Synthesis, Characterization and Selective Metal Binding Properties of Physically Adsorbed 2-Thiouracil on the Surface of Porous Silica and Alumina

Abstract.

The physical adsorption of 2-hydroxy-2-mercaptopyrimidine (2-thiouracil) on the surface of porous silica gel and basic alumina is studied and described. Four silica and alumina materials were identified on the basis of surface coverage determination by thermal desorption method. Modified aluminas were found to be physically adsorbed with 2-thiouracil by 0.14, 0.54, and 0.43–1.63 mmol g⁻¹. Modified silica materials (I–IV) were identified by adsorption of 2-thiouracil (0.344–0.446 mmol g⁻¹). The metal sorption, binding and selectivity properties of these modified alumina and silica materials were studied and evaluated by a series of di- and trivalent metal ions. Aluminas (II–IV) were found to have high capacity in selective extraction of cadmium (II) from aqueous solutions compared to other tested metal ions. The highest metal capacity (1.0 mmol g⁻¹) was found for cadmium (II) on modified aluminas (IV). Potential application of the modified aluminas (I–IV) for selective removal and extraction of 1.0 ng mL⁻¹ of cadmium (II) from natural seawater samples was performed and compared with the modified silicas (I–IV). The modified aluminas (II–IV) showed a significantly higher capacity than the modified silicas for cadmium (II) with an average percentage recovery value of 97.8±0.4%. The matrix effect of seawater was found to play an insignificant role in the atomic absorption spectrophotometric analysis of cadmium (II).