Preconcentration and separation of palladium using solid phase extraction by benzoylthiourea immobilized silica

Purpose of this study is preconcentration and separation of palladium using solid phase extraction method by silica modified with benzoylthiourea. Benzoylthiourea based silica was synthesized at three steps and was characterized by IR spectrometry method. The optimum conditions for sorption and desorption of palladium (II) ion by the progressed silica sorbent was investigated. High sorption was observed at strong asidic medium and also up to pH 6. The best desorption solution were determined as thiourea in HCl and KCN solutions. The flow rate for sorption and desorption was optimized as 2 mL/min. The synthesized silica sorbent was used successfully for the separation and enrichment of Pd (II), additionally which has a good chemical stability, high reusability and faster rate of equilibrium. The effects of alkaline metals, common anions and some heavy metal ions as interferents were discussed. The procedure proposed allowed the determination with detection limit 2.3 ng Pd/L and relative standard deviation (RSD p e r c e n t a g e o f ) 1.68 for 0.25 m i c r o g r a m Pd/mL. The preconcentration factors for 100 and 1000 ng/mL were 142 and 91, respectively. The enrichment procedure showed a linear calibration curve within concentration range from 0.006 to 1.5 m i c r o g r a m Pd/mL. Moreover, this procedure was applied to synthetic and alumina and active carbon based palladium catalysts to prove the reliability of the proposed preconcentration method.