Sorption Capacity of Synthetic Aluminosilicates of the Kaolinite Group of Various Morphology

Hydrosilicates of the kaolinite group (Al2Si2O5(OH)4 · nH2O) with spherical, nanotubular, and platy particle shapes are synthesized in hydrothermal conditions. The morphology and size of the particles, as well as the porous-textural characteristics, are studied by scanning electron microscopy (SEM) and low-temperature nitrogen absorption. The sorption capacity of the samples relative to the cationic and anionic dyes is investigated on the example of methylene blue and carmoisine. A comparative analysis is conducted for the characteristics of synthetic aluminosilicates and their natural analogs: nanotubular halloysite and kaolinite with platy particles. It is shown that characteristics such as porosity (diameter and volume of pores) and the specific surface area (from 11 m2/g for platy to 470 m2/g for spherical particles) can differ among kaolinite subgroup aluminosilicates having a different morphology. It is shown that the synthetic aluminosilicate with spherical particles (dav = 300 nm) is an effective universal sorbent of differently charged ions from aqueous solutions and its characteristics are better than for structural analogs and synthetic aluminosilicates of a different morphology.