Extraction Behaviors of Trivalent Lanthanides from Nitrate Medium by Selected Substituted Malonamides

Abstract

The extraction of La(III), Pr(III), Nd(III) Sm(III), Eu(III), Gd(III) Tb(III), Dy(III), and Er(III) from nitrate medium by a series of structurally related malonamides (MA) diluted with toluene has been studied. The considered malonamides were synthesized with different substituting groups including alkyl, cyclohexyl, and oxyalkyl chains. This series allowed for a systematic determination of the effect of the structure on the extraction of trivalent lanthanides. Distribution ratios of the investigated metal ions have been determined as a function of nitric acid concentration, diluent type, extractant concentration and salting‐out agent as well as temperature. The stoichiometries of the extracted species of La(III), Sm(III), Tb(III), and Er(III) were conformed to be tri‐solvates. The extracted species were also studied using IR spectra.     

Separation and concentration processes of solutions of Co(II), Ni(II), Cr(III), Fe(III) and Mn(II) by extraction with toluene-dissolved rosin

The extraction and stripping of Co(II), Ni(II), Cr(III) and Fe(III) from aqueous solutions by rosin dissolved in toluene has been investigated. Results obtained show that rosin is better extractant than abietic or n-lauric acids under comparable conditions. From these results, and the data of Mn(II) solvent extraction studied previously under the same conditions, a separation and concentration process for these five cations in aqueous solutions has been designed. Saturated solutions of Fe(III), Cr(III), Mn(II) and finally Co(II) and Ni(II) have been obtained successively by extraction and stripping, by addition of ammonium hydroxide to obtain the appropriate pH value, and by modifying adequately the organic phase/aqueous phase volume ratio.     

Application of N,N′‐Dimethyl‐N,N′‐Di(4‐Chlorophenyl)Tetradecyl Malonamide for the Selective Recovery of Iron(III) from Concentrated Chloride Solutions

Abstract

The feasibility of using two new diamides namely; N,N′‐dimethyl‐N,N′‐di(4‐chlorophenyl)malonamide (DMDPhClMA) and N,N′‐dimethyl‐N,N′‐di(4‐chlorophenyl)tetradecylmalonamide (DMDPhClTDMA), as agents for the selective extraction of iron(III) from chloride solution was investigated. A systematic investigation has been carried out on the detailed extraction properties of iron(III) with these extractants from chloride media. The extraction of iron(III) from an aqueous chloride solution in the presence of metal ions, such as Zn(II), Co(II), Mn(II) Cu(II), Pb(II), Ni(II) and Ag(I) was carried out using DMDPhClMA or DMDPhClTDMA in binary and multicomponent mixtures. The quantitative extraction of iron(III) with DMDPhClMA and DMDPhClTDMA in toluene is observed at 4 and 7 M HCl, respectively. The quantitative stripping of Fe(III), from the loaded organic phase was successfully achieved by simple contact with water.     

SELECTIVE EXTRACTION OF PALLADIUM(II) FROM CHLORIDE SOLUTIONS WITH NONYLTHIOUREA DISSOLVED IN CHLOROFORM

ABSTRACT

The extraction of Palladium(II) [Pd(II)] from hydrochloric acid solutions with nonylthiourea (NTH) dissolved in chloroform at a constant ionic strength of 1.0?M has been studied. The extraction of Pd(II) has been investigated as a function of the concentration of the extractant, chloride ion, and proton concentrations as well as extraction temperature. The distribution data have been treated graphically and numerically. The analysis of the experimental data has shown that Pd(II) is extracted as PdCl₂·(NTH) and PdCl₂·(NTH)₂ species with the respective extraction constants of log?K ₁₁=5.0±0.1 and log?K ₁₂=9.1±0.1. The back-extraction of Pd(II) from the organic phase using different stripping reagents has been examined. The selectivity of NTH for Pd(II) against Pt(IV), Rh(III), Cu(II), Fe(III), and Zn(II) has also been investigated.     

