Bifunctional Phosphinic Acid Resins for the Complexation of Lanthanides and Actinides

Abstract

Phosphinic acid ion exchange/redox resins are synthesized by the reaction between polystyrene beads and phosphorus trichloride followed by base hydrolysis. The reaction requires a temperature of 73°C for full functionalization to occur. The effect of lower functionalization temperatures on resin acid capacity was determined and the concomitant effect on ion exchange investigated. The acid capacity was found to vary from 1.68 mequiv/g to 4.79 mequiv/g in the functionalization temperature range studied (15°C to 73°C). The percent resin sites loaded with zinc ions is independent of the actual capacity. The extracting ability of the phosphinic acid resin for europium, thorium, uranium, americium, and plutontutn was examined as a function of acid concentration from acid nitrate solutions both at varying and constant ionic strength. The phosphinic resins show better extraction for these ions than the sulfonic resins, especially from high acid solution (4M HNO₃) due to the superior coordination ability of the phosphoryl oxygen. They also show a higher selectivity for the ions tested over sodium. For example, under conditions where sulfonic resins absorb 85% of the plutonium in solution, the phosphinic acid resins absorb 99.7%.     

RECOVERY OF URANIUM FROM ACID MEDIA BY MACROPOROUS BIFUNCTIONAL PHOSPHINIC ACID RESIN

ABSTRACT

The extraction of uranium from various acid media such as nitric acid, sulphuric acid, hydrochloric acid, phosphoric acid and perchloric acid by a macroporous bifunctional phosphinic acid resin (MPBPA) has been studied. The distribution coefficients for the extraction of uranium by the MPBPA resin are compared with the corresponding values reported in literature for the conventional sulphonic acid resin. The results clearly indicate the suitability of the MPBPA resin to recover uranium from different types of acid solutions of widely ranging acidities.     

LIQUID - LIQUID EXTRACTION OF GALLIUM(m) FROM ACIDIC NITRATE MEDIA WITH BIS(2-ETHYLHEXYL) PHOSPHINIC ACID IN TOLUENE

ABSTRACT

The distribution equilibria of gallium(III) between bis(2-ethylhexyl) phosphinic acid dissolved in toluene and acidic aqueous nitrate media has been investigated as a function of the concentration of extractant in organic phase and concentration of hydrogen ion and gallium(III) ion in aqueous phase. The extraction characteristics of bis(2-ethythexyl) phosphinic acid are compared with that of bis(2-ethylhexyl) phosphoric acid to get further information. The stoichometry of the extracted species is determined on the basis of slope analysis and IR spectra. Gallium is extracted by a cation exchange mechanism as GaRs₃ by bis(2-ethylhexyl) phosphinic acid and as GaRs₃-HR by bis(2-ethylhexyl) phosphoric acid. Temperature dependence of the extraction equilibrium is examined by temperature variation method. Both extraction processes are endothermic in nature and increase in temperature is favorable.     

REILLEXTM HPQ: A NEW,MACROPOROUS POLYVINYLPYRIDINE RESIN FOR SEPARATING PLUTONIUM USING NITRATE ANION EXCHANGE

Anion exchange in nitric acid is the major aqueous process used to recover and purify plutonium from impure scrap materials. Most strong-base anion exchange resins incorporate a styrene-divinylbenzene copolymer. A newly available, macroporous anion exchange resin based on a copolymer of l-methyl-4-vinylpyridine and divinylbenzene has been evaluated. Comparative data for Pu( IV) sorption kinetics and capacity are presented for this new resin and two other commonly used anion exchange resins. The new resin offers high capacity and rapid sorption kinetics for Pu( IV) from nitric acid, as well as greater stability to chemical and radiolytic degradation     

EXTRACTION OF ACTINIDES BY BIFUNCTIONAL PHOSPHINIC ACID RESIN

ABSTRACT

The extraction of U(VI), Am( III), Pu( IV), Np( IV) and ThIV) by bifunctional phosphinic acid resin of various cross linkages is reported as function of nitric acid concentration. From the comparison of the distribution coefficient values it is suggested that the recovery of these actinide elements from waste solutions as we II as their mutual separations is possible by using phosphinic acid resin.     

