Magnetic separation of uranium VI using iron oxide nanoparticles and its spectrophotometric determination in environmental water samples

A trace solid phase extraction method based on magnetic iron oxide nanoparticles (MINPs) modified by sodium dodecyl sulfate (SDS) was developed for the preconcentration and determination of uranium (VI) ions. Oxine (8- quinolinol) was used as chelating agent and the factors influencing the complex formation and extraction of uranium were optimized. Under optimum conditions, negative head groups of SDS would interact with the positive surface of MINPsto form a double layer. Then oxine- uranyl complexes would be extracted in the hydrocarbonic tails of SDS by hydrophobic force.5 mL ethanol containing 1 % NH3 was used as desorbing agent and finally, the absorbance of eluent was measured for the determination ofuranium, against a blank at 370 nm by Uv-Vis spectrophotometry. The analytical curve was found to be linear in the range of 3.0- 300 ng mL-1 with adetection limit of 0.8 ng mL-1. The method was successfully applied to the determination of uranium in tap, mineral, river and sea watersamples with spike recoveries ranging from 93 – 108 %. This method was also applied for the determination of uranium (VI) in the rock samplesand the obtained results were in accordance with ICP-MS method.