Solvent extraction of lanthanoid/III/ with 18-crown-6 from aqueous trichloroacetate solutions to 1,2-dichloroethane

Extraction behaviour of lanthanoid/III/ has been investigated by using 18-crown-6/CR/ as a neutral microcyclic ligand, trichloroacetate/TCA^–/ as an anionic counter ion, and 1,2-dichloroethane as an organic solvent. From the equilibrium studies, the extractable complex such as LnCR³⁺ was found for La/III/, Ce/III/, Pr/III/, Nd/III/, Sm/III/, and Eu/III/ and also the formation of Ln/CR/ ₂ ³⁺ complexes was suggested for Tb/III/, Tm/III/, and Lu/III/. The extractability of lanthanoid/III/ steeply decreased with increase in the atomic number. This order of extractability was a reverse trend compared with that in many other extraction systems reported so far. Very high separation factors especially among light lanthanoid/III/ were observed.     

Spectrophotometric determination of palladium using 4-methyl-l ,2-cyclohexanedionedioxime

A procedure for the determination of palladium with 4-methyl-1,2-cyclohexanedionedioxime by an extraction -spectrophotometric method has been developed. Interference by coppcr(II), cobalt(Il), iron(II), or iron(III) can be eliminated by suitable masking agents. Ruthenium(III) must be absent or separated prior to the determination of palladium. The molar absorptivity of the bis(4-methyl-1,2-cyclohexanedionedioximato-N,N') palladium(II) complex has been calculated and found to be 1.51?10⁴ 1/moles-cm in chloroform at 280 mμ.     

Extraction and separation of mercury from toxic elements arsenic,cadmium, antimony and thallium,and other metal ions

Extraction of mercury with 3-methyl-1-phenyl-4-trifluoroacetyl-pyrazolin-5-one /FAP/ in chloroform has been described. Maximum extraction /97.3%/ and a distribution coefficient /D/ of 36.5 have been achieved at pH 8. Among the anions tested, thiourea, thiosulphate and cyanide mask the extraction of mercury. Solution of O. 2M KCN was found most suitable stripping agent for mercury. Decontamination data show that mercury can be separated from toxic elements arsenic, cadmium, antimony and thallium; and from other metal ions i. e. Ga/III/, In/III/, Ge/IV/, Sn/II/, Fe/II/, Ir/IV/ and Pt/IV/. A few separations of analytical and radiochemical importance have been discussed.     

Evaluation of unsymmetrical dithiodiglycolamide as novel extractant for application in selective separation of palladium(II) from aqueous solutions

A novel unsymmetrical multidentate ligand namely; N,N'-dimetyl-N,N'-didecyldithiodiglycolamide (DMD³TDGA) was synthesized and used as agent for the selective extraction of palladium(II) from hydrochloric acid solutions. A systematic investigation was carried out on the extraction of Pd(II) using DMD³TDGA. The quantitative extraction of Pd(II) with DMD³TDGA in n-dodecane is observed at ~4 M HCl. The main extracted species of Pd(II) is PdC_l2. DMD³TDGA and IR spectra of the extracted species were investigated. The extraction of palladium(II) from various concentrations of hydrochloric acid solutions in the presence of metal ions, such as Pt(IV), Rh(III), Cr(II), Ni(II), Fe(III), Nd(III), Zr(II), and Mn(II) was carried. DMD³TDGA showed very high selectivity and extractability for Pd(II). Quantitative back extraction of Pd(II) was obtained in single contact using thiourea solution. The results obtained indicated that, excellent separation of Pd(II) from the investigated metal ions can be achieved. Five successive cycles of extraction/back-extraction, indicating excellent stability and re-utilization of this new extractant can be used for selective separation of Pd(II) from other elements in hydrochloric acid medium.     

