Study on the Ytterbium(III) Extraction and Stripping Performance of Cyanex923 in Nitric Acid Medium

In the present work,the extraction performance for the rare earth element Yb(Ⅲ) of a kind of neutral extractant named Cyanex923,a mixture of straight chain triakylphosphine oxide had been investigated.The effects of oscillation time,Yb(Ⅲ),Cyanex923 and NO-3 concentration on Yb(Ⅲ) extraction were studied,respestively.The extraction mechanism was suggested based on the slope analysis and the extraction equilibrium equation was obtained.Then,the effect of temperature on Yb(Ⅲ) extraction was studied.From the temperature dependent data,values of the thermodynamic parameters(ΔH,ΔS and ΔG) were calculated by van′t Hoff equation during temperature range of 298~323 K and the thermodynamic properties were discussed.Positive ΔH indicated the reaction belonged to endothermic reaction,positive ΔS indicated the reaction was achieved ensily.The stripping behavior of loaded Cyanex923 was investigated by different concentration of nitric acid.The stripping rate reached 100% when the concentration of nitric acid was above 1.2 mol·L-1.The result showed that the loaded Cyanex923 was easy to be stripped for recycle.