본 연구는 30% TBP/n-dodecane에 CMPO[n-octyl(phenyl)-N,N-diisobutyl carbamoyl methyl phosphine oxide]를 소량 첨가하는 방법(30% TBP/xM CMPO)에 의해 방사성폐액으로부터 Tc의 추출률을 증진시키면서 Tc, Np, U만을 선택적으로 공추출시키는 조건을 찾기 위하여 수행하였다. 30% TBP/xM CMPO에 의한 Tc 추출의 경우 질산농도 0.8 M 이하에서는 H(+) 이온 농도와 TBP/CMPO의 자유농도 간의 경쟁반응으로, 1 M 이상에서는 TBP/CMPO의 자유농도에만 의존하여 추출된다. 반면에 30% TBP/0.02 M CMPO에 U이 첨가될 경우 유기상 내 함유되어 있는 U과 수용상 내 TcO4-이 착물을 형성하여 추출되는 NO3- 이온 교환반응에 의해 추출된다. 한편 질산농도 1 M에서 Np의 산화제로는 K2Cr2O7이 효과적이다. 1 M HNO3 (0.001 M K2Cr2O7 첨가) 및 30% TBP/0.02 M CMPO에서 Tc, Np, U의 추출률은 각각 66.4%, 85.7%, 94.7%로 Tc의 추출 증진은 물론 Np과 U의 추출 또한 증진시킨다. 이때 Am, Nd, Mo, Fe 등은 각각 10.1%, 11.1%, 11.5%, 5.1%, 2%가 추출되어 Tc, Np, U만을 선택적으로 추출하려는 본 연구 목적을 만족시키고 있다. 연속추출 장치 운전 시 O/A 비는 1 정도에서 조업함이 효율적이다. 그리고 30% TBP/xM CMPO 사용 시 제3상 형성 방지를 위해 Zr의 선 제거가 필요하다.

In other to enhance extraction yield of Tc, the extraction of Tc(TcO4-) in a simulated solution by means of adding a small amount of n-octyl(phenyl)-N,N-diisobutyl carbamoyl methyl phosphine oxide(CMPO) in the 30% tributyl phosphate/ n-dodecane(hereafter described 30% TBP/xM CMPO) was investigated, and effects of nitric acid and CMPO concentration for the selective_x000D_ co-extraction of Tc, Np and U were studied. The extraction of Tc(DTc-TBP/CMPO) with 30% TBP/xM CMPO was occurred by competing reaction between H+ ion concentration in aqueous phase and free TBP and CMPO concentration at less than 0.8M HNO3. Above 1 M HNO3, however, DTc-TBP/CMPO depended on only the free TBP and CMPO concentration. In the presence of U, the extraction of Tc(DTc-U-TBP/CMPO) with 30% TBP/0.02M CMPO occurred by a NO3- ion exchange mechanism through complex formation of TcO4- and U in organic phase. K2Cr2O7 was an effective oxidant of Np at 1 M HNO3. At 1 M HNO3, 0.001 M K2Cr2O7 and 30%_x000D_ TBP/0.02 M CMPO, extraction yields of Tc, Np and U were 66.4%, 85.7%, 94.7%, respectively, and those of Am, Eu, Nd, Mo and Fe were 10.1%, 11.1%, 11.5%, 5.1%, 2%, respectively. It was found that the system of 30% TBP/xM CMPO was enhanced the extraction yield of Np, U as well as Tc, and the selective co-extraction of Tc, Np and U from the radwaste solution was satisfied. For the continuous operation by using a mixer settler type extractor, O/A=1 was more effective condition. When the 30% TBP/xM CMPO system was used, Zr had to be pre-removed to prevent the formation of 3rd phase.

Tc Np U TBP CMPO Solvent Extraction

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