PERMEATION OF METAL IONS THROUGH HOLLOW-FIBER SUPPORTED LIQUID MEMBRANES: CONCENTRATION EQUATIONS FOR ONCE-THROUGH AND RECYCLING MODULE ARRANGEMENTS∗

ABSTRACT

p-(l,l,3,3-Tetramethylbutyl)phenyl hydrogen[N,N-di(2-ethylhexyl)amino-methylphosphonate was synthesized as a novel type of extractant to investigate the extraction behavior of base metals as well as of precious metals from aqueous chloride media into toluene. This reagent exhibited high selectivity for platinum (IV) and palladium (II) ions in the low acidic region (0·01 - 6?mol dm^?3) / over base metal ions except for trivalent iron over the whole concentration region under the present experimental conditions. The extraction of platinum and palladium with p-( 1,1,3,3-tetramethylbutyl)phenyl hydrogen[N,N-di(2-ethylhexyl)aminomethyl-phosphonate was higher than that with N,N-di(2-ethylhexyl)aminomethyl-phosphonic acid due to its high lipophilicity. Stripping of the loaded palladium was achieved with an aqueous mixture of I mol dm^?3 thiourea in combination with I mol dm^?3 hydrochloric acid. The extraction reaction of palladium from aqueous chloride media into toluene was found by slope analysis to be described as follows     

Liquid-Liquid Extraction of Ruthenium from Chloride Media by N,N'-Dimethyl- N,N'-Dicyclohexylmalonamide

Abstract

Research on the solvent extraction of ruthenium from hydrochloric acid media has been carried out using N,N'-dimethyl-N,N'-dicyclohexylmalonamide (DMDCHMA) dissolved in 1,2-dichloroethane. Ruthenium extraction percentages (%E) ranging from 50% to 80% have been achieved for HCl concentrations between 5 M and 7 M. Extraction curves exhibiting the dependence of the %E ruthenium on HCl concentration in the aqueous phases are presented, the latter solutions being obtained by dissolution of either Ru(III) or Ru(IV) salts. The influence of some experimental parameters on the %E Ru, such as the equilibration time, extractant concentrations, and hydrogen-ion activities, has been thoroughly investigated. Additionally, DMDCHMA is also adequate for extracting Pd(II) from 5 M to 7 M HCl solutions and under similar experimental conditions, %E Rh(III) is below 5%, and Pt(IV), Ir(III), and Ir(IV) cause the formation of third phases. Both Ru and Pd(II) can be successfully stripped from the loaded organic phases with water. A partition scheme to isolate Ru from a number of some associated elements has also been attempted.     

Solvent Extraction of Copper from Nitrate Media with Chelating LIX‐Reagents: Comparative Equilibrium Study

Abstract

Comparative experimental studies were carried out on extraction of copper(II) cations from aqueous acid nitrate media using four LIX‐reagents, representatives of different extractant classes: LIX 984N‐I, LIX 860N, LIX 84‐I and LIX 65N. As a diluent, liquid hydrocarbon undecane was used. The extraction behavior of the LIX‐reagents was compared based on an analysis of the influence of the main factors on the two‐phase mass transfer process: aqueous pH‐value, initial copper and extractant concentrations, and temperature. The experimental data received were used in the calculation of important parameters characterizing the efficiency of copper extraction from nitrate media with different LIX reagents: distribution ratios D, concentration extraction constants K _ex, pH_0.5‐values, and thermodynamic parameters such as enthalpy, entropy, and free energy changes (ΔH ⁰, ΔS ⁰, ΔG ⁰‐values).     

Highly selective separation and recovery of Pd(II) from the automotive catalyst residue with the thiocarbamoyl substituted azothiacalix[4]arene derivative

New ligand, namely, 5, 11, 17, 23-tetrakis-((p-chlorophenyl) azo)-25,26,27,28-tetrakis ((dimethylthio carbamoyl)oxy) thiacalix[4]arene (CADTTCA), has been investigated for separation and recovery of Pd(II) through solvent extraction technique. Experimental parameters such as contact time, diluents, effect of H⁺ and Cl^? concentration, and acid durability have been thoroughly investigated. The loading capacity toward Pd(II) was determined to be 113 mg/L using 0.25 mM CADTTCA. The extractant showed high selectivity and extractability for Pd(II) than the other metal ions present in automotive catalyst residue (ACR) solution containing platinum group (PGMs) metal ions (i.e., Pd(II), Pt(IV), Rh(II), La(III), Al(III) and Ce(III)). The recovery percentage of Pd(II) was 98% after five extraction-scrubbing-stripping cycles. The probable extraction mechanisms were established through the FT-IR spectral analysis.     

