Novel dendrimer-functionalized SPIONs as adsorbent agents for effective removal of Cr(VI) ions.

Due to its toxic effects, hexavalent chromium (Cr(VI)) has mutagenic and carcinogenic impacts on living systems. Thus, developing effective adsorbents that can quickly adsorb heavy metals is crucial for the removal process. Thanks to their outstanding and novel characteristics, superparamagnetic iron oxide nanoparticles (SPIONs) are novel structures used in various applications. For this reason, novel dendrimer-functionalized SPIONs are used for the extraction and enrichment of Cr(VI). SPIONs were synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM) where their chemical compositions, crystal structures, and magnetic properties were assessed in detail. Various parameters such as the amount of adsorbent, pH, the type and concentration of eluent, adsorption time, and coexisting ions were evaluated to find the best adsorption conditions for SPIONs, where flame atomic absorption spectroscopy was used as the main investigation tool. Under the optimum conditions, the synthesized adsorbent showed an excellent selectivity towards Cr(VI) with an exceptional enrichment factor of 1403 in the presence of other interfering ions. The calibration graph was linear in the range of 0.25-2000 µg L^-1 (R² = 0.9992), and the limit of detection (LOD, 3δ/m) was 0.075 µg L^-1 for Cr(VI). The relative standard deviation (RSD, n = 6) of the work for Cr(VI) was 2.8%. The proposed method was employed to real-life samples, including water, honey, and hardaliye (a traditional fermented grape juice).