Quantitative analysis by electro-chromatography on paper : The separation and gravimetric determination of copper

Up to 20 mg of copper can be quantitatively separated from small quantities of gold, platinum and palladium, by ionophoresis on strips of paper pulp, 6 mm thick, 25 mm wide and 250 mm long. One millilitre of the hydrochloric acid solution of the metallic salts is placed on the paper, the ends of which are placed in cells containing 50 ml N HC1 and 25 ml N KC1. The paper is then moistened with N HC1. Carbon electrodes are used and are connected to a 12 volt D.C. supply, a current of about 200 milliamperes being recorded. The copper travels towards the cathode and after about 18 hours separates completely from the noble metals as a blue band about 75 mm in length. This band is cut out and used for the determination of the copper by electrodeposition, after decomposition of the organic matter by means of concentrated nitric and sulphuric acids.     

The extraction of niobium (V) and Tantalum (V) by Octylarsinic acid in chloroform

Dioctylarsinic acid (HDOAA) in chloroform solution extracts Nb(V) and Ta(V) efficiently from solutions containing oxalate and oxalic acid at hydrochloric acid concentrations greater than 1M.The extraction coefficients are 92.5 at 7M hydrochloric acid and 251 at 6M hydrochloric acid for niobium and tantalum, respectively. These metals can be extracted even more efficiently from sulfuric acid solutions. The results of the reagent- and pH-dependence studies suggested that a trimeric, monobasic oxoacid of niobium, associated with ten HDOAA molecules, is extracted. Tantalum appears to be present in the organic phase as (H₂DOAA)⁺ [Ta(C₂O₄)₃ (HDOAA_n] (n=l or 2).     

Ion exchange resins in steel analysis

The metals vanadium, chromium and molybdenum may be separated from the other constituents of steel by passing an acetate buffered solution of the steel through a strongly basic onion exchanger and selectively eluting the above metals from the resin column with aqueous solutions of 0.6 N sodium hydroxide, 8 N hydrochloric acid and 1 N hydrochloric acid, respectively.     

Solvent extraction of lead,silver, antimony and thallium with zinc dibenzyldithiocarbamate and its application to the separation of bismuth from large amounts of lead

Solvent extraction of lead, silver, antimony and thallium from various acid solutions was investigated with zinc-DBDTC as chelating reagent. These metals were quantitatively extracted over a wide range of acidity with 0.03% zinc-DBDTC solution in carbon tetrachloride. A separation procedure for bismuth from large amounts of lead was developed; bismuth was extracted from 1 M nitric acid with zinc-DBDTC and was separated from lead by subsequently washing the organic phase once with 3.5 M hydrochloric acid or twice with 3 M hydrochloric acid. Satisfactory results were obtained in separating microgram amounts of bismuth from 1 g of lead.     

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.     

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.     

Recycling of Palladium and Selected Metal Ions from Simulated Spent Catalysis Waste Solution Using Novel Dithiodiglycolamides Derivatives

The present study focusing on design and evaluation of series of eight new structurally related dithiodiglycolamides (DTDGA) as a novel promising solvent extraction reagents. The influence of the nature of the alkyl chain on the distribution ratio of Pd(II) was investigated. Both N, N-di-hexyl-N′, N′-di-octyldithiodiglycolamide (DHDODTDGA) and N, N-di(2-ethylhexyl)-N′, N′-dioctyldithiodiglycolamide (DEHDODTDGA) were chosen and applied to perform the selective recovery and separation of Pd(II) from certain commonly associated elements such as Pt(IV), Rh(III), Fe(III), Cr(II), Mn(II), Zr(II), and Ni(II) contained in hydrochloric acid solutions using n-dodecane as diluent. A systematic investigation has been carried to understand the extraction behavior of Pd(II) using the synthesized extradant. The extraction equilibrium of Pd(II) was obtained within 3–4 min. The investigated extractants showed quantitative extraction of Pd(II) at ～ 4 M HCl. The main extracted species of Pd(II) at 3.5 M HCl is Pd.DTDGA and IR spectra of the extracted species have been also studied. The other investigated metals ions were found poorly extracted under the same extraction contortions. Quantitative back-extraction of Pd(II) in the organic phase was obtained in single contact using thiourea solution. The obtained results make the novel synthesized ligands a promising candidates for selective recovery and separation of Pd(II) from spent catalyst dissolver (SSCD) solution.

