FORMATION OF NANOCLUSTERS IN THE TRANSITION OF CARBON DIOXIDE TO THE SUPERCRITICAL STATE

Abstract

Supercritical fluid extraction (SFE) with CO2 is widely used to extract biological materials, metal complexes and their isotopes. Supercritical CO2 (SC-CO2) is an environmentally friendly, efficient, and affordable solvent. However, the change in the chemical and physical properties of CO2 in the transition to the supercritical (SC) state has not been studied so far. The paper proposes to consider such a change as a result of the formation of elementary linear, flat or volumetric nanoclusters, from which large nanoclusters can also be formed. Based on the theory of repulsion of valence electron pairs, the geometry of the arrangement of atoms in elementary nanoclusters is described. The change in the chemical and physical properties of CO2 is confirmed by absorption spectra in the IR range for wavelengths of 4.2…4.4 μm in sub- and SC-CO2.