Adsorption characteristics of Cu2+ on CeO2/SiO2 nanomaterials based on rice husk and its application to pre-concentration and determination in food samples

We investigate a new CeO 2 /SiO 2 nanocomposite based on nanosilica rice husk for adsorption of Cu 2+ and apply it to pre-concentration and determination of food samples. The CeO 2 /SiO 2 material was characterized by XRD, EDS, TEM, BET, and zeta potential measurements. The selected conditions for Cu 2+ adsorption on CeO 2 /SiO 2 were pH 6 and CeO 2 /SiO 2 dosage 5 mg/mL. Adsorption isotherms of Cu 2+ on CeO 2 /SiO 2 were reasonably fitted by a Freundlich model. Maximum adsorption capacity of Cu 2+ on the CeO 2 /SiO 2 nanocomposite was 50.2 mg/g, greater than common adsorbents. The effect of other cations on Cu 2+ adsorption on CeO 2 /SiO 2 was insignificant. Electrostatic interaction between Cu 2+ and the negatively charged CeO 2 /SiO 2 surface controlled adsorption. The application of Cu 2+ adsorption on CeO 2 /SiO 2 for pre-concentration and determination by flame atomic absorption spectroscopy (F-AAS) achieved excellent results in determining heavy metal content in some food samples.