본 연구는 Np의 환원제로 H₂O₂가 함유된 IM 이하의 저산도 질산용액으로부터 DEHPA(di-(2-ethyhexyl)phosphoric acid) 추출제에 의한 Np의 추출 및 역추출 조건 설정과 추출속도 향상에 주안점을 두어, 회분식으로 실험을 수행하였다. 저산도 질산용액에서 Np의 산화상태는 주로 Np(V)로 존재하고 있음을 확인하였으며, NP의 추출율은 H₂0₂농도 및 DEHPA의 농도 증가에 따라 증가하고, 질산농도 증가에 따라 급격히 감소하였다. 제3의 산화/환원제가 첨가되지 않는 경우 추출율은 약 70% 정도로 다소 낮지만, DEHPA에 의해 추출이 가능함을 보았다. 또한 추출속도는 H₂O₂농도의 0.516 승에 비례하며, 질산농도의 0.483 승에 반비례하고 있는 다음과 같은 식을 얻었다. d[Np(V)]/dt=-1.391×10^(-2)[H₂O₂]^(0.516)[HNO₃]^(-0.483) [Np(V)] 그리고 과산화수소의 첨가 유무에 관계없이, 유기상으로 추출된 Np은 옥살산(oxalic acid)에 의해 효과적으로 역추출되었으며, 0.5M 옥살산으로 약 92% 이상을 역추출하였다.

Extraction behaviour of Np with DEHPA(di-(2-ethyhexyl) phosphoric acid) from the low nitric acid solution(below 1M HNO₃) containing H₂O₂as a reducing agent was studied at a batch system in order to establish the conditions of extraction and stripping and to enhance the extraction rate. As results, it was confirmed that the Np was mainly the pentavalent oxidation state in the low nitric acid solution. The extraction yield of Np was increased with increasing the concentration of DEHPA and H₂O₂and decreased more rapidly with the increase of HNO₃ concentration. It was also found that the Np could be extracted into DEHPA even without the addition any redox agents, although the extraction yield is rather low as about 70%. The extraction rate was proportional to the 0.516 power of H₂O₂concentration and inversely proportional to 0.483 power of HNO, concentration as follows. d[Np(V)]/dt=-1.391×10^(-2)[H₂O₂]^(0.516)[HNO₃]^(-0.483) [Np(V)] Regardless of the H₂O₂, the Np extracted in the organic phase was effectively stripped to the aqueous phase with H₂C₂O₄. The Np could be stripped more than 92% with 0.5M H₂C₂O₄.