Effect of the concentration of chemically immobilized mercaptopropyl groups on the surface of silica gel on the sorption-photometric determination of palladium(II) and silver(I) as their complexes with grafted groups and dithizone

This study examines the effect of the concentration of mercaptopropyl groups chemically immobilized on the surface of silica gel (ranging from 0.18 to 0.76 mmol/g) on the formation and color intensity of Pd(II) complexes with grafted groups, as well as mixed-ligand complexes of palladium(II) and silver(I) with mercaptopropyl groups and dithizone. It was shown that increasing the concentration of immobilized mercaptopropyl groups enhances the color intensity of sorbents containing the same amount of sorbed palladium(II). However, in the case of mixed-ligand complexes with dithizone, increasing the surface concentration of grafted groups leads to a decrease in color intensity. Methods were developed for the sorption-photometric determination of Pd(II) as complexes with grafted groups, and of Pd(II) and Ag(I) as surface mixed-ligand complexes. The study concludes that to achieve low detection limits for metal elements using sorption-photometry in the form of grafted group complexes, the concentration of the grafted groups should be maximized. Conversely, for detection as mixed-ligand complexes with dithizone, the concentration of the grafted groups should be minimized.

chemically modified silica gel, mercaptopropyl groups, palladium, silver, concentration, sorption-photometric determination