基于碳酸盐环境的甲基三辛基碳酸铵萃取铀的分配比模型

In this study, a distribution ratio model for extraction of uranium by methyltrioctylammonium carbonate was established to address the issue of difficult process design in the extraction process of alkaline spent nuclear fuel reprocessing based on carbonate system, namely the CARBEX process. The effects of carbonate and uranium concentrations in the aqueous phase, extractant concentration, and phase volume ratio were mainly investigated. Based on the extraction equilibrium equation of UO₂(O₂) (CO₃)⁴₂^- extracted by methyltrioctylammonium carbonate in a carbonate system, a distribution ratio model of uranium was established by segmental fitting using the method of separating variables. The results revealed that compared with the experimental value, the relative error of the model is within ±10%. However, some data deviations are too large. The analysis shows that the model is appropriate when the uranium concentration in the organic phase reaches half of the extractant concentration before extraction. However, when the concentration exceeds half, the chemical form of uranium will change in the organic phase, and the model will no longer be applicable.