Composite coatings of poly(methyl methacrylate) with silicon dioxide nanoparticles for capacitive sensors of nickel content control in water

Pollution of the environment, in particular water sources, with heavy metals is a serious environmental problem. In this regard, it is relevant to develop new sensor systems that allow rapid tests and are not inferior in analytical parameters to classical methods for detecting heavy metals. Promising materials for creating such sensor systems are composite coatings based on polymer compounds with inorganic nanoparticles. The article presents the results of using poly(methyl methacrylate) (PMMA) coatings and PMMA nanocomposites with silicon dioxide nanoparticles (SiO2 NPs) to develop capacitive sensors for analyzing the content of Ni2+ ions in water. The structural and morphological characteristics of a conductive nickel layer and nanostructured films based on poly(methyl methacrylate) were studied using atomic force microscopy. Based on the experimental data on the dependence of the capacitance characteristics of sensors on the concentration of Ni2+ in solutions, the operating characteristics of sensors were established: response time is 5 min; working range of concentrations of Ni2+ ions: 1 ‧ 10–3 – 50 mM; lower detection limit ≈ 0.06 mg/l (maximum nickel concentration limit in water is 0.1 mg/l). It has been shown that the formation of a coating of the composition PMMA + NPs-SiO2 (1 : 41.7 mol) on a conductive nickel layer using the spin-coating method leads to increasing the sensitivity of a sensor and its service life (up to seven cycles).