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New adsorbent material was obtained by modification of commercial Amberlite XAD7 with thiourea that represents a non-toxic, cheap and environmentally friendly extractant. Prepared adsorbent was used for removal of neodymium ions from aqueous solutions. Thiourea modified Amberlite involved in this study shows good adsorption capacities (74.3 mg/g) and excellent efficiency during Nd removal process. In order to elucidate the mechanism of the Nd adsorption process kinetic, thermodynamic and equilibrium studies were performed, establishing this way which kinetic model better describes the Nd adsorption process. Moreover the thermodynamic studies prove that the Nd adsorption on thiourea modified Amberlite XAD7 is an endothermic and spontaneous process.

New adsorbent materials using different doping methods were obtained. Magnesium silicate was doped with environmentally friendly extractants like sodium β-glycerophosphate, tetraethylammonium bromide, and thiourea. The methods used were the dry method, the ultrasound unconventional method, and a new method, the pellicular vacuum solvent vaporization. The doped materials were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and determination of the specific surface area (BET). The usefulness of these materials and their performances were studied on the adsorption of rare earth elements Eu(III), Nd(III), and La(III). The best adsorption capacity of 16 mg/g was obtained for Eu(III) on magnesium silicate doped with thiourea. Nonlinear regression analysis of adsorption data was made employing Langmuir, Freundlich and Sips models.

A novel, cysteine-containing fluorescent hexapeptide, N-acetyl-Tyr-Cys-Ser-Ser-Cys-Tyr– (YY), targeting Cd(II) ion sensing, was synthesized on various solid supports including two resins, as well as glass and quartz surfaces. The synthesis was based on the Fmoc (9-fluorenylmethoxycarbonyl) and the APTES (3-aminopropyltriethoxysilane) methodologies on the resin and silica supports, respectively. The immobilized ligand, except when coupled to a hydrophobic benzhydrylamine resin, showed a remarkably efficient, pH-dependent Cd(II) capturing ability with a maximum binding capacity around neutral pH. The effect of contact time and metal ion concentration was also studied with a hydrophilic resin supported peptide (YY-NTG). The interaction of YY-NTG with Cd(II) was investigated by pH-potentiometric titrations in aqueous samples containing the resin beads and Cd(II). These studies, together with metal ion capturing experiments under buffer-controlled pH, prove that each immobilized peptide can bind one Cd(II) ion at pH 7.0 in the presence of one equivalent metal ion or metal ion excess. For Cd(II) binding to YY-NTG a notably high, K= 1.3 × 1010apparent stability constant was determined (1:1 metal-to-ligand ratio, pH 7.0). Analytical results suggest that the concentration of Cd(II) can be measured below 200 nM with this silica-supported peptide. The usefulness of the probe was demonstrated by fluorescence spectroscopy.