Spectrophotometric studies on chelating behavior of oxalohydroxamic acid with uranium in aqueous streams

Abstract

Study of the complex formation of oxalohydroxamic acid (OHA) with uranium is investigated by spectrophotometry. Oxalohydroxamic acid forms orange-yellow complex with uranium(VI) in aqueous medium and shows maximum absorbance at 381 nm at pH 6.2. The stoichiometry of the coloured species is determined to be 1:5 ratios (uranium-oxalohydroxamic acid). A calibration graph is made for the concentration range of uranium from 10-100 mg/L. The molar absorption coefficient at 381nm, detection limit and Sendell’s sensitivity are 2230 LMol^-1cm^-1, 11 mg/L and 0.11 µg/cm² respectively. Relative standard deviation is less than 2% and correlation coefficient is 0.998. In these studies, oxalohydroxamic acid complex with uranium, effect of reagent-metal ratio, pH and reagent stabilities are investigated. The results obtained by the proposed procedure are in good agreement with those obtained by the standard procedure. The advantage of the present study is that, it does not generate analytical waste because hydroxamic acids are composed of only C, H, N and O atoms they can be decomposed to gases so that their application in industrial processes will not lead to increase in waste volume. The method is also applicable for the determination of concentration of uranium in reprocessing samples.

Keywords: Uranium, Oxalohydroxamic acid, Spectrophotometry, pH, Molar absorptivity