Transformation of the structural organization of clay sediments and soils under the impact of polyelectrolytes

Abstract

The effects of polyacrylic acid (PAAc) and polyacrylamide (PAA) adsorption by quartz sand, montmorillonite, kaolinite, gray forest soil, and chernozem on the texture of the sorbents were studied. It was shown that the polymolecular adsorption was typical of the applied polyelectrolytes. The addition of PAA in a concentration of 0.05% to the solution resulted in consolidation of the sediments with a decrease in their volume. In the case of montmorillonite, a loose gel precipitate formed; its volume decreased by about 6% during the experiment. The adsorption of polyelectrolytes slightly affected the average radii, total surface area, and volume of the pore space (within 4–20%). The transformation of the surface of minerals and soils under the action of polyelectrolytes resulted in a significant change in the differential pore volume. The number of pores of about 0.0014 μm in size hardly changed at all. However, wider pores (0.011–0.45 μm) appeared. The adsorption of PAAc resulted in the appearance of wide pores (1.6–22.0 μm), and the adsorption of PAA resulted in the appearance of two narrow classes of micropores. A much more even distribution of differential porosity in the range of 3.6–4.5 μm was revealed. Thus, the transformation of the surface of adsorbents by polyelectrolytes led to changes in the pore-size distribution.