The paper presents the outcomes of a research of the interplay of heavy steel cations Fe3+, Cr3+, Cu2+, Pb2+, Zn2+, Ni2+, Ag+ with carbon dots synthesized by the hydrothermal methodology in water. It was discovered that every one the studied cations quench the fluorescence of nanoparticles to at least one diploma or one other. The collection of cations have been decided based on the diploma of their affect on the fluorescence of carbon dots. The mechanisms of quenching the fluorescence of carbon dots upon interplay with cations have been investigated. It’s proven that the quenching of the luminescence of nanoparticles within the presence of the investigated cations of heavy metals has a posh character. The noticed modifications within the depth of fluorescence of carbon dots are the results of a superposition of a number of elements—electrostatic interactions of steel cations with floor fluorophores of carbon dots, aggregation of nanoparticles, and the impact of an interior filter for iron ions.