An Innovative Nanosorbent Based on ZnO@Ag2O@Fe3O4 Nanocomposite- for Extraction and Preconcentration of Cd(II) Ions from Water Samples

In this study, a ZnO@Ag2O@Fe3O4 nanocomposite as an innovative magnetic solid phase extraction agent was introduced. The structural and morphological properties of the as-prepared nano-sorbent were characterized using X-ray diffraction analysis, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and nitrogen adsorption–desorption techniques. The synthesized magnetic nano-sorbent was applied for extraction and pre-concentration of Cd(II) ions from water samples. The as-prepared nano-sorbent with the magnetism property was easily manipulated by a magnet. Factors affecting the extraction of the Cd(II) ions from aqueous solutions were investigated and optimized conditions were reported. Under optimum conditions, linear concentration range of 0.1–10 ng mL–1 with a correlation coefficient of 0.9918 was obtained for Cd(II) ions. The detection limit and enrichment factor for cadmium are 0.03 ng mL‒1 and 200, respectively. The intra- and inter-day relative standard deviations (at 4 ng mL−1 Cd(II) ion concentration and n=6) are 1.8 and 2.6 %, respectively. The maximum sorption capacity of the nano-sorbent for cadmium is 48 mg g‒1. The accuracy of the method was checked by the analysis of the standard reference material NIST SRM 1643e, and successfully applied to determine cadmium in several water and wastewater samples with relative recovery values in the range of 98–102 % for the spiked samples.