Abstract
Ion-imprinted polymers (IIPs) have received much attention in the fields of separation and purification. Nevertheless, selectivity of IIPs for trace target ions in complicated matrix remains a challenge. In this work, a cadmium magnetic ion-imprinted polymer (MIIP) was synthesized via surface imprinting, using methacrylic acid and acrylamide as dual functional monomers, vinyltrimethoxysilane as ligand, Fe3O4@SiO2 as support, azodiisobutyronitrile as initiator, and ethylene glycol dimethacrylate as crosslinker. The MIIP was characterized by transmission electron microscopy, infrared spectroscopy, thermal gravimetric analysis, and a vibrating sample magnetometer. The maximum adsorption capacities of the MIIP and magnetic non-imprinted polymer for Cd(II) were 46.8 and 14.7 mg·g−1, respectively. The selectivity factors of Pb(II), Cu(II), and Ni(II) were 3.17, 2.97, and 2.57, respectively, which were greater than 1. The adsorption behavior of Cd(II) followed the Freundlich isotherm and a pseudo second order model. The MIIP was successfully used for the selective extraction and determination of trace Cd(II) in representative rice samples. The limit of detection and recovery of the method was 0.05 µg·L−1 and 80–103%, respectively, with a relative standard deviation less than 4.8%. This study shows that MIIP provides an attractive strategy for heavy metal detection.
Highlights
Cadmium is one of the most toxic heavy metals and causes serious harm to human health via the food chain [1,2]
A wide range of analytical techniques to evaluate cadmium(II) in the spiked or real samples have been reported in recent years, including atomic absorption spectrometry (AAS) [4], inductively coupled plasma mass spectrometry (ICP-MS) [5], electrochemical sensor [6]
If ion-imprinted polymer materials are chemically grafted onto Fe3 O4 nanoparticles, which have unique magnetic properties and high surface area, easy separation and selective extraction can be achieved with the application of an external magnetic field
Summary
Cadmium is one of the most toxic heavy metals and causes serious harm to human health via the food chain [1,2]. Ion-imprinted polymers (IIPs) are becoming promising solid-phase extraction (SPE) sorbents and have gained much attention because of their outstanding advantages such as high selectivity, large adsorption capacity, and good reusability [12,13]. Ion-imprinted polymers for selective extraction and determination in food and environmental samples. A Ni(II) ion-imprinted polymer prepared by Saraji et al [15] was employed as a sorbent in a solid-phase extraction column to preconcentrate trace nickel with satisfactory results. If ion-imprinted polymer materials are chemically grafted onto Fe3 O4 nanoparticles, which have unique magnetic properties and high surface area, easy separation and selective extraction can be achieved with the application of an external magnetic field. Despite the emerged interests in magnetic ion imprinting techniques, single functional monomers are widely and generally used for preparing imprinted polymers and thereby result in low selectivity. The characterization, kinetics, isotherm model of Cd(II) adsorption process, selectivity, and application of this new magnetic sorbent are discussed in this study
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