Investigations on the use of commercial phosphonic acid derivative for the extraction and separation of Zr(IV) and Nb(V) from their admixture in nitric acid solution

Abstract

The extraction of 1.09 × 10−2 Zr(IV) and 1.07 × 10−3 Nb(V) from their admixture solution was done using a phosphonic acid derivative (Ionquest 801 = IQ-801/kerosene). The calculated extraction constants for Zr(IV) and Nb(V) were found to be 17.1 × 103 M−3 and 1.1 × 103 M−1, respectively. The suggested extraction conditions were found to be (time =15–30 min, Organic: Aqueous ratio = 1, [HNO3] = 3 M, [IQ-801] = 0.015–0.02, and T = 25 ± 1. The calculated loading capacities per mole of IQ-801 were found to be 0.8 moles of Zr(IV) and 9 × 10−2 moles of Nb(V). According to McCabe-Thiele diagrams, 0.02 M IQ-801 can completely extract 1 × 10−2 M Zr(IV) and 1 × 10−3 M Nb(V) in just 2 stages. In the stripping process, about 99% Zr(IV) was stripped by stripping precipitation with 0.1 M oxalic acid and 1 M NaF, which also provides the best conditions for the separation of Nb(V) from Zr(IV). The highest separation was obtained using citric acid concentrations ranging from 0.25 to 4 M, oxalic acid concentrations ranging from 0.05 to 1 M, and sulfuric acid concentrations ranging from 1.5 to 3 M. A flow chart outlining the proposed technique steps for separating Zr(IV) and Nb(V) from an HNO3 solution using IQ-801 was suggested.