[en] The Federal Energy Regulatory Commission (FERC) recently set for hearing a complaint brought against Carolina Power ampersand Light Company (CP ampersand L) by certain of its wholesale customers. Among the issues to be heard is the prudence of CP ampersand L management in operating two of the company's nuclear power plants, each of which had been the subject of service outages. The wholesale customers contended that those outages could have been avoided had CP ampersand L acted prudently; CP ampersand L disagreed. (Re North Carolina Membership Corp. and Brunswick Electric Membership Corp. V. Carolina Power ampersand Light, FERC Docket Nos. EL91-28-000 and EL91-54-000, open-quotes Order Granting Interventions...close quotes 57 FERC). This article examines the appropriateness of FERC holding hearings on a utility's prudence in operating a nuclear plant. The author believes that not only should FERC hold such hearings, but that it also has a duty to make prudence decisions

[en] 'The authors have begun to examine the extraction and recovery of heavy elements from aqueous waste streams using redox-active metal chalcogenides. They have been able to prepare extractants from known chalcogenide starting materials, studied the efficacy of the extractants for selective removal of soft metal ions from aqueous phases, studied the deactivation of extractants and the concomitant recovery of soft metal ions from the extractants, and characterized all of the solids and solutions thus far in the study. The study was proposed as two parallel tasks: Part 1 and Part 2 emphasize the study and development of known metal chalcogenide extractants and the synthesis and development of new metal chalcogenide extractants, respectively. The two tasks were divided into sub-sections that study the extractants and their chemistry as detailed below: Preparation and reactivity of metal chalcogenide host solids Extraction of target waste (guest) ions from simulated waste streams Examination of the guest-host solids recovery of the guest metal and reuse of extractant Each section of the two tasks was divided into focused subsections that detail the specific problems and solutions to those problems that were proposed. The extent to which those tasks have been accomplished and the continued efforts of the team are described in detail below. (b) Progress and Results. The DOE-supported research has proceeded largely as proposed and has been productive in its first 12 months. Two full-paper manuscripts were submitted and are currently under peer review. A third paper is in preparation and will be submitted shortly. In addition, 5 submitted or invited presentations have been made.'

[en] 'Mercury and other highly-toxic heavy metals such as cadmium and lead are present in many aquatic environments, and the remediation of such environments or the avoidance of heavy-metal contamination in the first place is an area of active interest. In recent years tougher environmental regulations and the high initial cost of new, more effective, and more selective extractants has made the reuse of extractant materials and the minimization of secondary waste volume a focus of their scientific effort. The authors research has involved the investigation of redox-active layered metal chalcogenides as selective, effective, and redox-recyclable extractants for heavy metals from aqueous solution.'

[en] The authors evaluated several calorimetric assays for ReO₄^-, and discovered that all were flawed. They evaluated atomic absorption spectroscopy as a technique to determine sub-millimolar concentrations of ReO₄^-, and discovered that it is not sensitive enough for their use. However, they discovered that ICP-AES can be used to determine concentrations of ReO₄^- down to 0.25 ppm. They next determined that ReO₄^- can be quickly extracted (10 minutes or less) from aqueous HNO₃ using the commercial extractant Aliquat-336 nitrate diluted with 1,3-diisopropylbenzene. Higher concentrations of extractant led to higher values of K_d (the distribution ratio). K_d was lower as the nitrate concentration of the medium increased, and was also lowered by increasing the acidity at constant nitrate ion concentration. The authors performed parallel studies with TcO₄^-, determining that K_d(ReO₄^-) and K_d(TcO₄^-) track similarly as the conditions are changed. An effort was made to prepare substituted pyridium nitrate salts that are soluble in organic solvents to be used as alternate extractants. However, in all cases but one, the salts were also soluble to some extent in the aqueous phase, significantly limiting their usefulness as extractants for these purposes. Many of the new extractant salts would partition between the organic solvent and water so that 10% of the extractant salt was in the aqueous phase. Only 1-methyl-3,5-didodecylpyridium nitrate did not show any measurable solubility in water. However, this compound was not as good an extractant as Aliquat-336. A considerable effort was also made to find suitable alternative solvents to 1,3-diisopropylbenzene. Several ketone solvents with flash points above 60 C were tested, and two of these, 2-nonanone and 3-nonanone, were superior to 1,3-diisopropylbenzene as a diluent

[en] The author studied liquid anion exchangers, such as Aliquat-336 nitrate, various pyridinium nitrates, and related salts, so that they may be applied toward a specific process for extracting (partitioning) and recovering ⁹⁹TcO₄^- from nuclear waste streams. Many of the waste streams are caustic and contain a variety of other ions. For this reason, the author studied waste stream simulants that are caustic and contain appropriate concentrations of selected, relevant ions. Methods of measuring the performance of the exchangers and extractant systems included contact experiments. Batch contact experiments were used to determine the forward and reverse extraction parameters as a function of temperature, contact time, phase ratio, concentration, solvent (diluent), and other physical properties. They were also used for stability and competition studies. Specifically, the author investigated the solvent extraction behavior of salts of perrhenate (ReO₄^-), a stable (non-radioactive) chemical surrogate for ⁹⁹TcO₄^-. Results are discussed for alternate organic solvents; metalloporphyrins, ferrocenes, and N-cetyl pyridium nitrate as alternate extractant salts; electroactive polymers; and recovery of ReO₄^- and TcO₄^-

