Template Synthesis of Iminodiacetic Acid Polysiloxane Immobilized Ligand Systems and Their Metal Uptake Capacity

Abstract

Two different routes for the synthesis of insoluble porous solid functionalized ligand system bearing iminodiacetic acid chelating ligand of the general formula P-(CH2)3N-(CH2COOH)2 (where P- represents [Si-O]n polysiloxane network) were achieved by sol-gel template method in presence of CTAB surfactant to formed porous materials. The first route was achieved by the modification of 3-aminopropylpolysiloxane with ethylchloroacetate, followed by hydrolysis with HCl to form the polysiloxane iminodiacetic acid ligand system; P-(CH2)3N-(CH2COOH)2 (P-IDA-I). The second route was achieved by the reaction of diethyliminodiacetate with 3-iodopropylpolysiloxane to form immobilized-polysiloxane diethyliminodiacetate system. The diethyliminodiacetate polysiloxane immobilized ligand system was then hydrolyzed by HCl to form the iminodiacetic acid ligand system P-(CH2)3N-(CH2COOH)2 (P-IDA-II). Elemental analysis, 13C NMR, XPS and FTIR results showed that the surfactant have improved the silica network structure and increased the metal uptake capacity of the ligand system. Thermogravimetric analysis studies showed significant stability of the immobilized ligand systems upon complexation with metal ions. The new functionalized ligand systems exhibit high capacities for uptake of the metal ions (Ni2+, Cu2+ and Pb2+).