EXTRACTION AND SEPARATION OF HEAVY RARE EARTH(III) WITH EXTRACTION RESIN CONTAINING DI(2,4,4-TRIMETHYL PENTYL) PHOSPHINIC ACID (CYANEX 272)

ABSTRACT

Extraction resins, of the type of Levextrel, (which is a collective term for styrene/divinylbenzene based copolymers of predominantly macroporous structure that contain a selective extractant) are important for the recovery and separation of metal ions, as they combine features of solvent extraction and ion exchange resins. This paper presents the results of the adsorption of heavy rare earth ions (Ho(III), Er(III), Tm(III), Yb(III), Lu(III) and Y(II1)) from hydrochloric acid solutions at 0.2 mol/L ionic strength and 50°C by the extraction resin containing di (2,4,4-trimethyl pentyl) phosphinic acid (Cyanex 272) and the chromatographic separation of (Er(III), Tm(III) and Yb(III)). Technological separation products, with purity and yield of Tm₂O3 >99.97%, >80%; Er₂O₃ >99.9%, >94% and Yb₂O₃ >99.8%, >80% respectively, have been obtained from a feed having the composition Tm₂O₃ 60%, Er₂O₃ 10%, and Yb₂O₃ 3%, the others 27%.

The distribution coefficients, extraction equilibrium constants and separation factors have been determined as a function of acidity, loading of the resin and rare earths, flow rates and column ratios. The resolutions and efficiencies of separation of Er/Tm/Yb each other have been calculated. The stoichiometry of the extraction of rare earth ions has been suggested as well.     

Synthesis and Surface Modification of Mesoporous Silicate SBA‐15 for the Adsorption of Metal Ions

Abstract

In this study surface modified SBA‐15, coated with octadecyltrichlorosilane (C18), is considered as an alternative adsorbent for metal ions in water. The SBA‐C18 was loaded with Bis(2,4,4-trimethylpentyl) phosphinic acid (cyanex 272) as the metal ion extractant. The adsorption characteristics of phosphinic acid loaded SBA‐C18 were evaluated for Cu(II) and Zn(II) ions in aqueous solution. Adsorption tests indicated that a contact time of 1 hour was sufficient for adsorption equilibrium to occur. The pH_1/2 values of Zn(II) and Cu(II) onto SBA‐C18, were found to be similar to published data for levextrel ion exchange resins and around 1 pH unit lower than published solvent extraction data for cyanex 272 in xylene.     

Synthesis and characterization of a bifunctional ion exchange resin with polystyrene-immobilized diphosphonic acid ligands

A new ion exchange resin for the selective complexation of metal ions has been synthesized by functionalizing vinylbenzyl chloride-styrene-divinylbenzene copolymer beads with the sodium salt of tetra(isopropyl) methylene diphosphonate. The effects of bifunctionality, matrix rigidity, degree of functionalization, and macroporosity on final resin properties have been quantified. A sulfonic acid-diphosphonic acid bifunctional resin is highly selective with rapid complexation kinetics. A macroporous polymer matrix crosslinked with 10% divinylbenzene provides optimum results; for example, 99.7% Eu(III) is complexed from a 1M nitric acid solution with a 30-min contact time. The importance of physical crosslinking as well as chemical crosslinking in limiting access of substrates into polymer-supported reagents is discussed. © 1996 John Wiley & Sons, Inc.     

KINETICS OF URANIUM EXTRACTION BY MACROPOROUS BIFUNCTIONAL PHOSPHINIC ACID RESIN

ABSTRACT

The rate of extraction of uranium by macroporous bifunctional phosphinic acid (MPBPA) resin from nitric acid medium has been studied under particle diffusion controlled conditions. The internal diffusion coefficient was found to increase with increase in temperature and decrease with increase in particle size. The activation energies and entropies suggest that the extraction of uranium essentially follows ion exchange mechanism at low concentration of nitric acid while it is through linkage of >P=0 group of the resin at high concentrations.     

