Preparation of ethylenediaminetriacetic acid silica-gel immobilised ligand system and its application for trace metal analysis in aqueous samples

Abstract

This article reports on the preparation of porous solid ethylenediaminetriacetic acid functionalised silica-gel (S-EDTA) of the general formula S-(CH2)3N(CH2COOH)-(CH2)2-N(CH2COOH)2 (where S represents [Si–O] n ). This was prepared by modification of 3-(2-aminoethylaminopropyl)trimethoxysilane with ethyl chloroacetate followed by polycondensation with tetraethylorthosilicate via the sol–gel process. The immobilised ethylenediaminetriacetic acid ligand system (S-EDTA) was characterised by FTIR, 13C CS-MAS NMR and XPS spectroscopic techniques. The resulting functionalised ligand system showed high potential to extract and separate Co2+, Ni2+ and Cu2+ metal ions from aqueous samples. The saturation sorption capacities of Co2+, Ni2+ and Cu2+ metal ions were 77.6, 89.1 and 99.4 mg g−1, respectively. The optimum separation pH values were 4.5 and 4 for Co(II) and Ni(II), respectively, while a solution of 0.1 mol L−1 HNO3 (pH = 1) was used to elute Cu(II).