Research subject: In the present study, Fe₃O₄@SiO₂ nanoparticles functionalized with polymer dendrimer molecules are synthesized by the Stöber method. The synthesized nanostructure is applied as a recognition element in the structure of a carbon paste electrode for monitoring copper ions from aqueous solutions and real samples of the cooling tower of a thermal power plant.  One of the main applications of this sensor is as a key condition monitoring method for measuring copper ions in industrial cooling towers.
Research approach: The surface chemistry, particle size, and morphology of the synthesized nanoparticles are evaluated using transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, vibrating sample magnetometer, thermal weighing analysis, and energy dispersive X-ray spectroscopy. In order to optimize the performance of the copper ion monitoring sensor, parameters such as graphite percentage, paraffin, and detector composition are evaluated.

Main results: The highest sensor response is achieved at 75% graphite, 20% paraffin, and 5% nanostructure percentage. The behavior of copper ions is investigated using cyclic voltammetry, and an oxidation peak is obtained at 0.2 V region for copper oxidation. The obtained sensor has a detection limit of 10^-5 M and a linear range of 0.1-1 mM in differential pulse voltammetry. The proposed sensor is capable of application in real complex samples, such as a power plant cooling tower water. The results of the presented method are in agreement with the atomic absorption reference techniques. The proposed method is able to measure copper ions in a cooling tower sample with high accuracy and precision.