Liquid–Liquid Extraction of Silver From Chloride Media by N,N′-Tetrasubstituted Dithiomalonamide Derivatives

N,N′-dimethyl-N,N′-diphenyldithiomalonamide (DMDPHDTMA) and N,N′-dimethyl-N,N′-dicyclohexyldithiomalonamide (DMDCHDTMA) were synthesized and tested as extractants for silver in chloride solutions. Even when relatively low concentrations are used, both compounds effectively extract Ag(I) from 2–5 M chloride concentrated aqueous phases. Ag(I) is successfully stripped by a stabilized sodium thiosulfate solution. Results obtained from sequential cycles of extraction-stripping suggest that both extractants exhibit a high Ag(I) loading capacity. The effects of the equilibration time, concentrations of extractant, chloride and hydrogen ions on Ag(I) extraction have been investigated. The chemical reactions involved on Ag(I) extraction are proposed. There is no selectivity of DMDPHDTMA or DMDCHDTMA for Ag(I) when Cu(II) and Fe(III) co-exist in the chloride aqueous solution.     

IMPREGNATED RESINS CONTAINING DI-(2-ETHYLHEXYL) THIOPHOSPHORIC ACID FOR THE EXTRACTION OF PALLADIUM(H). II. SELECTIVE PALLADIUM(II) RECOVERY FROM HYDROCHLORIC ACID SOLUTIONS

ABSTRACT

The extraction of Pd(II) from HC1 solutions by impregnated resins containing di-(2-ethylhexyl) thiophosphoric acid (DEHTPA or HL) on the Amberlite XAD2 polymeric support has been studied. Graphical and computer analysis with the program LETAGROP-DISTR demonstrated that the Pd(II) extraction can be explained by the formation of metal complexes in the resin phase having the composition PdL₂(HL)₂. DEHTPA/XAD2 resins extracted Pd(II) in the presence of other metals: Pt(IV), Rh(III), Cu(II), Fe(III) as well as Zn(II). The stripping of Pd(II) loaded on the organic phase and the lifetime of the resins were also investigated.     

NEW XANTHIC ACID DERIVATIVES AS POTENTIAL REAGENTS IN THE SOLVENT EXTRACTION OF PRECIOUS METAL IONS: EXTRACTION OF PALLADIUM(II) WITH 13-BIS(0-BUTYLXANTHATO)PROPANE

ABSTRACT

Two series of new xanthic acid derivatives namely, the bis (O-butylxanthato) alkanes ( abbreviated as BBXAs or simply as bis-xanthates in this paper) have been synthesized in connection with the solvent extraction of precious metal ions. From an aqueous medium containing 0.1 M NaC10₄ (1 M=l mol dm^-3), these compounds exhibited high selectivity for extraction of Pd(II) and Ag(I) in dichloroethane, over most of the base metals as well as Pt(IV) and Au(III) ions. Towards Pd(II) and Ag(I) ions, the bis compounds act as SS chelating agents where the stabilities of the extractable complexes are determined by the length of the alkylene chain existing between the donor atoms. Pd(II) extraction has been studied in detail taking 13-bis(O-n-butylxanthato)propane (BnBXP) as the representative member of the series of bis-xanthates synthesized in this work. The extraction of palladium(II) was found to be quite slow in pure chloride medium. But, a mixed acid medium containing H₂SO₄ or HNO₃ in the presence of smaller amount of chloride ion provided optimum reversible extraction of palladium in dichloroethane, where Pd(II) forms 1:1 extractabic complexes with BnBXP. Pd(II) extraction is described in terms of the aqueous phase compositions, extraction and back-extraction data, extraction equilibrium, selectivity considerations and probable mechanisms of extraction.     

