Studies on avoiding second organic phase in DHDECMP-TBP/kerosene with the extraction of HNO3-Gd

The bidentate extractant of DHDECMP (CMP) may by more practical in the treatment of high-level liquid waste (HLLW) if it could be diluted by kerosene. Bu it is difficult to avoid the formation of second organic phase in CMP/kerosene with the extraction of HNO3 and RE. It is advantageous to avoid the formation of second organic phase after the extraction of HNO3 and Gd by adding TBP. The formation conditions of second organic phase are studied and the loaded capacity of RE-HNO3 is measured. The results are as follows. Raising temperature has a slight advantage to avoid formation of second organic phase. The addition of TBP is beneficial to avoid second organic phase. An organic system of 0.60 mol/L CMP-1.20 mol/L TBP/kerosene contacting with an aqueous solution containing 6.0 mol/L HNO3 does not appear second organic phase. The extraction of RE leads to form second organic phase which does not occur when it only extracts HNO3. It is able to avoid second organic phase with a low concentration of CMP. The higher concentration of CMP, the higher loaded capacity of Gd3+ and HNO3. It is advantageous to avoid second organic phase formation and also to get a higher loaded capacity of Gd3+ and HNO3 with increasing concentration of TBP. The loaded capacity of Gd decreases with an increasing initial concentration of HNO3 in aqueous phase because of an increasing concentration of HNO3 in the organic phase. The loaded capacity of Gd increases with raising temperature. To treat HLLW, the organic system containing 0.60 mol/L CMP and 1.40 mol/L TBP is recommended