Solvent extraction separation of In/III/-Tl/III/ and Hg/II/-Cd/II/-Co/II/ with sulphoxides

Solvent extraction studies have been made on some metals: In/III/-Tl/III/ and Hg/II/-Cd/II/-Co/II/, from ammonium thiocyanate solutions by dialkyl sulphoxides. Separation of these metals from one another can be achieved by suitable choice of the extracted conditions. The nature of the extractable metal species has been elucidated.     

Extraction of Palladium(II) and Platinum(IV) from Hydrogen Chloride Solutions with 3,7-Dimethyl-5-thianonane-2,8-dione and Complexation of This Reagent with the Platinum Metals

Extraction of palladium(II) and platinum(IV) from acidic chloride solutions with solutions of 3,7-dimethyl-5-thianonane-2,8-dione in toluene and chloroform and complexation of this reagent with platinum metals in aqueous acetone were studied by ^1Hand ^13C NMR and IR spectroscopy. The possibility of extractive separation of palladium(II) from platinum(IV) and their separation from Cu(II), Ni(II), Co(II), Mn(II) and Fe(III) with solutions of 3,7-dimethyl-5-thianonane-2,8-dione in organic solvents was studied. The apparent concentration constants of extraction of palladium(II) and platinum(VI) with 3,7-dimethyl-5-thianonane-2,8-dione and the corresponding thermodynamic parameters were determined.     

Radiation decomposition of metal acetyl acetonates

Studies on the thermal decomposition of the acetyl acetonate complexes of transitional metal ions Cu/II/, Cr/III/, Mn/II/, Co/II/, Fe/III/, Vo/II/, Zn/II/, and Cd/II/ have been performed by thermogravimetric method. Taking the initial decomposition temperature as a measure of thermal stability, the relative order of the thermal stability of these complexes shows the following order: Zn/II/<Cd/II/< VO/II/<Fe/III/<Cr/III/<Cu/II/Co/II/< Mn/II/. The nature of decomposition of Cu/II/ and Cr/III/ complexes is similar, a sigmoid curve exists. In other cases a long linear decomposition follows the sigmoid pattern. The linear decomposition is a function of final decomposition temperature and percentage of decomposition. The kinetics of the decomposition is analyzed according to the Coats-Redfern equation. The results are discussed on the basis of structural and other aspects leading to the decomposition.     

Sorption-spectrometric determination of palladium and gold using silica chemically modified with dipropyl disulfide groups

It has been found that silica chemically modified with dipropyl disulfide groups (DPDSS) quantitatively extracts palladium(II) from solutions in the acidity range from 4 M HCl to pH 4 and gold(III) in the range from 1 M HCl to pH 2 with a partition coefficient at the level of n × 10⁴ cm³/g. The adsorption of palladium(II) and gold(III) at room temperature is highly selective, whereas non-ferrous and other platinum metals are not adsorbed. Sorption-atomic absorption, sorption-ICP-atomic emission, and sorption-photometric methods for the determination of palladium and gold have been developed using DPDSS. The accuracy of the methods was tested by the analysis of certified reference samples.     

Solvent extraction separation of T1/I/ from T1/III/ with sulphoxides

A method for the separation of microgram quantities of T1/I/ and T1/III/ from hydrochloric acid solutions has been developed. T1/III/ was extracted as HTlCl₄ into benzene by di-n-pentyl sulphoxide /DPSO/ and di-n-octyl sulphoxide /DOSO/. Conditions for the effective extraction of T1/III/, free from T1/I/, have been worked out.     

Extraction of Pd(II) by some petrochemical products from nitrate media

Liquid-liquid extraction of divalent palladium by solutions of Diesel oil (D.O.) and gas oil II (G.O.II) in benzene and lacquer petroleum from nitrate media has been studied. Palladium in concentrations of ∼10⁻³M is very effectively extracted by dilute solutions of extraction reagents and the distribution of palladium is almost independent of the acidity and nitrate concentration of the aqueous phase. Of other common salts, chlorides, thioeyanates and nitrites affect the palladium distribution. In many cases high concentrations of salts completely suppress the extraction of palladium. The rate of palladium extraction by dilute solutions of extractants is relatively small. Some substances such as dimethyl sulfoxide (DMSO) were found to accelerate the extraction. Palladium extraction from nitric acid media also has been studied from the points of view of chemical and radiation stability. Diesel oil was found to be a more stable extraction reagent in acid media than gas oil II.     