Evaluation of New Anion Exchange Resins for Plutonium Processing

Abstract

This paper presents the results of studies comparing the performance of two new anion exchange resins for plutonium processing with the well proven and widely used benchmark, Dowex 1X4 resin. In this connection, the experiments on distribution ratio measurement of plutonium as a function of nitric acid concentration, Pu(IV) sorption kinetics, chemical, thermal, and radiation degradation of the two commercially available anion exchange resins namely, Tulsion A‐PSL 4 and Tulsion A‐PSL 6 have been studied, vis‐à‐vis the benchmark. Tulsion A‐PSL 6 was found to have higher plutonium sorption capacity and polymer matrix stability as well as better kinetics of sorption than the other two resins, while Tulsion A‐PSL 4 and Dowex 1X4 were found to have comparable sorption capacity, kinetics, and resistance to chemical and radiation degradation. The small‐scale evaluation of these new anion exchange resins shows that they can be used for the purification and concentration of plutonium.     

Solid–liquid extraction of terbium from phosphoric acid solutions using solvent‐impregnated resin containing TOPS 99

BACKGROUND: In this work, the solid‐liquid extraction of terbium from phosphoric acid solutions using solvent‐impregnated resin containing TOPS 99, an equivalent of di‐2‐ethylhexyl phosphoric acid, has been investigated. The parameters studied include equilibration time, acid concentration, amount of resin, metal concentration, kinetics, temperature, loading, elution, regeneration and recycling. RESULTS: FT‐IR results confirm the physical interaction of the extractant with the resin. The extraction of terbium with TOPS 99 impregnated Amberlite XAD 4 resin was acid dependent and transfer of metal follows a cation exchange mechanism. The loading capacity of TOPS 99‐impregnated resin for terbium was calculated to be 23.8 mg g^?1 resin. Controlling mechanism of the adsorption was found to be a chemical reaction following pseudo‐second‐order kinetics. The endothermic nature of extraction was confirmed by temperature studies. Among the various eluants studied, H₂SO₄ was the best. Regeneration and recycling of the resin indicated the resin can be used for continuous cycles. CONCLUSIONS: Terbium was successfully extracted from phosphoric acid using TOPS 99 extractant impregnated into Amberlite XAD4 with a maximum loading of 23.8 mg g^?1 resin and fully recovered with 1 mol L^?1sulfuric acid. The resin was subjected to seven cycles of extraction and elution without any loss of performance. Further studies showed that terbium could be separated from lutetium. Copyright © 2010 Society of Chemical Industry     

Solvent Extraction of Pu(IV) Using TBP: A Comparative Study of n-dodecane and a Room Temperature Ionic Liquid

The extraction of Pu(IV) from nitric acid medium using TBP has been compared with two diluents using n-dodecane and a RTIL, 1-butyl-3-methylimidazolium bis(trifluoromethanesulphonyl)imide (C₄mimTf₂N). Kinetics of extraction was slower in RTIL compared to n-dodecane. The mechanism of extraction was found to be cation exchange at lower acidity which changes to the formation of a neutral complex at higher acidity greater than 1M HNO₃ for RTIL. Back extraction of Pu from the loaded organic phase was equally effected using 0.1M oxalic acid and a mixture of guanidine carbonate and EDTA as strippant from both the extraction systems under study. Radiation stability and reusability studies showed promise for future application.     

MECHANISM OF POLYMER-BASED SEPARATIONS. III. METAL ION LOADING CAPACITIES OF REACTIVE POLYMERS WITH SPECIFIC RECOGNITION MECHANISMS

The metal ion selectivity series displayed by a reactive polymer, the phosphinic acid ion exchange/redox resin, was determined from equinormal solutions of 1 milliequivalent metal ion per milliequivalent of polymer ligand sites and compared to results from trace ion solutions. It was found that intervention by the recognition mechanism (i.e., reduction) with Hg(II) and Ag(I) ions from pH 2 aqueous solutions led to high resin loading capacities. Thus, the phosphinic resin/Hg(II) interaction displayed a log D of 3.88, compared to 3.80 from a 10^-4 N solution, indicating that the recognition mechanism obviated any influence of a loading effect. The loading effect was apparent in Fe(III) complexatign wherein a log D of 4.94 was found from a 10^-4 N solution and 0.40 from the equinormal solution. The solution acidity was also an important determinant of selectivity: the series was Fe > Hg > Mn > Ag from 4N HNO₃ and Hg > Ag > Mn > Fe from 0.01N HN0₃. The performance of the phosphinic acid resin was contrasted to that from the non-reactive (i.e., solely ion exchanging) phosphonic acid resin.     

