Development of a mineralogical matrix at the adsorption of polyelectrolytes on soil minerals and soils

Abstract

The formation of the adsorption layers of polyelectrolytes (PEs) with the development of a mineralogical matrix on the surface of soil minerals and soils (kaolinite, montmorillonite, quartz sand, gray forest soil, and a chernozem) were established on the basis of direct measurements and IR spectroscopy. The differences in the adsorption kinetics of polyacrylamide (PAM) and polyacrylic acid (PAA) were revealed depending on the mineral nature, which were confirmed by the calculated values of the effective adsorption constants. It was found that the limit values of the PAM and PAA adsorption derived from experimental measurements for all the minerals were significantly higher than the values calculated for the formation of a monomolecular layer, which indicated adsorption on the surface of not only separate macromolecules but also secondary PE structures such as packets or fibrils. The IR spectroscopy studies confirmed the differences in the adsorption mechanism of PEs on soil minerals (from physical adsorption to chemisorption with the formation of surface compounds due to polar groups of PEs and surface groups of mineral particles). As a result, a cluster-matrix structure controlling the physicochemical properties of the modified surface was developed on the surface of natural aluminosilicates and soils.