Polarographic Determination of Palladium(II) in Rocks After Extraction with [5-(4-Dimethylaminebenzylidene)rhodanine] and Methyl Isobutyl Ketone

Abstract

A sensitive and selective method for the determination of palladium(II) in mineral veins of quartz, a pegmatite rock from Campo Largo County, Parana State, Brazil, was investigated. After liquid-liquid extraction of Pd^2- from aqueous solution, pH 2.4, with [5-(4-dimethylaminebenzylidene)rhodanine] and methyl isobutyl ketone, the back-extraction was performed with 3.0 mol.L^?1 sulfuric acid. At pH 2.4, only trace amounts of gold(III) and silver(I) were co-extracted with palladium(II). However, neither Au³⁺ nor Ag⁺ interfere with palladium(II) determination by differential pulse polarography using tris(hydroxymethyl)aminomethane and potassium nitrate, pH 11.0, as supporting electrolyte. The observed detection limit was 1.0 μg(Pd²⁺).L^?1.     

Liquid–liquid extraction of palladium(II) and gold(III) with N-benzoyl-N′,N′-diethylthiourea and the synthesis of a palladium benzoylthiourea complex

N-Benzoylthioureas have been reported to form complexes with gold (III) and palladium (II) and other transition metals. In this study, an N-benzoyl-N′,N′-diethylthiourea (3f) ligand was used in the solvent extraction of palladium(II) and gold(III) from aqueous chloride media (0.1 mol l−1 NaCl). The distribution coefficient was determined as a function of both metal concentration in the aqueous phase and extractant concentration in the organic phase. The experimental distribution data were numerically analysed by letagrop-distr software in order to obtain the thermodynamic model corresponding to the metal extraction. It is found that pH does not affect the metal extraction process in the 1–2 pH range. Synthesis of the palladium benzoyl thiourea complexes was carried out by mixing quantities of metal and ligand solutions in methanol in a 1:2 ratio stoichiometric. Yields of 74 and 80.9% were obtained for the Pd-3c and Pd-3f complexes. In order to confirm the formation of the palladium complexes, NMR, FTIR and MS analyses were performed. From MS analyses a complex stoichiometry 1:2 (metal:ligand) was confirmed. The formation of crystals of palladium N-benzoyl-N′,N′-diethylthiourea complex (Pd-3f) in the methanolic solution allows the characterisation of the complex structure by XRD. The resulting structure is described and discussed. Bis(1,1,-diheptadecyl-3-benzoyl-thioureate)palladium(II) (Pd-3c) and bis(1,1,-diheptadecyl-3-benzoyl-thioureate)palladium(II) (Pd-3f) were used as ionophores in polymeric membrane electrodes. Their potentiometric responses to different anionic metal chlorocomplexes are evaluated and discussed taking into consideration the results obtained in the liquid–liquid distribution studies. A nernstian response was only obtained for AuCl4 − (PDL=8.8×10−8) and PdCl4 2− (PDL=1.5×10−4 M) with a selectivity coefficient of KAuCl4-, PdCl42−pot=−3.4, calculated taking AuCl4 − as being the primary anion.     

Speciation of Pu ions by differential pulse polarography

By means of differential pulse polarography, Pu ions of different oxidation states have been investigated in 1M Na₂CO₃ solution. Redox reactions of Pu/III/, Pu/IV/, Pu/V/ and Pu/VI/, which are mostly of irreversible nature, have been observed within the potential range of the dropping mercury electrode /DME/, from 0 to –1.5 V, against a Ag/AgCl/NaCl (3M) reference electrode. Based on the peak potential observed for each reaction, the stability of a given oxidation state in the solution could be ascertained. The redox potential of the Pu/IV/–Pu/III/ pair, which was found to be –1.0 V, indicated that the Pu/IV/ carbonate complex was of high stability. The detection sensitivity of the Pu/IV/ ion was found to be 1×10^–6M.     

