PH dependent separation of uranium by chelation chromatography using pyridine 2,6-dimethanol as a chelator: Single crystal X-ray structural confirmation of the chelated uranium complex

Abstract

A very effective sorbent material which exhibits exceptional capture of hexavalent uranium from other actinides and lanthanides at μg g −1 level, features pyridine 2,6-dimethanol immobilized onto alumina. The maximum sorption capacity for dioxouranium(VI) was found as 1.96 mmol g −1 at pH 3.0. The adsorbed uranium complex was eluted completely by 0.05 mol L −1 (NH 4) 2CO 3 solution and the concentration of hexavalent dioxouranium ion was monitored spectrophotometrically using Arsenazo III. The structure of the chelated uranium complex has been confirmed by single crystal X-ray structure analysis and Fourier transform infrared red (FTIR) spectroscopy. Thermo gravimetric analysis/differential thermo gravimetric analysis (TGA/DTG) of the chelated uranium complex was performed. The method is reproducible with a relative standard deviation (RSD) of 1.2% ( N = 10) and the three sigma detection limits ( N = 15) 1.2 μg mL −1 respectively. A pre-concentration factor, almost 500, for uranium was achieved. Interferences from Th 4+, Mn 2+, Ni 2+ and Cu 2+ ions were masked with ethylene diamine tetra acetic acid (di-sodium salt) (Na 2EDTA) in the aqueous phase. The developed method has been tested for uranium recovery and estimation in some certified reference materials and environmental samples.