Mercury extraction by the TRUEX process solvent: I. Kinetics, extractable species, dependence on nitric acid concentration and stoichiometry
Mercury extraction from acidic aqueous solutions by the TRUEX process solvent (0.2 M CMPO, 1.4 M TBP in n-dodecane) has not extensively been examined. Research at the Idaho Chemical Processing Plant is currently in progress to evaluate the TRUEX process for actinide removal from several acidic waste streams, including liquid sodium-bearing waste (SBW), which contains significant quantities of mercury. Preliminary experiments were performed involving the extraction of Hg{sup 203}, added as HgCl{sub 2}, from 0.01 to 10 M HNO{sub 3} solutions. Mercury distribution coefficients (D{sub Hg}) range between 3 and 60 from 0.01 M to 2 M HNO{sub 3}. At higher nitric acid concentrations, i.e. 5 M HNO{sub 3} or greater, D{sub Hg} significantly decreases to values less than 1. These results indicate mercury is extracted from acidic solutions {<=}{approximately}2 M HNO{sub 3} and stripped with nitric acid solutions {>=}{approximately}5 M HNO{sub 3}. Experimental results indicate the extractable species is HgCl{sub 2} from nitrate media, i.e., chloride must be present in the nitrate feed to extract mercury. Extractions from Hg(NO{sub 3}){sub 2} solutions indicated substantially reduced distribution ratios, typically D{sub Hg}< 1, for the range of nitric acid concentrations examined (0.01 to 8 M HNO{sub 3}). Extraction of mercury, as HgCl{sub 2}, by the individual components of the TRUEX solvent was also examined from 2 M HNO{sub 3}. The diluent, n-dodecane, does not measurably extract mercury. With a 1.4 M TBP/n-dodecane solvent, D{sub Hg} {approximately}3.4 compared with D{sub Hg} {approximately}7 for the TRUEX solvent. Classical slope analysis techniques were utilized to evaluate the stoichiometric coefficients of Hg extraction independently for both CMPO and TBP.
- Research Organization:
- EG and G Idaho, Inc., Idaho Falls, ID (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG07-81ID12345
- OSTI ID:
- 135100
- Report Number(s):
- INEL-95/00241; CONF-9505164-1; ON: DE96002524; TRN: 96:001242
- Resource Relation:
- Conference: Conference on challenges and innovations in the management of hazardous waste, Washington, DC (United States), 10-12 May 1995; Other Information: PBD: 1995
- Country of Publication:
- United States
- Language:
- English
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