Polydentate Adsorbent of Transition Metals Based on Hyperbranched Polyester Polyphthalate

At present, multifunctional adsorbents capable of not only effectively binding metal ions but also maintaining stability under aggressive conditions (e.g., in an acidic medium) are of great interest. In this work, Cu(II) and Co(II) complexes based on hyperbranched polyester polyphthalate are obtained and characterized for the first time. Complexation is confirmed by IR and electron spectroscopy methods, which revealed the monodentate nature of the coordination of carboxylate groups and the formation of covalent bonds with metals. The coordination units of the complexes have a six-coordinated octahedral geometry with tetragonal distortion, and the ligand:metal molar ratio is 4:1. Calculation of the stability constants showed high stability of the complexes with logarithms of the constants of 18.11 for Cu(II) and 17.23 for Co(II). The TGA method established that the onset temperature of destruction of the copper and cobalt complexes is 210 and 252°C. The ligand demonstrated high sorption capacity for Cu(II) and Co(II) ions—47.88 and 28.21 g/kg, respectively, while desorption was not observed even at low pH (1), which indicates the strength of the complex bonds. These results indicate the possibility of using the macroligand as a sorbent in an acidic environment, for example, in the purification of industrial wastewater and mine waters.