DETERMINATION OF THE MECHANISM OF INTERACTION OF Cu2 +, Pb2 + METHOD OF FTIR SPECTROSCOPY IN THE MIDDLE REGION

The object of the study is to determine the interaction of copper and lead ions in aqueous weakly acidic solutions. According to the analysis of modern scientific works, recently not enough attention is paid to the study of sorption properties of humates after regeneration, so for further use of humic acids as sorbents, including regenerated, it is important to obtain data on stoichiometric interaction of humic acids with various metals. In this work, humic acids were isolated from commercial potassium humate produced in China. Model solutions of copper (II) sulfate and lead (II) acetate were used in the research. The exact content of copper and lead for the final solutions prepared from model with subsequent regeneration of humate-metal complexes was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Regeneration was carried out by reducing the acidity by adding 1 n nitric acid. The spectra were recorded by FTIR spectroscopy in the middle region. Interpretation of the spectra of the starting humic acids, potassium humates, as well as copper and lead humates was carried out by adjusting the literature data. 
Studies of the structure of humic acids and humates of metals and by this method have shown the active involvement of carboxyl groups in the formation of humate-metal bonds. Humic acids after regeneration (reduction) contain carboxyl groups in the dimerized state, in contrast to freshly prepared humic acids. In lead humates, the above general nature of changes in the spectral pattern from humic acids to lead humates is repeated for copper humates, which can be explained in the general theory of FTIR spectroscopy by increasing the reduced mass of a group of atoms involved in oscillations due to significantly higher atomic mass of pigs. compared to copper. 
It was also found that sorption occurs as a result of stoichiometric reaction, due to which chelate complexes of copper and lead are formed by interaction with oxygen atoms in the carboxyl groups of humate molecules.