Extraction of gold, palladium and silver ions using organically modified silica-coated magnetic nanoparticles and silica gel as a sorbent

Two new adsorbents were synthesized by covalently grafting 2,3-Bis(2-formylphenoxy)-propan-1-ol (BH) onto the surface of silica-coated magnetic nanoparticles and silica gel by a conventional method and a vice-versa method. The morphology and properties of the adsorbents were characterized by FT-IR, XRD, SEM, TEM, VSM, TGA, UV-Vis, Optical microscope and DLS. The materials are shown to be effective adsorbents for the selective extraction of the ions of Au(III), Pd(II) and Ag(I) from aqueous mixed metal ions solution also containing Cu(II), Co(II), Ni(II), Zn(II) and Pb(II). Syringe and batch techniques are compared. The ions can be desorbed with 0.5 M HCl and quantified by FAAS. The maximum adsorption capacity of the MN-Si-NH2-BH and Si-NH2-BH were determined to be 257, 197 mg·g−1 for Au(III), 311, 191 mg·g−1 for Ag(I) and 301, 222 mg·g−1 for Pd(II), respectively. The detection limits (for n = 15 and at an S/N ratio of 2 blank standard deviations) are 0.12, 0.28, and 0.17 μg·L−1 for Au(III), Pd(II) and Ag(I), respectively.