     

Elektrophorese der halogenokomplexe von Hg(II), Bi(III), Cd(II), Pb(II) und -Cu(II) : Chlorokomplexe in chlorwasserstoffsäure

An apparatus for heavy-current and high-tension electrophoresis on filter paper is described This apparatus enables one to avoid the difficulties that occur in electrophoresis in base electrolytes that are highly concentrated or show greater electric conductivity The zones migrate along the paper strips with constant speed and, consequently, it is possible to measure the mobility The effective length of the filter paper strips is 660 mm Correction of the apparent mobility in the porous adsorbent is treated thoroughly.Diagrams of the electrophoretic mobility of the chloro-complexes of Hg(II), Bi(III), Cd(II), Pb(II), and Cu(II) in hydrochloric acid, are given in the experimental part The concentration of the hydrochloric acid varied between 0.1N and 6N In 6N HCl all the metals investigated are present asani onic complexes. Hg, Bi.Cd, and Pb chloro-complexes show a pronounced maximum of mobility in the anionic range. The sequence of the zones in the direction anode to cathode is Hg, B1, Cd, Pb, Lu al 0.1–2.3N HCl and B1, Hg, Cd, Pb.Cu at2.3–6N HCl.Finally, the electrophoretic separation of a mixture of Hg, Bi, Cd, Pb, Cu in 1N, 2N and 4N HCl is illustrated Complete separation of the zones was achieved in each experiment     

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.     

Vanadium(V) extraction from sulfuric and hydrochloric acid solutions with hydrazides and <Emphasis Type="Italic">N</Emphasis>′,<Emphasis Type="Italic">N</Emphasis>′-dialkylhydrazides of Versatic acids

Conditions of vanadium(V) extraction from sulfuric and hydrochloric acid solutions with kerosene solutions of hydrazides and N’,N’-dimethylhydrazides derived from fractions of Versatic 10 and Versatic 1519 branched higher carboxylic acids were studied. Conditions of vanadium(V) back extraction from organic phase were studied. For diluted acid solutions, ratios were found to be [V(V)]: [reagent] = 1: 1 and 1: 5 for sulfuric acid media and 1: 1 and 1: 8 for hydrochloric acid media.     

New spectrophotometric thiocyanate determination of iron in metals,alloys, acids and salts

A rapid, sensitive and fairly selective spectrophotometric thiocyanate method for the determination of traces of iron in metals, alloys, acids and salts is described. The iron is isolated from the bulk of the sample by solvent extraction with methyl isobutyl ketone from ₇N lithium chloride solution or ₇N hydrochloric acid. The iron (III) thiocyanate color is developed directly in the ketone extract and then measured spectrophotometrically.     

Preconcentration and separation of copper (II) with solvent extraction using N,N′-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane

Preconcentration and separation with solvent extraction of Cu(II) from aqueous solution using N,N′-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane (H₂L) as the new extractant has been studied. Separation of Cu(II) from other metal ions such as Cd(II), Ni(II), Zn(II), Pb(II), Cr(III), Co(II) and Mn(II) at aqueous solutions of various pH values and complexing agent H₂L, has been described. The possible extraction mechanism and the compositions of the extracted species have been determined. The separation factors for these metals using this reagent are reported while efficient methods for the separation of Cu(II) from other metal ions are proposed. From the loaded organic phase, Cu(II) stripping was carried out in one stage with different mineral acid solutions. The stripping efficiency was found to be quantitative in case of HNO₃ and HCl. From quantitative evaluation of the extraction equilibrium data, it has been deduced that the complex extracted is the simple 1:1 chelate, CuL. The extraction constant has a value of logK_ex=−4.05±0.04.     

Extraction of zinc with tri(iso-octyl)amine in methyl isobutyl ketone and colorimetric determination with zincon in the organic phase

A study was made of the extraction of zinc from hydrochloric acid solutions with solutions of methyldioctylamine and tri(iso-octyl)amine in methyl isobutyl ketone. Quantitative extraction was accomplished from 2 N hydrochloric acid with 5% (w/v) tri(iso-octyl)amine-methyl isobutyl ketone. A procedure was developed for the colorimetric determination of zinc in the organic phase after extraction using 2-carboxy-2'-hydroxy-5'-sulfoformazylbenzene (Zincon).     

