Ion-exchange recovery of nickel(II) and cobalt(II) from sulfuric acid solutions

Sorption recovery of nickel(II) and cobalt(II) in their joint presence in sulfuric acid solutions was studied on new samples of domestic ion exchangers of CYBBER brand. It was shown that the ion exchangers under study have a high sorption capacity for ions of both nonferrous metals, depending on the structure of a sorbent and on the acidity of a contacting solution. It was found that, after Co(II) and Ni(II) ions are extracted from weak or strong sulfuric acid solutions, they can be effectively eluted from the ion exchangers under study with a 2 M hydrochloric acid solution to an extent of 85–95% (nickel) and 87–95% (cobalt).     

Ion-exchange sorption of silver(I) chloride complexes from aqueous HCl solutions

The ion-exchange sorption of silver(I) chloride complexes from 1–4 M aqueous solutions of HCl on a series of Purolite anionites with various functional groups was studied. The ion-exchange equilibria in the systems were found to be anomalous according to Raman spectroscopy, which does not significantly affect the sorption properties of the ionites.     

Low-temperature equilibriums in solutions of isocyanide-phosphine complexes of palladium(II) chloride

cis-[PdCl₂(CNR)(PPh₃)] [R = Cy, t-Bu, C(Me)₂CH₂C(Me)₃] have been synthesized via the interaction of [(PPh₃)ClPd(μ-Cl)₂PdCl(PPh₃)] with isocyanide in CH₂Cl₂ at room temperature with 90–98% yield and characterized by means of mass spectrometry as well as ¹H, ¹³C{¹H, ³¹P}, and ³¹P{¹H} NMR spectroscopy. The complexes structure in the solid phase has been elucidated by means of X-ray diffraction analysis. Dynamic processes in the solutions of the complexes in CDCl₃ and CD₂Cl₂ at temperature of–95 to 60°С have been studied by means of ¹H and ³¹P NMR spectroscopy. It has been found that the studied compounds existed exclusively in the cis-[PdCl₂(CNR)(PPh₃)] form in the solutions. In the case of cis-[PdCl₂(CNCy)(PPh₃)] in CH₂Cl₂, the conformational transitions of the equilibrium forms (the transition of the substituent in the cyclohexyl cycle between the equatorial and axial positions) are slowed down, the equatorial conformer prevailing in the solution (2: 1 at–95°С). Quantum-chemical simulation (DFT) has revealed that the standard Gibbs energy of the conformational transition from the axial form of cis-[PdCl₂(CNCy)(PPh₃)] into the equatorial one in the CH₂Cl₂ solution at 178 K equals–2.5 kJ/mol, being in agreement with the experimental data.     

Sorption recovery of platinum(II, IV) from chloride and sulfate-chloride solutions

Sorption of platinum(II, IV) from chloride and sulfate-chloride solution on anion exchangers of varied chemical structure (various functional groups and varied basicity) was studied. It was found that sulfate-chloride systems have high efficiency comparable with that of chloride systems in sorption of platinum by AM-2B, Purolite S 985, and Lewatit MP 600 WS anion exchangers.     

Ion-exchange recovery of nickel(II) from wash water formed in electroless plating in acid hypophosphite solutions

Kinetic aspects of extraction of Ni(II) ions with KU-2–8 cation-exchange resin in the Na⁺ form from wash water produced in electroless nickel-plating were studied. The optimal conditions and parameters of ion-exchange purification and regeneration of the cation-exchanger were determined.     

Sorption recovery of rhodium(III) from chloride and chloride-sulfide solutions

Sorption of rhodium(III) from chloride and chloride-sulfate solutions on anion exchangers of varied physical and chemical structure was studied.     

Extraction of palladium(II) from hydrochloric acid solutions with triacylated ethyleneamines

Extraction of palladium(II) from hydrochloric acid solutions with novel efficient extractants, triacylated ethyleneamines, was studied. The most effective extraction of palladium(II) was observed from 0.5–1 M HCl solutions. Extraction of palladium(II) from 1 M HCl solutions was found to occur through mixed (coordination and anion-exchange) mechanism. In the field of dominance of the anion-exchange mechanism of the extraction of palladium(II) with triacylated pentaethylenehexamine the concentration constant of palladium(II) extraction was calculated, and thermodynamic parameters of extraction were evaluated.     

Orthometalation reactions of substituted benzylideneamines by palladium(II) chloride

Carbonmetal σ-bonded complexes have been synthesized by reaction of various substituted benzylideneamines with PdCl₂. The chloro-bridged complexes formed have been studied by spectroscopic methods and by thermogravimetric analyses.     

Ion exchange extraction of platinum(IV) and palladium(II) from hydrochloric acid solutions

Sorption concentration of platinum(II, IV) and palladium(II) from freshly prepared and aged two-yearold hydrochloric acid solutions by a series of anion exchangers with different functional groups and of different physical structure of Purolite and CYBBER grades was studied. The high sorption ability of the ion exchangers in relation to the extracted chlorocomplexes of noble metals is shown. It was demonstrated that palladium(II) from all tested ion exchangers can be completely desorbed with thiourea solutions acidified with hydrochloric acid, while complete desorption of platinum is achieved only from Purolite S 985 anion exchanger of the complexforming type and Purolite A 111 weak base anion exchanger.     

