Stoichiometric study of phosphovanadomolybdate complex and its use to determine effect of uranium extraction by DEHPA/TOPO on the concentration of phosphoric acid using spectrophotometric method

A simple spectrophotometric method was used for the determination of phosphorus concentration in Syrian commercial phosphoric acid during uranium recovery process using DEPHA/TOPO. The absorbance of yellow phosphovanadomolybdate complex was measured at 320 nm wavelength. The most stable stoichiometric (P:V:Mo) analytical complex in the formed phosphovanadomolybdate compound was studied by spectrophotometric method at PH1. This study showed that the molar ratios (1:1:25) of (P:V:Mo) were the critical ratio which gives very pure analytical signal far from the noise region. The present study found that the extraction mixture (DEHPA/TOPO) extracts 9% of P2O5 to the organic phase during the recovery process of uranium from commercial phosphoric acid . This was also confirmed using radioactive tracer (32P). Accuracy, precision, and detection limit of the present method are 105%, 0.551μg P ml-1, and 0.06μg P ml-1 respectively. The results correlate significantly with the results of the standardized quenolene gravimetric method, and the present method saves time and chemicals. (author)