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.     

Kinetics of platinum(II) and platinum(IV) sorption from hydrochloric acid solutions with a complexing ion exchanger containing thiourea functional groups and with a strongly basic anion exchanger

The kinetics of platinum(II) and platinum(IV) sorption from 2 M HCl with Purolite S920 complexing ion exchanger containing thiourea functional groups and Purolite A500 strongly basic anion exchanger was studied in relation to the resin granule size, stirring intensity, and temperature.     

Synthesis of thiol chelating resins and their adsorption properties toward heavy metal ions

A series of chelating resins, derived from a macroreticular styrene-divinylbenzene (2%) copolymer beads grafted with various poly(ethylene glycols) HO? (? CH₂? CH₂? O? )_n? H(n = 0, 4, 9, 13) and containing thiol groups as chelating functions, have been synthesized in a three-step reaction sequence. The structure of the functionalized resins was confirmed by IR spectrophotometry, elemental analysis, and differential scanning calorimetry. The complexation behavior of these thiol resins was investigated towards Hg(II), Cu(II), and Pb(II) ions in aqueous solution by a batch equilibration technique. The influence of pH on adsorption capacity was also examined. The adsorption values for metal ions' intake followed the order Hg(II) > Cu(II) > Pb(II). The affinity of these polymers towards Hg(II) ions was so high that the total mercury level in the liquid decreased from 20 ppm to below 10 ppb after 2 h of treatment. Polymers can be regenerated by washing with a solution of hydrochloric acid (6N) and 10% by weight of an aqueous solution of thiourea. © 1994 John Wiley & Sons, Inc.     

Improved recovery of trace amounts of gold (III), palladium (II) and platinum (IV) from large amounts of associated base metals using anion-exchange resins

The adsorption and desorption behaviors of gold (III), palladium (II) and platinum (IV) were surveyed in column chromatographic systems consisting of one of the conventional anion-exchange resins of large ion-exchange capacity and dilute thiourea solutions. The noble metals were strongly adsorbed on the anion-exchange resins from dilute hydrochloric acid, while most base metals did not show any marked adsorbability. These facts made it possible to separate the noble metals from a large quantity of base metals such as Ag (I), Al (III), Co (II), Cu (II), ¶Fe (III), Mn (II), Ni (II), Pb (II), and Zn (II). Although it used to be very difficult to desorb the noble metals from the resins used, the difficulty was easily overcome by use of dilute thiourea solutions as an eluant. In the present study, as little as 1.00 μg of the respective noble metals was quantitatively separated and recovered from as much as ca. 10 mg of a number of metals on a small column by elution with a small amount of dilute thiourea solution. The present systems should be applicable to the separation, concentration and recovery of traces of the noble metals from a number of base metals coexisting in a more extended range of amounts and ratios.     

A polymer inclusion membrane based on the ionic liquid trihexyl(tetradecyl)phosphonium chloride and PVC for solid–liquid extraction of Zn(II) from hydrochloric acid solution

Abstract  

Extraction of Zn(II) from aqueous solution using polymer inclusion membranes based on poly(vinyl chloride) containing the phosphonium-based ionic liquid trihexyl(tetradecyl)phosphonium chloride (Cyphos^? IL 101) is described. Zn(II) could efficiently be extracted from 5 M hydrochloric acid solution with membranes containing 30 wt% Cyphos IL 101, whereas back-extraction was successfully achieved with 1 M sulfuric acid. Prepared membranes were evaluated in terms of stability in air as well as in terms of leaching of the ionic liquid from the membranes in aqueous solution.     

Sorption and preconcentration of some heavy metals by 2-mercaptobenzothiazole-clay

2-Mercaptobenzothiazole loaded on previously treated clay was prepared, characterized and used for sorption and preconcentration of Hg(II), Pb(II), Zn(II), Cd(II), Cu(II) and Mn(II) from an aqueous solution. The support used was a natural clay previously treated with sulphuric acid solution. Adsorption isotherms of metal ions from aqueous solutions as function of pH were studied at 298 K. Conditions for quantitative retention and elution were established for each metal by batch and column methods. The chemically treated clay was very selective to Hg(II) in solution in which Zn(II), Cd(II), Pb(II), Cu(II) and Mn(II) were also present.     

