Cysteine modified silica submicrospheres as a new sorbent for preconcentration of Cd (II) and Pb (II)

In this research, submicronsized silica (SiO2) spheres with uniform spherical morphology are grown using the Stöber sol-gel process and subsequently, functionalized with (3-aminopropyl)-trimethoxysilane (APS). These spheres are further modified by chemical binding with L-cysteine (SiO2-CYS). The composition, structure, morphology and surface properties of the particles obtained are characterized by using elemental analysis, SEM, XRD, Zeta potential and N2 adsorption measurements. Experiments performed showed that SiO2-CYS particles permit fast and quantitative sorption of Cd (II) and Pb (II) in the pH range 7-8 and could be used for the separation and preconcentration of Cd (II) and Pb (II) in water samples. Sorption procedure developed is characterized with high concentration factors and ensures quantification of 0.01 μg/L Cd and 0.1 μg/L Pb in various types of water samples. Relative standard deviation for the concentration range 0.01–1 μg/L Cd and 0.1–10 μg/L Pb varied between 4 and 11% for both elements. Analytical method is applied for the determination of Cd and Pb in river, lake and sea water and verified by parallel analysis using ICP-MS