Hélène Rouquette

Calixarenes with diphenylphosphoryl acetamide functions at the upper rim. A new class of highly efficient extractants for lanthanides and actinides

Various calix[4]arene tetraalkyl ethers and a calix[5]arene pentaalkyl ether substituted at the upper rim by the CMPO-like functional group –NH–C(O)–CH2–P(O)Ph2 as well as some linear model compounds have been synthesized for the first time. Their ability to extract europium, thorium, neptunium, plutonium and americium from 1 mol dm–3 aqueous HNO3 into methylene chloride or o-nitrophenyl hexyl ether was studied under various conditions. All the new oligomeric ligands, but especially the calixarene derivatives, are tremendously strong extractants compared with the commonly used CMPO [(N,N-diisobutylcarbamoylmethyl)octylphenylphosphine oxide]. Also in transport studies through supported liquid membranes their efficiency is higher than that of CMPO which shows lower transport rates even at a 10-fold concentration.

Cobalt bis(dicarbollide) ions with covalently bonded CMPO groups as selective extraction agents for lanthanide and actinide cations from highly acidic nuclear waste solutions

A new series of boron substituted cobalt bis(dicarbollide)(1−) ion (1) derivatives of the general formula [(8-CMPO-(CH2-CH2O)2-1,2-C2B9H10)(1′,2′-C2B9H11)-3,3′-Co]− (CMPO = Ph2P(O)-CH2C(O)NR, R = C4H9 (3b), -C12H25 (4b), -CH2-C6H5 (5b)) was prepared by ring cleavage of the 8-dioxane-cobalt bis(dicarbollide) (2) bi-polar compound by the respective primary amines and by subsequent reaction of the resulting amino derivatives (3a–5a) with the nitrophenyl ester of diphenylphosphorylacetic acid. The compounds were synthesized with the aim to develop a new class of more efficient extraction agents for liquid–liquid extraction of polyvalent cations, i.e. lanthanides and actinides, from high-level activity nuclear waste. All compounds were characterized by a combination of 11B NMR, 1H high field NMR, Mass Spectrometry with Electrospray and MALDI TOF ionisation, HPLC and other techniques. The molecular structure of the supramolecular Ln3+ complex of the anion 5b was determined by single crystal X-ray diffraction analysis. Crystallographic results proved that the Ln(III) atom is bonded to three functionalised cobalt bis(dicarbollide) anions in a charge compensated complex. The cation is tightly coordinated by six oxygen atoms of the CMPO terminal groups (two of each ligand) and by three water molecules completing the metal coordination number to 9. Atoms occupying the primary coordination sphere form a tri-capped trigonal prismatic arrangement. Very high liquid–liquid extraction efficiency of all anionic species was observed. Moreover, less polar toluene can be applied as an auxiliary solvent replacing the less environmentally friendly nitro- and chlorinated solvents used in the current dicarbollide liquid–liquid extraction process. The extraction coefficients are sufficiently high for possible technological applications.

A solution for cesium removal from high-salinity acidic or alkaline liquid waste: The crown calix[4]arenes

ABSTRACT The scientific literature abounds with articles on the extraction of cesium from liquid waste. From the 1940s, several classes of inorganic exchangers were used for cesium removal, such as zeolites, hexacyanoferrates, zirconium phosphate, ammonium phosphomolybdate, and, more recently, crystalline silicotitanate. Later, organic compounds like formophenolic resins, tetraphenylboron, or extractants such as dicarbollides or crown ethers were proposed. Generally, these compounds were only able to efficiently remove cesium under restrictive conditions (alkaline medium, low salinity, etc.) The performances of most of these compounds strongly decreased as the acidity (or salinity) of the liquid waste increased. Artifices had to be implemented to improve the performances of extractants. A restricted number of inorganic exchangers allowed the cesium removal, but often they could not be eluted or needed prohibitive volumes of saline eluent, leading to large volumes of secondary waste. Calix[4]arenes monocro...