Application of an organic–inorganic hybrid membrane for selective gold(III) permeation

An organic–inorganic hybrid membrane was synthesized and evaluated for gold(III) transport from concentrated hydrochloric acid medium. The membrane was prepared by crosslinking of hydroxy terminated poly(dimethylsiloxane) with (3-aminopropyl) triethoxysilane in the presence of the commercial extractant Kelex 100. An optimization of the transport conditions was performed and selectivity with respect to copper(II) and zinc(II) determined. Around 70% of Au(III) was transported from an initially 10 ppm aqueous solution under optimized conditions with high selectivity towards 50 ppm of Cu(II) or 100 ppm of Zn(II) in 6 h. In addition the membrane extraction equilibrium reaction and its corresponding extraction equilibrium constant were evaluated and compared to those obtained in liquid–liquid solvent extraction. Membrane characterization was attained by ATR-FTIR spectroscopy.     

配位滴定法连续测定铜和锌的新指示剂

对2-（3,5-二氨-2-吡啶偶氮）-5-二甲基苯胺（3,5-diCl-PADMAB）作指示剂络合滴定铜和锌进行了研究。在pH5．0的乙酸-乙酸钠介质中,以3,5-diCl-PADAMAB作指示剂,EDTA为滴定剂连续测定铜和锌,滴定终点颜色变化敏锐,准确度高,铜和锌量各在0～20mg范围内与EDTA量成正比。方法用于合金中铜和锌的测定,分析结果的相对标准偏差为〈0．1％和〈0．4％。     

Synthesis and physicochemical properties of 1-(2-alkylamidoethyl)-2-alkyl-2-imidazolines based on α,α′-branched carboxylic acids

Condensation of diethylenetriamine with lauric, 2-ethylhexanoic, and α,α′-branched C_10,12-carboxylic acids results in 1-(2-alkylamidoethyl)-2-alkyl-2-imidazolines. A stability of the synthesized compounds relative to the acid and alkaline hydrolysis was studied. Their protonation constants were determined. The effect of the structure of the alkyl substituents on the distribution of the substance between the organic and aqueous phases was examined. The principal possibility of extracting Zn(II), Fe(III), Cu(II), Co(II), Mn(II) chlorides from hydrochloric acid solutions was shown. A mixture of 1-(2-alkylamidoethyl)-2-alkyl-2-imidazolines based on the α,α′-branched carboxylic acids was suggested as a potential extractant of the metal salts from hydrochloric acid and chloride solutions.     

Selective Transport of Copper(II) Ion across a Polymer Membrane Incorporating a Difunctional Schiff-base Ionophore

The selective polymer membrane transport of Cu(II) from an aqueous solution containing seven metal cations, Co(II), Ni(II), Cu(II), Zn(II), Ag(II), Cd(II) and Pb(II), was studied .The source phase contained equimolar concentrations of the above-mentioned cations, with the source and receiving phases being buffered at pH 4.9 and 3.0, respectively. Cu(II) ion transport occurred (J=2.82 × 10⁻⁷ mol/h at 25 °C) from the aqueous source phase across the polymer membrane (derived from cellulose triacetate) containing ligand (I) as the ionophore, into the aqueous receiving phase. Clear transport selectivity for Cu(II) was observed.     

Facilitated transport of palladium(II) across polymer inclusion membrane with ammonium ionic liquid as effective carrier

This work focuses on the application of polymer inclusion membrane (PIM) with tricaprylmethylammonium thiosalicylate, [A336][TS] (TOMATS), a thiol-containing task-specific ionic liquid for the transport of Pd(II) ions from aqueous solutions. 0.3 M thiourea in 0.1 M hydrochloric acid was found the most effective stripping phase in the transport of Pd(II) from membrane phase containing TOMATS. Separation of Pd(II) ions was also carried out from hydrochloric acid solution containing Pt(IV), Fe(III), Ni(II), and Mn(II). Pd(II) ions were preferably transported in the presence of these metal ions. The separation coefficients followed the order: S _Pd/Pt < S _Pd/Fe < S _Pd/Ni < S _Pd/Mn. [A336][TS] proved to be an excellent ion carrier for Pd(II) from hydrochloric acid solution. The results also showed that transport efficiency of the PIM was reproducible and it can be useful for the development of the simple and highly effective method of Pd(II) recovery from leach liquor of spent catalysts.     

