Adsorption of Zn²⁺ and Cd²⁺ from Aqueous Solution onto a Carbon Sorbent Containing a Pyrimidine–Polyamine Conjugate as Ion Receptor

Abstract

Abstract The compound N ‐(4‐amino‐1‐methyl‐5‐nitroso‐6‐oxo‐1,6‐di‐hydropyrimidin‐2‐yl)‐ N '‐[bis(2‐aminoethyl)]ethylenedi‐amine (HL) was synthesised and structurally characterised by analytical methods and 1 H, 13 C and 15 N NMR spectroscopy. The protonation of HL and its coordinating ability towards Zn 2+ and Cd 2+ ions in water solution were also studied by potentiometric methods and UV/Visible and 1 H‐ 13 C NMR spectroscopy. The molecular structures of [H 3 L] 2+ [CdI 4 ] 2– · 2H 2 O and [(Cl 3 Zn)(μ‐Cl){Zn(μ 2 ‐HL)}] 2 · 2.5H 2 O were solved by single‐crystal X‐ray diffraction methods. On the basis of these data, the performance of HL anchored to activated carbon (AC) was evaluated as a molecular receptor for Zn 2+ and Cd 2+ metal ions in aqueous solution. This was done by a comparative study of the adsorption capacity of the adsorbents AC alone and HL anchored on the AC (AC‐HL) for these metal ions and by a structural study of the AC‐HL, AC‐HL‐Zn 2+ and AC‐HL‐Cd 2+ solid phases by XPS and IR spectroscopy . (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)