These article summaries the results of studying the sorption equilibrium of ions close to their concentration in the liquid industrial waste. For experimental research, solutions with concentration of Со²⁺ and Cd²⁺ ions in the range of 1·10^-3–1·10^-4 N have been used. These concentrations match to ion con­cen­tration in industrial liquid waste with the ions mentioned. In the experiments, the Na⁺- modified forms of natural sorbents based on clinoptilolite from the Aydag deposit and on bentonite from the Dash-Salakhli (Azerbaijan) deposit were used. For comparison, among industrial sorbents, we used synthetic cation exchanger KU–2–8 (styrene and divinylbenzene co–poly­mer), which we modified in H⁺, Na⁺-form. The thermodynamic constant of ion-exchange equilibrium for differently charged ions, calculated by the Gorshkov-Tolmachev formula, does not depend on the solution concentration, and to calculate this value, it is not required to determine the activity coefficient. Based on experiments to determine equilibrium concentrations, we can recommend inexpensive and available Na-clinoptilolite and Na-bentonite instead of synthetic industrial KU-2-8 for the sorption extraction of Co²⁺ and Cd²⁺ ions from wastewater

doi.org/10.32737/0005-2531-2022-4-122-127