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

A very effective sorbent material which exhibits exceptional capture of hexavalent uranium from other actinides and lanthanides at microg 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))(2)CO(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 microg 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(2)EDTA) in the aqueous phase. The developed method has been tested for uranium recovery and estimation in some certified reference materials and environmental samples.