A new tri-n-butylphosphate−nitric acid (TBP−HNO 3 ) adduct was prepared by combining TBP and fuming (90%) HNO 3 . The adduct was characterized, and its phase-equilibrium behavior in supercritical carbon dioxide is reported. Supercritical carbon dioxide (sc-CO 2 ) was modified with this new adduct [TBP(HNO 3 ) 5.2 (H 2 O) 1.7 ], and the extraction efficacies of selected rare earth oxides (Y, Ce, Eu, Tb, and Dy) at 338 K and 34.5 MPa were compared with those obtained using an adduct formed from concentrated (70%) HNO 3 and TBP [TBP(HNO 3 ) 1.7 (H 2 O) 0.6 ]. All rare earth oxides tested with both adduct species could be extracted with the exception of cerium oxide. The water and acid concentrations in the different adducts were found to play a significant role in rare earth oxide extraction efficiency.
Absolute rate constants for the free-radical-induced degradation of trichloronitromethane (TCNM, chloropicrin) were determined using electron pulse radiolysis and transient absorption spectroscopy. Rate constants for hydroxyl radical, *OH, and hydrated electron, e(aq)-, reactions were (4.97 +/- 0.28) x 10(7) M(-1) s(-1) and (2.13 +/- 0.03) x 10(10) M(-1) s(-1), respectively. It appears that the *OH adds to the nitro-group, while the e(aq)- reacts via dissociative electron attachment to give two carbon centered radicals. The mechanisms of these free radical reactions with TCNM were investigated, using 60Co gamma irradiation at various absorbed doses, measuring the disappearance of TCNM and the appearance of the product nitrate and chloride ions. The rate constants and mechanistic data were combined in a kinetic computer model that was used to describe the major free radical pathways for the destruction of TCNM in solution. These data are applicable to other advanced oxidation/reduction processes.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.