Solid Phase Extraction of Pb(II) and Cd(II) in Food, Soil, and Water Samples Based on 1-(2-Pyridylazo)-2-Naphthol-Functionalized Organic–Inorganic Mesoporous Material with the aid of Experimental Design Methodology

Abstract

An effective sorbent of 1-(2-Pyridylazo)-2-naphthol-functionalized mesoporous silica has been prepared to simultaneous separation and preconcentration of lead and cadmium ions in aqueous solution. Structural characterization of 1-(2-Pyridylazo)-2-naphthol-functionalized organic–inorganic hybrid mesoporous materials was conducted by Fourier transform infrared spectroscopy, transmission electron microscopy, N2 adsorption–desorption measurement, X-ray diffraction, and elemental and thermal analysis, which confirmed the successful grafting of organic moiety on mesoporous silica. The affecting parameters on adsorption and desorption steps were optimized by Box-Behnken design through response surface methodology. Three variables (pH value, sorption time, and amount of the sorbent) were selected as the main factors affecting sorption step, while four variables (type of eluent, eluent volume, eluent concentration, and elution time) were selected for desorption step in the optimization study. The optimized values by this optimization method were 10 mg, 8 min, 6.3, HCl, 1.6 mL, 1.2 mol L−l HCl, and 10 min, for amount of sorbent, sorption time, pH of solution, type, volume, and concentration of the eluent, and elution time, respectively. Under the optimized conditions, the detection limits of the proposed method for lead and cadmium ions were found to be 0.9 and 0.04 μg L−1, respectively, while the relative standard deviation (RSD) for five replicate measurements was calculated to be <3 % for both ions. For proving that the proposed method is reliable, a wide range of food, soil, and water samples with different and complex matrixes was used.