The Effect of Preadsorbed Polyelectrolytes on the Surface Properties and Dispersity of Clay Minerals and Soils

Abstract

On the basis of adsorption studies, the characteristics of formation of polyelectrolyte (PE) nanoadsorption layers of an aliphatic structure that creates a mineral–organic matrix on clay minerals and soils (kaolinite, montmorillonite, quartz sand, and gray forest and chernozem soils) surfaces have been revealed. It has been established that the polyacrylamide (PAM) and polyacrylic acid (PAA) adsorption limit values on all minerals are significantly higher than the calculated values for the single-layer formation. This indicates the surface adsorption of not only individual macromolecules, but also of secondary PE structures of types of bundles or fibrils determining the cluster-matrix structure of the modified surface. The study of the electric surface properties (electrophoretic mobility, electrokinetic potential, рН, and electroconductivity) of adsorption-modified PE suspensions of minerals and soils has corroborated that there are differences in the adsorption mechanism, ranging from physical to chemisorption with the formation of surface compounds, as a result of both differences between PE polar groups and the mineral type. It has been demonstrated that the mineral and soil surface modification by organic substances differently affects the dispersity, porosity, mean pore radii, total surface area, and pore volume in the direction of both an increase and decrease in size. Here, this results in significant changes in the differential pore volume and more homogeneous pore size distribution.