Functionalization of magnetic hollow porous oval shape NiFe2O4 as a highly selective sorbent for the simultaneous determination of five heavy metals in real samples

•Amino/carboxy functionalized magnetic hollow porous oval-shape NiFe2O4 was prepared.•Constructed hollow porous NiFe2O4 is good for targets diffusion into reaction sites.•MHPO-NiFe2O4 shows good dispersibility and adsorption capacity for five heavy metals.•The developed MSPE-ICP-OES method was successfully used for analysis of five metals.•The propose method significantly improved detection limit of metal ions.

In this study, a functionalized magnetic hollow porous oval-shape NiFe2O4 (MHPO-NiFe2O4) was designed by a facile synthesis procedure, and employed as magnetic solid phase extraction (MSPE) material to extract several heavy metal ions. As-prepared MHPO-NiFe2O4 exhibited superior adsorption capacities of 20.17, 16.64, 16.82, 9.69 and 16.58 mg g−1, for Cu(II), Cd(II), Cr(III), Co(II) and Zn(II), and was then used to detect these heavy metals elements in real samples by combining with inductively coupled plasma optical emission spectroscopy (ICP-OES). The possible mechanism of the enrichment of heavy metals ions on MHPO-NiFe2O4 was proposed, which involved the dominant adsorption and desorption. The detection limits were as low as 0.015, 0.13, 0.062, 0.035 and 0.46 μg L−1 for Cu(II), Cd(II), Cr(III), Co(II) and Zn(II), respectively. A good repeatability was obtained with the relative standard deviation (RSD) of 3.87%. Moreover, the method was successfully utilized for the analysis of five heavy metals in real samples (cabbage, lettuce, apple, seawater), with satisfactory recoveries in the range of 92–108%.

Graphical abstractThis figure is a brief description of the adsorbent synthesis and extraction processes.Figure optionsDownload full-size imageDownload as PowerPoint slide