[en] Salts of the OTeF₅^- anion were investigated by ir and Raman spectroscopy and by x-ray crystallography. Experimental results were compared with ab initio Hartree-Fock calculations on the OTeF₅ radical, Na⁺OTeF₅^-, and the singlet and triplet states of the free OTeF₅^-. The compound [(PS)H⁺][OTeF₅^-] was examined by single-crystal X-ray crystallography ((PS)H⁺ = protonated 1,8-bis(dimethylamino)naphthalene): bar P1, a = 8.241 (1) angstrom, b = 8.768 (2) angstrom, c = 12.591 (3) angstrom, α = 74.08 (2)degree, β = 78.00 (2)degree, γ = 80.23 (2)degree, Z = 2, T = -106 degree C. Unlike other salts of the OTeF₅^- anion, [(PS)H⁺][OTeF₅^-] did not exhibit any O/F disorder. Since the spectroscopic data for [(PS)H⁺][OTeF₅^-] closely matched those of [N(n-Bu)₄⁺][OTeF₅^-], it was concluded that this structure contains the best approximation of the structure of the free OTeF₅^- anion. The librationally corrected results are Te-O = 1.803 angstrom, Te-F_ax = 1.872 angstrom, Te-F_eq = 1.870 angstrom (average), and O-Te-F_eq = 95.2 degrees (average). A normal-coordinate analysis of OTeF₅^- was carried out by using this geometry and spectroscopic data for the ¹⁶O and ¹⁸O equivalents of [N(n-Bu)₄⁺][OteF₅^-]. 41 references, 5 figures, 8 tables

[en] Metal ion extraction using hydrophobic anions has been investigated by several researchers for remediation of Cs-137 and Sr-90 in nuclear waste. The rich derivative chemistry of the cobalt bis-dicarbollide anion makes it amendable to systematic studies of the relative importance of anion structure, solvent, and synergists on the extraction selectivity and efficiency. Halogenation or alkylation of cobalt dicarbollide strongly influences the anion's solubility and stability but has little effect on extraction properties. Alkali metal selectivity depends primarily on solvent, while alkaline earth selectivity is driven by the concentration and molecular weight of polyethylene glycol synergists. Additional aspects of ligand design, including a simple extraction and recovery cycle based on redox-active metal centers, will be discussed

[en] We are investigating a new paradigm in separation science, the use of recyclable, redox-active metal-complex extractants for the removal and isolation of ionic contaminants from acidic, neutral, or alkaline aqueous solutions. In this paper, we report a novel process for the extraction and recovery of TcO₄^-. The noteworthy features of the process are that (i) technetium is recovered as a solid of minimal volume, (ii) the extractant and the organic solvent are recovered unchanged and can be reused many times, and (iii) the expendable chemicals are readily available, inexpensive, easy to handle, and relatively nontoxic. The key element of the process is a lipophilic, redox-active, metal-complex anion extractant, 1,1',3,3'-tetrakis(2-methyl-2-hexyl)ferrocene, 1. 21 refs., 1 fig., 3 tabs

[en] We are investigating a new strategy for liquid-liquid extraction and recovery of Cs-137 and Sr-90 from aqueous nuclear waste and contaminated groundwater. The extractants are hydrophobic, redox-active derivatives of Ni(C₂B₉H₁₁) and FeCp(C₂B₉H₁₁). They are activated for extraction by reduction to the corresponding monoanions. The cesium and strontium cations are recovered from the organic phase by reoxidation (deactivation) of the anionic extractants back to the neutral species, which also allows for recovery and reuse (i.e., recycling) of the extractants. The reduction potentials of the parent compounds are 0.18 V and -0.08V respectively (acetonitrile, SCE). Therefore, the derivatives can be easily reduced and re-oxidized by many common substances. The redox potentials, relative solubilities in organic solvents and aqueous solution, and D values for extraction and recovery, which vary as a function of substituent groups on the ligands, will be discussed

[en] Two new redox-active organometallic extractants for the redox-recyclable extraction and recovery (R²ER) of the cationic radionuclides ¹³⁷Cs⁺ and ⁹⁰Sr²⁺ from aqueous waste simulants, Na[Fe(η⁵-C₅H₅)(η⁵-(3)-1,2-C₂B₉H₉(n-C₁₂H₂₅)₂)] (Na⁺I^-) and Na[Fe(η⁵-C₅H₅)(η⁵-(3)-1,2-C₂O₉H₇(n-C₁₂H₂₅)₂-9,12-Br₂)] (Na⁺ II^-), were synthesized and investigated. When diluted with toluene or xylenes, they extracted Cs⁺ from aqueous waste simulants such as (1) 1 mol L^-1 NaOH + 1 mol L^-1 NaNO₃, (2) 1 mol L^-1 HNO₃, and/or (3) 1 mol L^-1 NaCl, with D(Cs) values that ranged from 5 to 20; the corresponding D(Sr) values were ≤ 0.04. The addition of poly(ethylene glycol) as a co-diluent increased D(Sr) values to as high as 33 but decreased D(Cs) values by a factor of 2--10, depending on conditions. When separated from the raffinate and exposed to air, the extractant-containing organic phase released > 88% of its radioactivity in the form of a solid precipitate of minimal volume. When a small amount of water was present during this procedure, the extractant-containing organic phase released ≥ 99% of its radioactivity to the new aqueous phase. When an oxidized dilute extractant was rereduced and used for a second R²ER cycle, the D(Cs) value was unchanged