Hybrid Amine-Functionalized Titania/Silica Nanoparticles for Solid-Phase Extraction of Lead, Copper, and Zinc from Food and Water Samples: Kinetics and Equilibrium Studies

In the present study, hybrid amine-functionalized titania/silica nanoparticles were employed as a new and novel adsorbent for solid-phase extraction of Pb2+, Cu2+, and Zn2+ ions prior to their determination using flame atomic absorption spectrometry. Under the best conditions (including adsorbent, 0.4 g; eluent, 5.0 mL nitric acid (HNO3), 3.0 mol L-1, 1.0 mL min(-1); and sample, pH 5.0, 3.0 mL min(-1)), detection limits, adsorption capacities, and preconcentration factors were 0.12-0.24 mu g L-1, 7.1-20.7 mg g(-1), and 200, respectively. To predict the adsorption isotherms, different isotherm models were studied and the obtained results showed that the Langmuir model is the most suitable one to explain the experimental data. The kinetics of the reaction followed pseudo-second-order kinetic model. Thermodynamic parameters like free energy (Delta G (0)) and enthalpy (Delta H (0)) confirmed the spontaneous and exothermic nature of the process. The method was successfully applied for determination of the analytes in different food and water samples.