C-substituted bis(dicarbollide) metal compounds as sensors and extractants of radionuclides from nuclear wastes

Abstract [3,3′-M(1,2-C 2 B 9 H 11 ) 2 ] − (M=Co 3+ , Fe 3+ , Ni 3+ ) compounds have been implemented in PVC membranes to study their performance as Cs + sensors in ion selective electrodes. They show a near-Nernstian response close to 51 mV (decade) −1 . The three display a similar behaviour, and the [3,3′-Co(1,2-C 2 B 9 H 11 ) 2 ] − anion was chosen as the parent chemical on which C-substitution, both alkyl or aromatic, were done. The species [3,3′-Co(1-CH 3 -2-(CH 2 ) n OR-1,2-C 2 B 9 H 9 ) 2 ] − ([ 4 ] − : n =3, R=–CH 2 CH 3 ; [ 5 ] − : n =3, R=–(CH 2 ) 2 OCH 3 ; [ 6 ] − : n =3, R=–(CH 2 ) 3 CH 3 ; [ 7 ] − : n =6, R=–(CH 2 ) 3 CH 3 ), and [3,3′-Co(1-C 6 H 5 -1,2-C 2 B 9 H 10 ) 2 ] − ([ 8 ] − ) and [3,3′-Co(1,7-(C 6 H 5 ) 2 -1,7-C 2 B 9 H 9 ) 2 ] − ([ 9 ] − ) were tested for 137 Cs, 90 Sr and 152 Eu in extraction. Permeability tests on supported liquid membranes with H[ 6 ], H[ 7 ] and H[ 9 ] have shown that these compounds present the highest values reported so far for this sort of radionuclide transport experiments. The structure of the carrier [N((CH 2 ) 3 CH 3 ) 4 ][ 9 ] is reported. Crystals were monoclinic, space group P 2 1 / c (no.14), a =18.255(4) A, b =15.871(9) A, c =18.684(14) A, β =105.64(3)°, V =5213(5) A 3 and Z =4. The carbons apart structure may be one of the reasons of the excellent performance of this compound in Cs + transport in SLM with nitrophenylhexyl ether as a solvent.

Calix[4]arenes with CMPO functions at the narrow rim. Synthesis and extraction properties

The synthesis of three new derivatives of tert-butylcalix[4]arene bearing four carbamoylmethylphosphine oxide (CMPO) groups as ligating functions on the narrow rim is described. These are easily prepared in 65–80% yield via acylation of the corresponding fixed cone aminoalkoxy (C2 to C4) derivatives with p-nitrophenyl (diphenylphosphoryl)acetate. Extraction studies of selected lanthanides (La3+, Eu3+, Yb3+) and thorium (Th4+) from 1 M HNO3 to CH2Cl2 show a strong increase of the percentage extracted (%E) with increasing length of the spacer. Extraction of Am3+, La3+, Nd3+, Sm3+ and Eu3+ from (0.1–4) M HNO3 into o-nitrophenyl hexyl ether shows, in contrast to the wide rim CMPO derivative, no decrease of the distribution coefficient for higher concentrations of nitric acid.

New Calix[4]arene-monobenzo- and -dibenzo-crown-6 as Cesium Selective Ionophores in the Radioactive Waste Treatment: Synthesis, Complexation and Extraction Properties

Cesium possesses two long lived isotopes 135Cs and 137Cs and the first one has a very long (2.3 × 106 y) half life and is one of the most mobile nuclides in a repository.Calix[4]arene-crowns-6 in the 1,3-alternate conformation areemerging as a new class of ionophores exhibiting a very high efficiency and selectivity in the complexation of cesium ion and itsremoval from highly acidic ([HNO3] = 3–4 M) radioactive waste having also high sodium nitrate concentration ([NaNO3] = 2–4 M). In order to improve both efficiency and cesium selectivity we have synthesised the novel calix[4]arene dibenzo-crowns-6 1 and 2 and thecalix[4]arene-monobenzocrown-6 3 in 1,3-alternate conformationand evaluated their complexation properties towards alkali metal cations in homogeneous solution and in two phase systems, togetherwith their performance in radioactive waste treatment. All data confirm the higher Cs/Na selectivity of the 1,3-alternate calix[4]crown-6 1–3 containing aromatic rings in the polyether loop, in comparison to previously synthesised compounds of the same series.

