Sorption of Heavy Metal Ions by Composite Materials Based on Polycarboxylic Acids and Bentonite Clay

Abstract

The paper shows the study results of sorption capacities of composite gels based on polyacrylic and polymethacrylic acids with bentonite clay as the mineral filler concerning heavy metal ions (Pb^+2, Cu⁺², Ni⁺², Zn⁺², Fe⁺², Cd⁺²). The binding of metal ions to gels occurs through the formation of electrostatic bonds between the charged surface of bentonite clay and ionogenic functional groups of polymers in the composition, as well as the coordination bonds between metal ions and unshared pairs of oxygen electrons in the functional groups of polymers. The gel swelling degree decreases in metal solutions with increasing metals concentration and the content of BC in the composite. The sorption and desorption of heavy metal ions from the polymer-clay composites from model solutions and samples of industrial wastewater from the Kazakhstani metallurgical plants were evaluated. The adjustment of the pH, the temperature of the medium and the clay content in the composite leads to increasing the degree of sorption and achieving regeneration of the used composite gels in certain media. The data obtained testify to the prospects of using these composites as effective sorbents of heavy metals from industrial wastewaters expanding the range of composite materials for wastewater treatment.