An Electrochemical Sensor for Detection of Lead (II) Ions Using Biochar of Spent Coffee Grounds Modified by TiO2 Nanoparticles

Toxic heavy metal ions, such as lead ions, significantly threaten human health and the environment. This work introduces a novel method for the simple and sensitive detection of lead ions based on biochar-loaded titanium dioxide nanoparticles (BC@TiO₂NPs) nanocomposites. Eco-friendly biochar samples were prepared from spent coffee grounds (500 °C, 1 h) that were chemically activated with TiO₂ nanoparticles (150 °C, 24 h) to improve their conductivity. Structural characterizations showed that BC@TiO₂NPs have a porous structure. The BC@TiO₂NPs material was evaluated for lead ion determination by assembling glassy carbon electrodes. Under optimal conditions, the sensor was immersed in a solution containing the analyte (0.1 M NaAc-HAc buffer, pH = 4.5) for the detection of lead ions via differential pulse voltammetry. A linear dynamic range from 1 pM to 10 μMwas achieved, with a detection limit of 0.6268 pM. Additionally, the analyte was determined in tap water samples, and a satisfactory recovery rate was achieved.