorescence technique and 3.31 × 10 −8 M with UV–Vis technique. Rapid fluorescence response kinetics achieve signal equilibration within 100 s under optimized conditions (pH 4.5, 25 °C, 30 mg sensor dose). In parallel, batch adsorption studies revealed a Langmuir monolayer capacity of q max = 225.6 mg g −1 and pseudo‐second‐order kinetics (R 2 = 0.996), with equilibrium reached at 60 min (pH 5.3, 25 °C). Selectivity assays demonstrated negligible interference (< 5% signal deviation) from competing metal ions, including Cu 2+ ions. The sensor maintains > 90% performance over five reuse cycles. This integrated NC‐TPPAT platform combines eco‐friendly material design, high sensitivity, and efficient Hg 2+ ions removal, achieving a remarkable removal efficiency of up to 97.42%, offering a practical approach for real‐time environmental monitoring and water purification.