Improved electrochemical sensor using functionalized silica nanoparticles (SiO2-APTES) for high selectivity detection of lead ions

Abstract

Mesoporous silica nanoparticles, functionalized by APTES, were used to modify glassy carbon electrodes (GCE) and their performance was assessed for the accurate quantification of trace Pb2+ ions under electrochemical methods. Mesoporous (3-aminopropyl) triethoxysilane modified-silica particles (SiO2-APTES), of about 200 nm, were synthesized by the modified Stӧber method in presence of cetyltrimethylammonium bromide. Silica particles were characterized by X-Ray diffraction analysis, scanning electron microscopy, infrared spectrum analysis, and electrochemical techniques such as cyclic voltammetry and electrochemical impedance spectroscopy (EIS). Furthermore, their mesoporous characteristics were investigated by the analysis of N2 adsorption/desorption isotherms. The functional groups on the silica particle surface showed remarkable selectivity towards Pb2+. Various experimental parameters, including incubation time, pH of the buffered solution, and quantity of SiO2-APTES deposited on the electrode were systematically investigated to identify optimal operating conditions for the system. After optimization, the sensors covered a working dynamic range from 8.8 × 10−8 M to 1.2 × 10−6 M achieving a noteworthy limit of detection of 2.6 × 10−8 M. Interference studies have demonstrated that GCE/SiO2-APTES electrodes exhibit high sensitivity and specificity for Pb2+ detection, making them a promising tool for rapid and portable detection of this heavy metal. Finally, the feasibility of these electrodes for Pb2+ ions detection was evaluated in real samples such as seawater (obtained from Monastir, Tunisia) and tap water by using the standard addition method. The high accuracy and reliability of the SiO2-APTES modified GCE was demonstrated by the excellent recovery studies, which ranged from 88 to 104% for all spiked samples. The overall finding supports the practical applicability of this sensor for a real-world context and confirms its potential for environmental monitoring.