Extraction of copper(II) from ammonium chloride solutions with capric acid

Extraction of copper(II) with capric acid from ammonium chloride solutions was examined. The composition of the complex extracted was determined and it was found that the extraction process can be adequately described by the equation: 2Cu_(a)²⁺ + 3(HR)_2,(0) ⇌ (CuR₂·HR)_2,(0) + 4H_(a)⁺     

Sorption of palladium(II) chloride complexes by nitrogen-containing modified shungites

The sorption properties of anion exchangers based on modified shungites with respect to palladium(II) ions from chloride solutions were studied. The effect of sorbent nature, pH of a solution, and process duration on the degree of their recovery was considered.     

Radiochemical extraction of mercury(II) from acidic chloride solutions using dialkylsulphides

The liquid-liquid extraction behavior of Hg(II) from aqueous acidic chloride solutions has been investigated by tracer techniques using dialkylsulphides (R₂S) namely, dibutylsulphide (DBS) and dioctylsulphide (DOS) as extractants. These extraction data have been analyzed by both graphical and theoretical methods by taking into account complexation of the metal ion in the aqueous phase with inorganic ligands and all plausible complexes extracted into the organic phase. The results clearly indicate that Hg(II) is extracted into xylene as HgCl₂ ^. nDBS/nDOS (where n = 2 and 3). The equilibrium constants of the extracted complexes have been deduced by non-linear regression analysis. The separation possibilities of Hg(II) from other metal ions viz. Ca(II), Mg(II), Ba(II) and Fe((III), which are present in the industrial wastes of the chlor-alkali industry has also been discussed.     

Complexes of dichloro(ethylenediamine)palladium(II) observed from aqueous solutions by electrospray mass spectrometry

Aqueous solutions of dichloro(ethylenediamine)palladium(II) were investigated using electrospray mass spectrometry (ESMS). The most abundant peak (m/z 436.8) was attributed to the dimeric Pd(en)Cl2.Pd(en)Cl+ ion. We conjecture that the structures of the observed ions arise from the clustering of the hydrolysis products of the parent compound. This hypothesis was tested experimentally by carrying out a series of collision-induced dissociation (CID) experiments and deuterium exchange reactions. It was also assessed by performing density functional theory (DFT) calculations, from which optimized structures and reaction energetics were obtained. These results were compared with our earlier ESMS study of an aqueous Pd(en)Br2 solution. Calculations were also carried out on the Pd(en)Br2 system to facilitate the comparisons. Conclusions are drawn regarding the species present in the two aqueous solutions.     

Extraction of palladium with tri-isobutylphosphine sulphide (cyanex 471) in toluene from chloride solutions containing thiocyanate

The extraction of PD(II) by tri-isobutylphosphine sulphide, TIBPS (Cyanex 47 1x), in toluene from aqueous chloride solutions (containing small amounts of thiocyanate) has been investigated. The extraction is enhanced by the presence of thiocyanate, owing to formation of mixed-ligand Pd(II)-Cl(-)-SCN(-)-TIBPS complexes. Analysis of the metal distribution suggests the formation of PdCl(SCN).TIBPS, PdCl(SCN).2TIBPS, Pd(SCN)(2).TIBPS and Pd(SCN)(2).2TIBPS in the organic phase. The equilibrium constants are logK(111) =9.56, logK(112) =12.70, logK(121) =14.73 and logK(122) =17.17, respectively. The ultraviolet absorption spectra of the organic phase support the hypothesis of formation of mixed-ligand complexes.     

Ion exchange recovery of chromium (VI) and manganese (II) from aqueous solutions

Sorption recovery of toxic ions – chromium (VI) and manganese (II) – from aqueous solutions with different acidity (0.001–0.5 M HCl) was investigated on cation and anion exchangers synthesized with long-chained cross-linking agents (LCA). The initial concentrations of Cr(VI) and Mn(II) were 1 g/L and 5 g/L, respectively. It was shown that the resins with LCA possess high ionic permeability due to the elasticity of polymeric skeleton. High selectivity and good kinetic properties of these sorbents allowed to achieve quantitative (∼100%) recovery and separation of manganese (II) and chromium (VI) in counter-current columns, which results in the complete purification of solutions from toxicants (below the maximum permissible limits), whereas the valuable components (chromium and manganese) can be returned back to industrial process.     

Electroreduction kinetics and mechanism of palladium(II) glycinate chloride complexes on rotating palladium disk electrode

The electroreduction kinetics of Pd(Hgly)₂Cl₂ on rotating palladium disk electrode was studied by means of cyclic voltammetry. The double layer range of the palladium charging curve showed a single wave with the diffusion limited current I _d, which yielded the diffusion coefficient of Pd(Hgly)₂Cl₂ complex D = 6 × 10⁻⁶ cm²/s. The plotted direct and reverse voltammetric curves were linearized in coordinates E, log[I/(I _d − I)]. The slope of this line gave b _k factor evidencing the slow electrochemical step. When [Cl⁻] decreased from 1 to 0.2 M, E _1/2 potential shifted to positive values. This was accounted for by reversible cleavage of Cl⁻ ion from Pd(Hgly)₂Cl₂ complexes before the irreversible electrochemical step. The pulse galvanostatic experiment resulted in the double electrical layer capacity and roughness factors f of electrolytic palladium deposits. The calculated values of f from 60 to 310 were attributed to adsorption of glycine particles on the electrodeposited palladium surface, which promotes to increasing number of palladium microcrystal growing centers.     

Manganese(II) extraction from chloride nickel solutions with the use of trioctylamine

The influence of the nature of a modificator added to an extraction mixture containing trioctylamine, of the chloride supporting solution concentration, and of temperatures on the manganese(II) extraction from chloride nickel solutions was studied. The composition of an extracted complex was determined. The possibility of using trioctylamine with a 2-octanone addition for deep cleaning of manganese(II) from chloride nickel solutions was shown.