This article concerns the effect of the chemical modification of short flax fiber on its sorption properties for heavy metal ions. The main purpose of the modification was to achieve the oxidation of flax cellulose with sodium metaperiodate to form dialdehyde cellulose. Additionally, the research shows the subsequent interaction of dialdehyde cellulose with 1-amino-8-hydroxynaphthalene-3,6-disulfonic acid and its transformation into a derivative capable of forming chelate complexes with heavy metal ions. Additionally, this article presents the results of equilibrium and kinetics studies of the sorption of Cu(II), Cd(II), and Fe(II) ions from aqueous solutions by primary and modified cellulose sorbents. SEM spectra indicate changes in the surface structure of the modified sorbents compared to the original one. IR spectra show the appearance of amino- and sulfogroups in short flax fibers in the process of their modification. The research revealed the efficiency of the method and the possibility of its use for the purification of aqueous solutions from heavy metal ions in industrial processes.

A mechanical activation of chitin suspended in water has been employed under conditions of a combined impact of cavitation and high shear stresses realized in a rotor-pulse device. For chitin samples that underwent preliminary activation for 5–20 s, the value of sorption capacity toward copper ions increased twoto fourfold in dependence on the treatment duration as compared to the initial sample. The experimental data corroborating that the main factors of mechanical activation are the increase of the specific surface area, porosity, and particle-chitin amorphization are presented. It has been established that the increase of the duration of mechanical treatment over the experimentally determined optimal value yields a decrease of the activation effect, which is related to the processes of restructuring and recrystallization. It has been shown that the Langmuir model allows rather adequate description of the sorption process with the correlation coefficient of 0.98–0.99.

The specific adsorption of heavy metal ions on hydrophilic monodentate biosorbent sites was studied. The solvation and coordination mechanism of cation distribution in heterophase system was suggested. Bivalent metal cation desorption mechanism affected by monovalent metal salts (NaCl) was represented in the form of cation-cation resolvation on monodentate sorbent sites, involving ion pairs of hydrated cations and counter ions (anions). The metal ion degree of extraction was found to decrease by 20%, when the solution/sorbent module increased from 75 to 1000. Heavy metal ion sorption by polysaccharide sorbent was identified as exothermic process. The estimated values of ΔH and ΔS enabled to consider sorption of metal cations on polysaccharide sorbent as specific reversible adsorption.