Tri-n-octylphosphine sulfide: : A selective organic extractant

Tri-n-octylphosphine sulfide (TOPS) has been investigated as the stationary phase in reversed-phase partition paper Chromatographie separations using nitric or hydrochloric acids as the mobile phase. TOPS has also been studied as an extractant for metal ions. Silver, mercury (II), and palladium (II) were found to have RF values of zero when nitric acid was used as the mobile phase. These same ions were also selectively extracted from aqueous nitric acid solutions. Gold(III), mercury(II), palladium (II), and platinum (IV) were found to have RF values of zero when hydrochloric acid was used as the mobile phase. However, only gold(III) and mercury(II) were extracted from aqueous hydrochloric acid solutions in liquid-liquid extraction systems. Several separations were successfully performed from 1 M nitric acid.     

Synergistic extraction and spectrophotometric determination of palladium(II), iron(III), and tellurium(IV) at trace level by newly synthesized p-[4-(3,5-dimethylisoxazolyl)azophenylazo]calix(4)arene

A spectrophotometric method for the determination of palladium, iron and tellurium from nitric acid media after extraction of their p-[4-(3,5-dimethylisoxazolyl)azophenylazo]calix(4)arene [DMIAPAC] complexes has been developed and possible synergistic effects have been investigated. Chloroform, carbon tetrachloride, cyclohexane, 1,2-dichloroethane, toluene and xylene were used as the diluents. The maximum enhancement was obtained in the presence of 30% 1,2-dichloroethane. The trace amounts of metals were determined spectrophotometrically. Beer’s law obeyed in the concentration range of 5.0–95.0 μg, 8.0–120.0 μg and 10.0–140.0 μg/10 mL of the final solution of palladium, iron and tellurium, respectively. The molar absorptivities (l mol^?1cm^?1) and Sandell’s sensitivities (μg cm ^?1) were calculated: Pd(II) = 1.73 × 10⁴ and 0.0061; Fe(III) = 1.08 × 10⁴ and 0.0052; Te(IV) = 1.67 × 10⁴ and 0.0077. Ten replicate analyses containing 20 μg of Pd(II), 12.5 μg of Fe(III) and 32 μg of Te(IV) gave mean absorbance of 0.326, 0.242 and 0.418 with relative standard deviation of 0.36, 0.65 and 0.82% for Pd(II), Fe(III) and Te(IV), respectively. The interference of various ions was studied and optimum conditions were developed for the determination of these metals in certain alloys and synthetic mixtures.     

Solvent extraction of Cobalt/II/ from thiocyanate solutions by sulphoxides

The extraction of cobalt/II/ from ammonium thiocyanate solutions by di-n-pentyl sulphoxide /DPSO/, di-n-octyl sulphoxide /DOSO/ and their mixtures in carbon tetrachloride has been studied. The species extracted were found to be Co/SCN/₂. 4S /where S=DOSO or DOSO/. Synergic effects have been observed which are ascribed to the formation of mixed ligand metal complexes. The influence of the metal concentration, temperature and the diluent on the extraction of cobalt/II/has been investigated.     