Separation of traces of heavy metals from an iron matrix by use of an emulsion liquid membrane

An emulsion liquid membrane method has been developed for separating traces of heavy metals from an iron matrix. A 1.0-mL volume of aqueous iron(III) solution (pH 2.0) was emulsified with a mixture of 0.6 mL toluene, 2.4 mL n -heptane, and 80 mg sorbitan monooleate (Span-80). The resulting water-in-oil type emulsion was gradually injected into 25 mL of 1.5 mol L^–1 hydrochloric acid solution containing 30 mmol L^–1 8-quinolinol and 1.0 mol L^–1 of ammonium sulfate and was dispersed as numerous tiny globules by stirring for 40 min. More than 90% of the iron(III) diffused through the oil layer to the external hydrochloric acid solution with the aid of complexation with 8-quinolinol, whereas trace heavy metals, e.g. Cr(III), Mn(II), Co(II), Ni(II), Cu(II), and Pb(II), remained quantitatively in the internal aqueous phase. After collecting the dispersed emulsion globules, they were demulsified and trace metals in the segregated aqueous phase were determined by graphite-furnace atomic absorption spectrometry. Owing to sufficient removal of the iron matrix trace metal impurities in high-purity iron were successfully determined without interference, as was confirmed by analysis of certified reference materials.     

Improved recovery of trace amounts of gold (III), palladium (II) and platinum (IV) from large amounts of associated base metals using anion-exchange resins

The adsorption and desorption behaviors of gold (III), palladium (II) and platinum (IV) were surveyed in column chromatographic systems consisting of one of the conventional anion-exchange resins of large ion-exchange capacity and dilute thiourea solutions. The noble metals were strongly adsorbed on the anion-exchange resins from dilute hydrochloric acid, while most base metals did not show any marked adsorbability. These facts made it possible to separate the noble metals from a large quantity of base metals such as Ag (I), Al (III), Co (II), Cu (II), Fe (III), Mn (II), Ni (II), Pb (II), and Zn (II). Although it used to be very difficult to desorb the noble metals from the resins used, the difficulty was easily overcome by use of dilute thiourea solutions as an eluant. In the present study, as little as 1.00 microg of the respective noble metals was quantitatively separated and recovered from as much as ca. 10 mg of a number of metals on a small column by elution with a small amount of dilute thiourea solution. The present systems should be applicable to the separation, concentration and recovery of traces of the noble metals from a number of base metals coexisting in a more extended range of amounts and ratios.     

Ion-exchange behaviour of metals on deae-cellulose in methanol-thiocyanate-hydrochloric acid media

Only a few metals can be adsorbed on DEAE-cellulose from aqueous thiocyanate-chloride media. However, several metal ions, including Cu(II), Zn, Cd, In, Bi and U(VI), exhibit enhanced adsorption on DEAE-cellulose from methanol-thiocyanate-hydrochloric acid mixtures. The distribution coefficients for these metals are given as functions of methanol, ammonium thiocyanate and hydrochloric add concentration. Differences in adsorption among metals permit many useful separations, including those of two-, three- and four-component mixtures, on short columns containing 1-1.5 g of DEAE-cellulose.     

Extractive separation of molybdenum as Mo(V) xanthate from Iron, vanadium, Tungsten, copper, uranium and other elements

A simple and selective extraction of molybdenum is described. Tungsten is masked with tartaric acid and molybdenum(VI) is reduced in 2M hydrochloric acid by boiling with hydrazine sulphate. Iron, copper and vanadium are then masked with ascorbic acid, thiourea and potassium hydrogen fluoride respectively. The molybdenum(V) is extracted as its xanthate complex into chloroform, from 1M hydrochloric acid that is 0.4M potassium ethyl xanthate. The complex is decomposed by excess of liquid bromine, and the molybdenum is stripped into alkaline hydrogen peroxide solution. The molybdenum is then determined by standard methods. Large amounts of Cu(II), Mn(II), Fe(III), Ti(IV), Zr, Ce(IV), V(V), Nb, Cr(VI), W(VI), U(VI), Re(VII) and Os(VIII) do not interfere. Several synthetic samples and ferromolybdenum have been rapidly and satisfactorily analysed by the method.     

