Selective sorbent enrichment of nickel ions from aqueous solutions using a hierarchically hybrid organic-inorganic polymer based on double imprinting concept

Abstract

This study involves the preparation of an ion imprinted organic-inorganic polymer (IIP) for selective sorbent enrichment of Ni2+ from aqueous solutions with further determination by GF AAS. The hybrid polymeric network was prepared from a mixture of 2-aminoethyl- 3-aminobutylmethyldimethoxysilane as functional monomer, and tetraethoxysilane as crosslinking agent, containing Ni2+ and cetyltrimethylammonium bromide as templates. The polymers were characterized by IR, TG and SEM. The maximum adsorptive capacity of IIP towards Ni2+ ions, determined by linear Langmuir model, was found to be 5.44 mg g-1. When the selectivity coefficient of IIP was compared with the selectivity coefficient of NIP (non imprinted polymer) and IIP2 (ion imprinted polymer in the absence of surfactant), from the binary mixtures of Ni2+/Cu2+, Ni2+/Co2+, Ni2+/Cd2+ and Ni2+/Zn2+, values of relative selectivity coefficient (k') were 36.54 and 3.55, 1.22 and 2.03, 4.43 and 1.42, 28.60 and 1.74, respectively, demonstrating higher selectivity of IIP for Ni2+ ions. The proposed method provided a limit of detection of 0.16 µg L-1 and was successfully applied for Ni2+ determination in spiked water samples and in a phytoterapic product (Gingko Biloba) with satisfactory recovery values.