Extraction and Stripping Behaviors of 14 Lanthanides from Nitric Acid Medium by N,N’-dimethyl-N,N’-dioctyl Diglycolamide

N,N’ -dimethyl- N,N’ -dioctyl diglycolamide (DMDODGA) in 40/60 (V/V)% 1-octanol/kerosene was used to extract 14 lanthanides from nitric acid solution. The effects of the aqueous acidity, the DMDODGA concentration, and the temperature on the distribution ratio of Ln(III) were investigated. The extraction equilibrium constants K and the thermodynamic parameters were determined by the slope analysis method combined with Pitzer model. The IR spectra of the extracted species and pure extractant were recorded and analyzed. Moreover, 0.001 mol/L nitric acid is the suitable stripping agent, and the stripping efficiency of all lanthanides can reach up 90% by three times of stripping.