LEAD(II) EXTRACTION FROM NITRATE SOLUTIONS WITH DI(2-ETHYLHEXYL)PHOSPHORIC ACID

In this paper, equilibrium studies were carried out on the extraction of trace amounts oflead(II) from 0.2 mol/dm(3) (Na,H)NO3 aqueous solut ions with di(2-ethylhexyl)phosphoric acid (HR) dissolved in n-dodecane at 298 K. The composition of the extracted species was numerically fo und to be PbR(2)(HR) and PbR(2)(HR)(2). A chemical equilibrium model w as developed to evaluate the thermodynamic constants for the formation of the two complexes, based on the law of mass action, which took int o account the activity corrections of reactive species in the aqueous phase by employing the Bromley and the simplified Fitter equations and those of the extractant in the organic phase.