Determination of lead and cadmium by magnetic solid-phase extraction (MSPE) using Co3O4@Fe3O4 nanoflowers and flame atomic absorption spectrometry (FAAS)

Heavy metal ions penetrate wastewater and clean water sources, leading to environmental pollution which adversely affecting human health. The determination and extraction of metal ions help to prevent unwanted effects on the environment and human health. Solid phase extraction method is used for the removal of heavy metal ions. Such method is rapid, reliable and affordable method which provide high recovery rate. For this purpose, cobalt(II/III) oxide@iron(II/III) oxide (Co3O4@Fe3O4) core-shell composite nanoflowers were fabricated via hydrothermal synthesis for the recovery of heavy metal ions (Pb2+ and Cd2+). X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometry (VSM) were used in the chemical and structural characterization of Co3O4@Fe3O4. Flame atomic absorption spectrometry (FAAS) was used for the determination of total metal content. In our work, optimum conditions for heavy metal on recovery such as eluent concentration, eluent type, pH, adsorbent amount, solution volume, sonication duration, were studied. As a result of these studies, quantitative recovery of analyte ions was obtained at pH 7.5. Quantitative recovery of Pb2+ ions was observed with 20 mL 1 M HNO3 solution as eluent and 100 mg amount of adsorbent while, they were found for Cd2+ ion recovery with 5 mL 1 M HNO3 solution as eluent and 200 mg amount of adsorbent. The highest recovery rates were found to be 99.6% and 99.9% for Pb2+ and Cd2+ heavy metal ions, respectively.