Effect of Dispersibility of Natural Sorbents on Their Sorption Activity for Cd(II), Pb(II), and Cu(II) Ions

Abstract

The effect of the degree of dispersion of sorbent particles derived from natural minerals (vermiculite and perlite) on their sorption properties towards heavy metal ions Cd(II),Cu(II), and Pb(II) is studied. The particle sizes of the sorbents vary in the range from submicrons to nanometers (from 250 μm to 100 nm), using a range of dispersion methods (grinding using centrifuge and planetary ball mills),which result in a reduction of the particle size by 1.5–100 times. It is found that the sorption of the examined metal ions on the surface of all the substates can be described by the Langmuir absorption model, regardless of the degree of sorbent dispersion. The low values of the heat of the sorption for ions studied indicate the physical nature of sorption. An increase in the dispersion degree of the sorbents contributed to a significant increase in the sorption activity of dispersed particles of vermiculite and perlite towards to the ions studied (up to 2-fold increase in the sorption degree values). The optimization of the sorption conditions made it possible to achieve high sorption efficiency with the sorption degree ~99.9% towards Cd(II), Cu(II), and Pb(II) ions at a 10-4 mol/L ion concentration and close to neutral conditions at ambient temperature.