ИСТИНА

Heavy metals are considered priority pollutants of water and soil, especially in urban areas. Natural organic matter (OM) serves as a natural barrier against the spread of these toxins, forming strong complexes with metals and reducing their mobility and toxicity. Humic substances (HS) play a major role among the OM components. Modern nature-like groundwater treatment technology that mimics natural geochemical barriers is permeable reaction barriers (PRBs). The traditional method of installing PRBs requires removal of a large volume of contaminated soil, which is not always convenient. A more promising option is injection PRBs, which require the use of special liquids capable of sorbing in significant quantities on mineral substrates. Such a liquid can be based on polyelectrolyte complexes of HS with aminoorganosilanes. The actual task is to study the sorption parameters of this complex on mineral substrates. In this work, polyelectrolyte complexes of HS and (3-Aminopropyl)triethoxysilane (APTES) with different mass ratio were prepared. The kinetics of their adsorption on silica gel was studied and the adsorption parameters were determined. The sorption experiments were carried out in phosphate buffer medium (0.03M, pH 6) due to the maximum stability of these compositions in aqueous medium. The time of the sorption experiment was 4 hours, since kinetic experiments showed that this time is sufficient for the establishment of sorption equilibrium. Sorption isotherms were plotted in the range of concentrations of polyelectrolyte complex APTES/HS in solution from 5mg/l to 1200mg/l, because at higher concentrations aggregation and subsequent sedimentation of the whole composition is observed. As a result, it was found that the sorption isotherms of APTES complexes are best described by the shifted quadratic Langmuir equation. The KL adsorption constants found were 1.8 ± 0.2, 20 ± 2, 11 ± 1, 36 ± 2, 260 ± 30 l/kg for samples with APTES/HS mass ratio of 0.5, 0.75, 1, 2, 3, respectively, indicating the dependence of sorption parameters on the composition of the complexes due to the increasing affinity of adsorbate to adsorbent Acknowledgements. This research was carried out within the framework of the state task “Ecology” (CITIS no. 122040600057-3)