Sorption removal of Pb(II) and Cd(II) ions from water bodies of Ukraine by natural aluminosilicates

<jats:p>The article summarizes the results of domestic and foreign studies on the sorption removal of Pb(II) and Cd(II) ions by natural aluminosilicates from water systems and justifies their application for water bodies of Ukraine. The sorption potential of natural zeolites (clinoptilolite) and clay minerals (saponite, bentonite/montmorillonite) is analyzed, taking into account key hydrochemical factors: pH, ionic strength, competitive cations (Ca2+, Mg2+, Na+, K+) and dissolved organic matter. It is shown that two-stage kinetics with rapid initial binding of metals and subsequent deceleration to quasi-equilibrium are typical for zeolites; the use of the Elovich model indicates the energy heterogeneity of active centers and the contribution of chemisorption interactions. Equilibrium patterns are considered through Langmuir and Freundlich isotherms, which allows comparing indicative parameters of sorption capacity and process intensity for different types of aluminosilicates. The role of organic ligands is revealed, which change the forms of existence of Pb(II)/Cd(II) in water and can affect the accessibility of cations to ion-exchange positions and surface functional groups. It is established that activation and polymer functionalization of saponite clays increases the sorption capacity and stability of metal fixation, which is critical at low concentrations of pollutants and variable composition of natural waters. The feasibility of using natural zeolites as basic low-cost sorbents with possible combination with modified clay materials is substantiated. The need to optimize the sorbent-water contact regime in static and filtration schemes and analytical control of residual Pb and Cd concentrations to minimize the risk of secondary release is emphasized. The generalizations are suitable for the selection of sorbents and the prediction of the efficiency of water purification in Ukraine.</jats:p>