Calix[n]arene phosphine oxides. A new series of cation receptors for extraction of europium, thorium, plutonium and americium in nuclear waste treatment

A novel class of calixarene derivatives with phosphine oxide residues [Calix-(OCH2CH2POPh2)n] attached to the lower rim showing high efficiency in extraction of EuIII, ThIV, PuIV, and AmIV from simulated nuclear waste is reported.

Cobaltabis(dicarbollide) derivatives as extractants for europium from nuclear wastes

Carbon substituted derivatives of [3,3′-Co(1-Me-2-R-1,2-C2B9H9)2]– incorporating lipophilic chains [R = (CH2)3O(CH2)2OMe 1, (CH2)3OCH2CHMe2 2, (CH2)6O(CH2)3Me 3, (CH2)3Me 4], are synthesized for the first time and tested for extraction of 152Eu; compound 3 showed the best performance, and it proved to have higher efficiency in transport at low acidity than the well known calixarene derivatives.

Aromatic substituted metallacarboranes as extractants of 137Cs and 90Sr from nuclear wastes

Phenyl- and 1,2-diphenyl-1,2-dicarba-closo-dodecaborane have been synthesized and deboronated to yield [7-C6H5-7,8-C2B9H11]– and [7,8-(C6H5)2-7,8-C2B9H10]–. Reaction of the monophenyl with KOBut and CoCl2 in 1,2-dimethoxyethane (dme) led to [3,3′-Co(1-C6H5-1,2-C2B9H10)2]– 1–. This has been fully characterized by X-ray analysis. A similar reaction with [7,8-(C6H5)2-7,8-C2B9H10]– did not yield the expected sandwich compound. On the contrary, reaction of [7,9-(C6H5)2-7,8-C2B9H10]– with KOBut and CoCl2 in a mixture of dme and diethylene glycol dimethyl ether led to [3,3′-Co{1,7-(C6H5)2-1,7-C2B9H9}2] 2–. The two sandwich complexes were tested for liquid–liquid extraction and transport through supported liquid membranes of 137Cs, 90Sr and 152Eu. Extractions for 137Cs were very good at pH 3 but decreased considerably at pH 1 for H[1], while H[2] showed good efficiency even at this pH. The extraction of 90Sr was performed with the incorporation of a synergistic linear polyether and was good at pH 3 and 1. For the extraction of 152Eu, compound H[2] displayed good efficiency. Transport experiments of Cs using supported liquid membranes were performed with H[1] and H[2] and o-nitrophenyl hexyl ether as the membrane solvent. The permeability of 137Cs for compound H[2] was 30.9 cm h–1 while for H[1] it was 7.95 cm h–1. These permeabilities are much higher than those of usual carriers under comparable conditions.

SYNTHESIS OF DIPHOSPHINE DIOXIDES FOR EXTRACTION OF ACTINIDES USING SUPPORTED LIQUID MEMBRANES TECHNOLOGY

A recurrent method for synthesis of linear and macrocyclic diphosphine dioxides has been applied to synthesize new phosphoryl ligands with P-C bonds, stable in strongly acidic aqueous solution and therefore useful for extraction and recovering of actinides from nuclear wastes. The influence of the structural parameters on their liquid-liquid extraction properties of plutonium and neptunium is studied. Plutonium and Neptunium can be removed from radioactive contaminated liquid wastes, using the supported liquid membrane technology with the more lipophilic organophosphorus extractants, which are a promising alternative to the CMPO (a carbamoylmethylphosphine), currently used for such extractions.