A sensitive and selective method for determination of gold(III) based on electrothermal atomic absorption spectrometry in combination with dispersive liquid-liquid microextraction using dicyclohexylamine

A combined method with dispersive liquid-liquid microextraction (DLLME) and electrothermal atomic absorption spectrometry (ETAAS) has been developed for determining gold(III). Dicyclohexylamine, a new extractant for gold(III), showed excellent performance in DLLME. Acetone was indispensable to the quantitative extraction of gold(III), contributing to decrease in hydration, decrease in the difference in the dielectric constants between the supernatant phase and the sedimented phase, and dissolution of a part of chloroform as an extraction solvent to the supernatant phase as well as improvement of dipersibility. In DLLME using a mixture of 1.0 mL of acetone and 100 μL of chloroform containing 50 mmol L⁻¹ of dicyclohexylamine, gold(III) could be extracted selectively and effectively from 8 mL of a sample solution in the presence of iron(III), cobalt(II), nickel(II), copper(II), palladium(II), and platinum(IV) at pH 1. The extracted gold(III) was determinable by ETAAS; the detection limit was 0.002 μg L⁻¹ (three times the standard deviation of the blank values, n = 8) as a gold(III) concentration in 8 mL of sample solution. The proposed method was applicable to the determination of gold in platinum metal and its alloy as well as effluent without any interference by the matrices.     

Spectrophotometric determination of palladium by solvent extraction as the Pd(II)-biacetylmonoxime 2-pyridylhydrazone complex

Determination of trace levels of palladium(II) is described. The method relies upon the extraction of palladium(II)-biacetylmonoxime 2-pyridylhydrazone (BMPH) from aqueous acidic solution into chloroform to form a purple-reddish complex. The molar absorptivity of the Pd-BMPH complex is about 7500 liters mol^?1 cm^?1 at 560 nm in the chloroform extract. The highly colored chloroform extract is suitable for spectrophotometric determination. The method devised has been applied to the determination of palladium in $\text{Pd}\text{CaCO}{}_3$ catalyst with good results.     

Extraction—spectrophotometric determination of palladium(ii) with 2-nitroso-5-diethylaminophenol

An extraction—spectrophotometric determination of palladium(II) with 2-nitroso-5-diethylaminophenol is described. Complex formation and extraction of the complex with chloroform are possible with aqueous phases of about 2.5 M sulfuric acid. The molar absorptivity of the complex is 4.38 X 10⁴ l mol^-1 cm^-1 at 486 nm. Few of the common ions interfere at concentrations of 10^-4–10^-3 M; more than 10^-5 M Ir(IV), 10^-5 M W(VI), 5 × 10^-6 M Au(III) and 10^-6 M iodide cause negative errors. The method can be applied to the determination of palladium in catalysts for automobile exhaust purifiers.     

Extraction of palladium from nitric acid medium by commercial resins with phosphinic acid,methylene thiol and isothiouronium moieties attached to polystyrene-divinylbenzene

Summary Commercially available polystyrene-divinylbenzene (PS-DVB) resins functionalized with isothiouronium (Tulsion CH-95), phosphinic acid (Tulsion CH-96) and methylene thiol (Tulsion CH-97) moieties have been used for separating palladium from nitric acid medium. Extraction of palladium has been studied as a function of time, concentration of nitric acid and palladium. The distribution coefficients (K_d, ml/g) of palladium on sulfur based resins (Tulsion CH-95 and Tulsion CH-97) are higher (5000-10⁴ml/g in 0.1M nitric acid) than on Tulsion CH-96 resin and decrease with increasing concentration of nitric acid. The initial rate of extraction of palladium by Tulsion CH-95 and Tulsion CH-97 resins was very rapid and the time required for the establishment of equilibrium was a function of palladium concentration in the aqueous phase. The rate data could be fitted by a second order rate equation and the magnitude of rate constant for the extraction of palladium by these resins (~10²M^-1. min^-1) decreased in the order of: Tulsion CH-95 > Tulsion CH-97 > Tulsion CH-96. The extraction isotherms of Tulsion CH-95 were fitted by Langmuir adsorption model and the coefficients were obtained by regression. The extraction capacity of palladium on Tulsion CH-95 was found to be ~20 mg/g at 3M nitric acid. Column experiments have been conducted and the data were fitted using Thomas model. A column utilization of 75% was achieved for the extraction of palladium by Tulsion CH-95 resin.