ИСТИНА

The relevance of the development of optical nanosensors of environmental parameters is due to the active development of science and industry, where the problem of controlling the content of substances in multicomponent media is becoming increasingly acute. Оne of the most promising bases for sensors are carbon dots (CD), which have photoluminescence (PL) that is sensitive to environmental parameters. The objects of our study were CD synthesized by hydrothermal method from citric acid and ethylenediamine. The effect of temperature, pH, ions present in the medium, on CD PL was found. In this study, the mechanisms of pH and temperature influence on CD PL were studied by quantum calculations of the behavior of surface groups at various pH and by the results of analysis of dependences of CD ζ-potentials on the pH. Using the artificial neural networks, CD-based nanosensors were developed that allow measuring the temperature and pH of the environment with an accuracy of 0.67°C and 0.005, respectively. As a result of studying the interactions of CD with metals ions, the sensitivity of CD PL to certain ions was discovered and confirmed by molecular dynamics calculations. Using the Stern-Volmer theory and PL decay kinetics, it was found that the main type of PL extinguishing by ions is a dynamic mechanism. The use of convolutional neural networks made it possible to develop a CD nanosensor that provides the accuracy of the simultaneous determination of Cu²⁺, Ni²⁺, Al³⁺, Co²⁺, Cr³⁺, Pb2+ and NO3-in water from 0.21 to 1.00 mM. The obtained errors satisfy the needs of monitoring the composition of waste and process waters. The results were obtained using laser photoluminescence spectroscopy, time-resolved spectroscopy, laser correlation spectroscopy, IR absorption spectroscopy.