Extraction of rare earth elements from nitrate solution using novel unsymmetrical diglycolamide

A novel unsymmetrical diglycolamide (DGA), namely N,N-dihexyl-N’,N’-didecyldiglycolamide (DHD²DGA), was synthesized for the extraction of Nd(III), Sm(III), Gd(III), Dy(III), Ho(III) and Er(III) in nitric acid solutions. The effects of HNO₃, HCl or H₂SO₄ on the distribution ratio of the investigated metal ions were investigated. A systematic investigation was carried out using DHD²DGA in n-dodecane from nitric acid solutions. The main extracted species of Nd(III), Sm(III), Gd(III), Dy(III), Ho(III) and Er(III) were studied at different nitric acid concentrations by the slope analysis method and the enthalpy change of the extraction reactions was determined. The IR spectra of the extracted species were also investigated. The values of thermodynamic functions for the extraction of the lanthanides were calculated. The obtained results indicated that the effective separation of Ln(III) from Fe(III), Ni(II), Co(II) and Cs(I) can be obtained.     

EXTRACTION BY N,N'-TETRAALKYLMALONAMIDES II.

Suitable N.N'-tetraalkylmalonamldes for Am(III) extraction from concentrated HNO₃ aqueous liquors have been selected. Extraction mechanisms of Eu(III) and Am(III) by NN'-dlmethyldioctylmalonamide (DMDOMA) have been investigated. The distributions ratios of Am(III) and Eu(III) between 1M DMDOMA in t-butylbenzene and per chloric acid are higher than those obtained In nitrate media. Extraction data for Pu)IV), U(VI), Fe(III), Zr(IV) are reported. From these results It can be concluded that the NN'-dlmethyldlal-kylmalonamldes are good extractants for the actinides contained in the radioactive wastes.     

EXTRACTION OF EUROPIUM(III) ION WITH TETRAHEXYLMALONAMIDES

ABSTRACT

The extraction of europium(III) nitrate from sodium nitrate with a series of tetrahexylmalonamides has been investigated. The tetrahexylmalonamides considered were N.N.N’N’-tetrahexylmalonamide (THMA), N,N,N’N’-tetra-hexyl-2-methylmalonamide (MeTHMA), and N,N,N’N’-tetrahexyl-2,2-dimethy-lmalonamide (DiMeTHMA). This series allowed for a systematic determination of the effects of alkyl substitution of the methylene carbon. Equilibrium modeling of the extraction data indicates that the malonamide/Eu ratio in the extracted complexes is 3 for all three malonamides investigated. This stoichiometry is different than that determined for isolated complexes. This can be rationalized by the formation of complexes with monodentate-bound diamide ligands in the extracts. The extraction constant for Eu decreases by seven-fold in going from THMA to MeTHMA, and a precipitous drop in the extraction constant occurs upon substitution of a second methyl group on the methylene carbon (i.e., for DiMeTHMA).     

Synergistic Extraction of U(VI), Th(IV), and Lanthanides(III) from Nitric Acid Solutions Using Mixtures of TODGA and Dinonylnaphthalene Sulfonic Acid

The extraction of U(VI), Th(IV), and lanthanides(III) from aqueous nitric acid solutions with mixtures of N,N,N′,N′-tetra(n-octyl)diglycolamide (TODGA) and dinonylnaphtalene sulfonic acid (HDNNS) in n-decane has been investigated. The extraction efficiency of U(VI), Th(IV), and Ln(III) ions is greatly enhanced by addition of HDNNS to an organic phase containing TODGA. The synergistic effect arises from the higher hydrophobicity of U(VI), Th(IV), and Ln(III) extracted species formed by TODGA and DNNS^? anions as compared to those formed by TODGA and NO₃^? ions as counter anions. The synergistic effect for U(VI), Th(IV), and Ln(III) extraction from aqueous nitric acid solutions with mixtures of TODGA and HDNNS becomes weaker when the acidity of the aqueous phase increases. A high synergistic enhancement is accompanied with a high selectivity of Ln(III) extraction from nitric acid solutions.     