Ion‐Exchange Separation of Pu from Macro Concentration of Th in HNO3 Medium

Abstract

Sorption behavior of Th and Pu from anion‐ as well as cation‐exchange resin was investigated from nitric acid medium by both batch and column methods. The anion‐exchange studies involved anionic nitrate complexes of Pu⁴⁺ and Th⁴⁺ sorbed onto DOWEX 1x4 resin (50–100 mesh), and the cation‐exchange studies involved the sorption of Pu³⁺ and Th⁴⁺ onto BIORAD AG 50Wx8 (50–100 mesh) or DOWEX 50Wx4 (50–100 mesh) resin. The batch data gave a separation factor (K _d,Pu/K _d,Th) of 22 for the anion‐exchange method and 0.017 for the cation‐exchange method at 3 and 2 M HNO₃, respectively. A two‐stage ion‐exchange separation method was developed for the quantitative separation of Pu (8 g/L) from a macro amount of Th (200 g/L) in nitric acid medium. The first step involved the quantitative sorption of plutonium from the mixture while about 90% of Th could be washed in 6 column volumes. The plutonium, eluted (as Pu³⁺) using 0.5 M HNO₃ + 0.2 M hydrazinium nitrate (HN) + 0.2 M hydroxyl ammonium nitrate (HAN), and the residual (～10%) Th were subsequently loaded onto a cation‐exchange column in the second step. Greater than 99% Pu was recovered with 2 M HNO₃ (in ～8 column volumes) containing 0.2 M HN + 0.2 M HAN. The final elution of thorium from the cation‐exchange column was achieved in about 6 column volumes of 1 M α‐hydroxy isobutyric acid. A (Pu, Th)O₂ fuel scrap sample was dissolved in 16 M HNO₃ containing 0.005 M HF and was used subsequently as the feed for the anion‐exchange column. The eluted Pu was subsequently loaded onto a cation‐exchange column for final purification. The recovery of plutonium and thorium was found to be >99% and >98%, respectively, while the respective decontamination factors were estimated to be 215 and 292.     

EXTRACTION OF PLUTONIUM BY CHELATING HYDROXYPYRIDINONE AND CATECHOLAMIDE RESINS∗

ABSTRACT

Four new chelating hydroxypyridinone and catecholamide polystyrene-supported extractants have been prepared and evaluated for their ability to selectively remove ppm levels of plutonium from a variety of acidic aqueous waste compositions. The hydroxypyridinone and catecholamide ligands, modeled after the metal ion binding sites found in siderophores, were derivatized to allow covalent attachment to a polymeric support. The synthesis, loading capacities and chemical stability of the new resins are reported along with the results from extraction studies evaluating their performance for the extraction of Pu(IV) and Pu(VI) from a variety of HNO₃ and NaN0₃ solutions up to 5 M and in competition with Fe(III), Al(III), Zr(IV) and EDTA. The kinetics of metal ion sorption onto the resins are fast, and the extraction results are compared to the commercial Chelex resin.     

Novel Bifunctional Resins in Metal Ion Separations: Ion Exchange/Coordination Resins and Ion Exchange/Precipitation Resins

Abstract

Dual mechanism bifunctional polymers (DMBP's) as metal ion extractants are described within the context of two new examples. The carboxylic acid/pseudocrown resin is a new example of the DMBP class of resins described as ion exchange/ coordination resins. The polyethylene glycol ligand within the resin functions as a coordinating site for metal ions which are brought into the resin via ion exchange with the acid ligand. Initial studies with alkali metal ions are presented. The third general class of DMBP's is also presented. In this case, precipitation is the reaction occurring along with ion exchange thus yielding the ion exchange/precipitation resins. Barium recovery from aqueous solution via barium sulfate precipitation is described.     

