Solid phase extraction of Au(III) by bis(3-aminopropyl)amine bonded silica gel

In this study, bis(3-aminoproypl)amine bonded silica gel (BAPA-SG) was synthesized and used as an adsorbent for solid phase extraction of Au (III) ions from aqueous solutions. Throughout the study, flame atomic absorption spectrometer was used for the determination of Au(III) ion concentrations. The effects of pH, contact time, chloride concentration and initial Au(III) concentration on Au(III) adsorption were investigated and optimized in the experiments performed by the batch adsorption method. Au(III) adsorption increased by decreasing of sample solution acidity and reached the maximum level at pH 3.0. The equilibrium time of Au(III) adsorption was determined to be 4 hours. It was observed that the increase of chloride concentration reduced Au(III) adsorption. The Au (III) adsorption capacity of BAPA-SG was calculated as 52.4 mg g-1 at pH 2.0, and 107.5 mg g-1 at pH 3.0. In column extraction and enrichment studies, the effective factors such as solution pH, solution volume, flow rate of sample, type and volume of the eluent solution and levels of some alkaline and heavy metals were examined and optimized. It was found that Au (III) ions were quantitatively recovered using the BAPA-SG filled column by passing of 500 mL of the sample solution at pH 2.0 with 5 mL/min flow rate thorough the column and then elution of adsorbed A(III) ions with 5.0 mL of 1% thiourea in 0.1 M HCl solution.