Sorption behaviour of lanthanum(III), neodymium(III), terbium(III), thorium(IV) and uranium(VI) on Amberlite XAD-4 resin functionalized with bicine ligands

The complexing properties (capacity, pH effect, breakthrough curve) of a chelating resin, containing bicine ligands, were investigated for La(III), Nd(III), Tb(III), Th(IV) and U(VI). Trace amounts of these metal ions were quantitatively retained on the resin and recovered by eluting with 1 M hydrochloric acid. The capacity of the resin for La(III), Nd(III), Tb(III), Th(IV) and U(VI) was found to be 0.35, 0.40, 0.42, 0.25 and 0.38 mmol g(-1), respectively. Separation of U(VI) and Th(IV) from Ni(II), Zn(II), Co(II) and Cu(II) in a synthetic solution was carried out.     

Liquid Extraction of Noble Metal Ions with an α-Amino Phosphonate

The extraction of Au(III), Pt(IV), and Pd(II) ions from aqueous hydrochloric acid solutions with solutions of bis(2-ethylhexyl) N-butyl-N-octylaminomethylphosphonate in chloroform and xylene was studied. The recovery of the noble metal ions is the most efficient at low acidities of the aqueous solution, with a high selectivity of separation from the concomitant Fe(III), Cu(II), Ni(II), and Co(II) ions.     

Sorption of Heavy Metals from Model Solutions with Amine-Containing Chemisorption Polyamide Fiber

Sorption of Cu(II), Ni(II), Zn(II), and Cr(VI) ions with POLAN-OG sorbent was studied. The capacity and kinetic characteristics of the sorbent in hydrochloric acid and chloride solutions were determined.     

Anodisation of copper in thiourea- and formamidine disulphide-containing acid solution.: Part I. Identification of products and reaction pathway

The anodic behaviour of copper in aqueous 0.5 M sulphuric acid containing different amounts of dissolved thiourea or formamidine disulphide was investigated at 298 K, combining data from electrochemical polarisation, chemical analysis, UV–vis spectroscopy, XPS and EDAX analysis, and structural information on copper–thiourea complexes. The main reactions depend on the applied potential and initial thiourea concentration. In the potential range −0.30≤E≤0.075 V (versus SCE), the electro-oxidation of thiourea to formamidine disulphide, the formation of Cu(I)–thiourea soluble complexes, and Cu(I)–thiourea complex polymer-like films, are the most relevant processes. The formation of this film depends on certain critical thiourea/copper ion molar concentration ratios at the reaction interface. At low positive potentials, the former reaction is under intermediate kinetic control, with the diffusion of thiourea from the solution playing a key role. For E≥0.075 V, soluble Cu(II) ions in the solution are formed and the anodic film is gradually changed to another one consisting of copper sulphide and residual copper. The new film assists the localised electrodissolution of copper. A complex reaction pathway for copper anodisation in these media for the low and high potential range is advanced.     

The quantitative separation of calcium from magnesium,aluminium and other elements by cation-exchange chromatography in ethanol-hydrochloric acid

Magnesium can be separated from calcium by elution with 3.0 M hydrochloric acid containing 60% ethanol from a column of AG₅₀W-X8 cation-exchange resin. Calcium is retained and can be eluted with 3.0 M hydrochloric acid or 2.0 M nitric acid. The separation factor of (α_Mg^ca=5.6 is considerably higher than that in aqueous hydrochloric acid and comparable to those obtained with organic complexing reagents. Separations are sharp and quantitative; up to 10 mmol of magnesium can be separated from 0.01 mmol of calcium and vice versa on a 60-ml column. Al, Fe(III), Mn, Ni(II), Co(II), Zn, Cd, Cu(II), Pb(II), U(VI), Be, Ga, Ti(IV) in the presence of H₂O₂ and many other elements accompany magnesium and can be separated from calcium quantitatively. Sr, Ba, Zr, Hf, Th, Sc, La and the rare earths are retained together with Ca, but can be separated by other methods.