The Extraction of Metal Contaminants using Supercritical CO₂

Abstract

Conventional decontamination methods utilize water-based systems, which generate high amounts of secondary wastes. Herein, we describe an environmentally benign decontamination method using liquid and supercritical CO2. The use of CO2 as a solvent affords effective waste reduction by its ability to be recycled, thereby leaving be hind only the contaminants upon its evaporation. In this study, a CO2 solution process was assessed using t-salen(t-butylsalen), DC18C6 (dicyclohexano-18Crown6), 8-HQN(8-hydroxyquinoline), NEt4PFOSA(perfluoro-1-octanesulfonic acid tetra-ethyl ammonium salt), and NEt4PFOA(pentadecafluorooctanoic acid ammonium salt) to extract spiked radioactive contaminants(Nb,Zr,Co,Sr) from an inert sample matrix, namely filter paper. With the static extraction method, Sr was extracted with a maximum extraction rate of 97%, and Nb was extracted with a maximum extraction rate of 75%. Additionally, we were also able to extract Co and Zr with maximum extract ion ratesof 73% and 64%, respectively. ■ keyword :|Decontamination|Nuclear|Extraction|Supercritical Fluid|Carbon Dioxide|