Preparation and characterization of UV‐grafted ion‐exchange textiles in continuous electrodeionization

Ion‐exchange textiles (IETs) suitable for use in continuous electrodeionization (CEDI) stacks were prepared using the ultraviolet (UV)‐induced grafting of acrylic acid and sodium styrene sulfonate for cation‐exchange textiles, or 2‐hydroxyethyl methacrylate and vinylbenzyl trimethyl ammonium chloride for anion‐exchange textiles, onto nonwoven polypropylene fabric using benzophenone as photoinitiator. Although the ion‐exchange capacity (2.2 meq g^?1) of the prepared strong acid cation‐exchange textile was lower than that of IRN77 strong acid cation‐exchange resin (4.2 meq g^?1), the overall rate constant of IET was very high due to its low crosslinking and high specific surface area. There was no significant difference between the two different media in terms of the Co(II) removal rate. Furthermore, the current efficiency for IETs was higher than that of IRN77 cation‐exchange resin during a CEDI operation, with efficiencies of 60% and 20%, respectively. The IET also showed the faster exchange kinetics. Therefore, IETs prepared in this study proved to have desirable ion‐conducting characteristics within the CEDI systems. Also this study revealed that the primary removal mechanism in CEDI is the transport of ions through a medium and not the ionic capacity of a medium. Copyright © 2004 Society of Chemical Industry     

Studies on the Sorption of Palladium using Cross‐Linked Poly (4‐Vinylpyridine‐Divinylbenzene) Resins in Nitric Acid Medium

Various cross‐linked (4, 8, and 12%) gel‐type weak‐base poly(4‐vinylpyridine) (PVP) resins were studied for palladium recovery from nitric acid medium. The sorption of palladium was found to decrease with an increase in cross‐linkage of the resin. 8 and 12% PVP resins exhibited maximum D _Pd(II) values at 2–6 M HNO₃, whereas 4% PVP resin showed maximum D _Pd(II) values at lower acidities (0.1 M HNO₃). FT‐IR, SEM, and XPS techniques were used for the characterization of palladium‐loaded resins. Detailed studies were carried out with the resin of modest cross‐linkage i.e., 8% PVP resin. The sorption isotherm studies revealed that the maximum palladium loading approaches the theoretical capacity of the resin, presuming the sorption of palladium as divalent anion at 4 M HNO₃. The pseudo‐second order kinetics model yielded the best fit for the experimental data of sorption kinetics. An increase in temperature accelerates the rate of palladium extraction and also the addition of chloride ions increases the palladium uptake. Column studies were performed using 4 and 8% PVP resins in 2 and 4 M nitric acid concentrations. The loaded palladium could be eluted efficiently with acidic thiourea solution.     

MECHANISM OF POLYMER-BASED SEPARATIONS. I. COMPARISON OF PHOSPHINIC ACID WITH SULFONIC ACID ION EXCHANGE RESINS

The metal ion complexing ability of the phosphinic acid polymeric extractant has been compared with that for the sulfonic acid ion exchange resin. Based on the performance of the extractants with Fe(III), Hg(II), and Mn(II) under dilute solution/ high acid conditions, both with and without the presence of a large excess of sodium ions, it is concluded that the phosphinic resin operates through an entropy-driven coordination for hard trivalent ions such as Fe(III), an enthalpy -driven coordination for soft ions such as Hg(II) and only ion exchange for hard divalent ions such as Mn(II). The sulfonic resin operates non-selectively through the ion exchange mechanism.     

Synthesis,Characterization, and Applications of a New Ion Exchanger Tamarind 4-aminobenzoic Acid (TABA) Resin in Industrial Wastewater Treatment

Chromatographic column separations of toxic metal ions from industrial wastewater were achieved in acid media at optimized (K_d) values with a synthesized cation exchange TABA resin. The prepared TABA resin was characterized by FTIR, elemental, and thermogravimetric analysis. Studies of total ion exchange capacity, resin durability, and swelling were carried out. The distribution coefficient values of metal ions, viz Cu²⁺, Fe²⁺, Zn²⁺, Cd²⁺ and Pb²⁺ at different pH, were also studied using a batch equilibration method. The different factors affecting metal ions adsorption on this substrate, such as treatment time, agitation speed, and temperature, were studied in detail.