Liquid-liquid distribution of metals in systems with trioctylmethylammonium dinonyl naphthalenesulfonate

The extraction of copper, nickel, cobalt, zinc, and iron chlorides by the solutions of trioctylmethylammonium dinonyl naphthalenesulfonate in toluene depending on the acidity of aqueous phase was studied. In the range of relatively high acidity (from 3 to 1 M HCl), an increase in the D _M values is observed with a growth in the concentration of hydrogen ions in aqueous phase; that corresponds to the principles of the binary extraction of chloro complex metal-containing acids. With a decrease in the acidity of aqueous phase, an increase in the distribution coefficients of metals is observed due to the change in the extraction mechanism and increase in the fraction of the complexes extracted as metal dinonyl naphthalenesulfonates. In the acidic range, the extractability of metals is mainly determined by the stability of complex metal-containing anions and qualitatively corresponds to the following order: Fe(III) > Cu(II) > Co(II) > Ni(II).     

Application of anionic acrylamide‐based hydrogels in the removal of heavy metals from waste water

Crosslinked acrylamide (AM) and 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) homopolymers and copolymers were prepared by free radical solution polymerization using N,N′‐methylenebisacrylamide as the crosslinker. The chemical structures of hydrogels were characterized by FTIR analysis and the results were consistent with the expected structures. These hydrogels were used for the separation of Cd(II), Cu(II), and Fe(III) ions from their aqueous solutions. The influence of the uptake conditions such as pH, time and initial feed concentration on the metal ion binding capacity of hydrogel was also tested. The selectivity of the hydrogel towards the different metal ions tested was Cd(II) > Cu(II) > Fe(III). It was observed that the specific interaction between metal ions and ionic comonomers in the hydrogel affected the metal binding capacity of the hydrogel. The recovery of metal ions was also investigated in acid media. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Palladium Extraction from Nitric Acid Solutions by LIX 84 and LIX 860-I

ABSTRACT

The extraction of Pd(II) from weakly nitric acid solutions by LIX 84 (2-hydroxy-5-nonylacetophenone oxime) and LIX 860-I (5-dodecylsalicylaldoxime) dissolved in toluene has been studied and compared from the viewpoint of extraction equilibria. The effects of pH, nitrate ions and metal and extractant concentrations on the palladium distribution ratio have been quantified. The extraction rate of Pd(II) from this media is slow but the metal is quantitatively extracted by adding just the stoichiometric amount of the extractants. The experimental data have been treated graphically and numerically by means of the Letagrop-Distr program and can be explained by assuming the formation of the chelate PdL₂. Values of the extraction constants are also given.     

Palladium Extraction by a Malonamide Derivative (DMDOHEMA) from Nitrate Media: Extraction Behavior and Third Phase Characterization

Liquid-liquid extraction of palladium(II) from nitric media was carried out using, N,N’–dimethyl,N,N’-dioctylhexylethoxymalonamide (DMDOHEMA) in n-heptane. To this purpose, various experimental parameters such as reaction time, extractant concentration, pH, and nitrate concentration were investigated in detail. Efficient extraction of palladium can then be achieved, with good distribution coefficients (D up to 10) and performing kinetics (equilibration time ca. 30 min). In some cases, a solid phase appears at the interface between aqueous and organic layers. It was characterized as a palladium(II) complex with DMDOHEMA with appropriate techniques, and the conditions of its formation are discussed.     

A New Sorbent for Selective Separation of Metal: Polyethylenimine Methylenephosphonic Acid

Abstract

A new sorbent, the polyethylenimine methylenephosphonic acid (PEIMPA), was synthesized from commercially available polyethylenimine. After characterization by (¹H, ¹³C, ³¹P) NMR, elementary analysis, UV/VIS and FTIR, the new ion exchange polymer PEIMPA has been investigated in liquid – solid extraction of a mixture of Cd(II), Co(II), Cu(II), Fe(III), Ni(II), Pb(II), and Zn(II) cations from a mineral residue of zinc ore dissolved in nitric acid. The selectivity of this polymer was studied as a function of pH. PEIMPA can sorb much higher amounts of Fe ion than Cd, Co, Cu, Ni, Pb, and Zn ions. The recovery of Fe(III) is almost quantitative. Because of this remarkable affinity, the PEIMPA resin has the potential for application in several fields. Further studies of the polymer are in progress.