Non-Dispersive Solvent Extraction of Uranium from Nitric Acid Medium by Several Amides and their Mixture with TODGA using a Hollow Fiber Contactor

Non-dispersive solvent extraction (NDSX) of uranium from nitric acid feed solutions was studied using three dialkyl amides, viz. N,N-di-n-hexylhexanamide (DHHA), N,N-di-n-hexyloctanamide (DHOA), N,N-di-n-hexyldecanamide (DHDA), and their binary mixtures with TODGA (N,N,N’,N’-tetra-n-octyldiglycolamide) in normal paraffinic hydrocarbon (NPH) as the carrier solvents. The feed solution usually contained 10.6 g/L of uranium in 3 M HNO3 and the extraction studies were carried out using a commercial hollow fiber contactor operating in recirculation mode at a flow rate of 3 L/h. In a separate set of experiments, the stripping studies were carried out in the NDSX mode using the U loaded organic extract and 0.01 M HNO3 or 1 M Na2CO3 as the strippant. Use of TODGA along with the amides resulted in faster mass transfer rates though the extraction and stripping efficiencies of the dialkylamides were reversed in the mixture as compared to that observed in the absence of TODGA.