Propiconazole and Penconazole as Effective Extractants for Selective recovery and concentration of platinum(IV) and palladium(II) from hydrochloric acid solutions formed in leaching of spent aluminoplatinum and aluminopalladium catalysts

Selective recovery and concentration of platinum(IV) and palladium(II) from hydrochloric acid solutions of varied composition was studied using commercial reagents propiconazole and penconazole as extractants. The ranges of hydrochloric acid concentrations for effective extraction and highly selective separation of platinum metals from Al(III) and Ni(II) with propiconazole (toluene with 15 vol % n-decanol as deluent) and penconazole (chloroform) were determined. The conditions for 10-fold selective concentration of platinum metals with recovery of more than 99.9% of metal ions into the organic phase were found. The conditions for quantitative (>99%) stripping of platinum(IV) with a hydrochloric acid solution of thiourea and palladium(II) with ammonia solution were determined. The results obtained can be used for optimizing the modes of selective recovery of platinum(IV) and palladium(II) from hydrochloric acid solutions formed in leaching of alumina-supported platinum-rhenium, platinum-nickel, and palladium catalysts.     

Direct spectrophotometric determination of indium in tin

Indium is separated from tin by an anion-exchange process in 0.5 M hydrochloric acid solution. Subsequently, the indium is extracted into 1,2-dichlorobenzene as its complex with 5,7-dichloro-8-quinolinol. The complex forms and extracts quantitatively in the pH range 3–7. The yellow, organic phase is measured spectrophotometrically at 415 mμ; ; its absorbancy is directly proportional to the indium content of the aqueous phase up to a total of 1.5 mg of indium per 50 ml. This procedure quantitatively separates the two metals, allows one to determine the indium content of indium(<5%)-tin alloys with a relative error less than 0.7%, and considerably reduces color fading errors inherent in some previously reported spectrophotometric methods for indium.     

Elektrophorese der halogenokomplexe von Hg(II), Bi(III), Cd(II), Pb(II) und Cu(II): Abhängigkeit der beweglichkeiten von der konzentration des metallions

The dependence was investigated of the mobilities of the chloro-complexes of Hg(II), Cd(II), Pb(II) and Cu(II) on the concentration and the volume of the metal salt solution applied, the experiments being carried out in relatively low concentrations of hydrochloric acid (0.1N, 0.5N and 1N) This dependence is considerable in base clectrolytes of low concentration (Iess than 1N HCl) and insignificant in the case of higher concentrations (greater than 1N HCl)On increasing the concentration and volume of the metal salt applied, the Caitionic mobility of the zones increases and the amonic mobility decreasesUnder certain conditions chloro-, bromo-, and lodo-complcxcs of cadmium showed multispots Wc have occasionally obbcived these multispotsalsom the cicctrophorcsis of other metal complcKCb     

Single-step radiochemical separations by column procedures in activation analysis

Some single-step column procedures are described for both individual and group activity separations. Besides the usual ion-exchange techniques, other methods such as reverse-phase chromatography, isotopic exchange and the use of resins converted into special forms were used. Fast and simple selective separations from 2N hydrochloric acid are reported for Mo(VI), Cu(II), Sb(V), and for AsO₄^3- + PO₄^3- from both 2 N hydrochloric acid and I N sulfuric acid; for Cu, Sb and As + P, the selectivity can be greatly increased by using a guard bed of resin in normal form. By combining the different techniques a single-step separation scheme for 6 elements (Mo, Au, Zn, As, Cu, Sb) in 2 N hydrochloric acid was developed; this allows high chemical recoveries, high cross-decontamination and very large decontamination from ²⁴Na to be reached, so that application for biological sample analysis can be envisaged. Simplified two-stage column separations for Au + Sb and Cu and Fe + Sb and Zn from concentrated hydrochloric acid (cationic and anionic resin beds coupled) are also reported.     

The separation of mercury from gold by ion exchange

Mixtures containing large amounts of gold and small amounts of mercury (50:1) can be quantitatively separated by passing a 2N hydrochloric acid solution of the chlorides through Dowex 50 resin. Mercury behaves as a cation and is quantitatively retained. Gold behaves as an union and is not retained by the resin. The gold is obtained spcctrobcopically free from all metals. The capacity of the resin is approximately 10 nig of mercury per gram of rebin. The rcyin is freed from mercury by washing with 2N liydroclonc acid and may be used over again.     

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.     

Synthesis, characterization and some properties of epoxy resins containing azomethine bonding

New epoxy resins were prepared from hydroxyl substituted Schiff base monomers in two steps. The first step is based on the synthesis of hydroxyl substituted Schiff base monomers via condensation reaction. The second step includes the reaction between Schiff base monomers with epichlorohydrine (EPC) to obtain epoxy resins. The structures of resulting compounds were confirmed by FTIR and ¹H-NMR. TG-DTA and DSC measurements were made for thermal characterizations of the compounds. Chemical resistances of the cured epoxy-amine systems in acidic, alkaline and organic solvents were determined for coating applications. HCl (aqueous solution, 10%), NaOH (aqueous solution, 10%), DMSO, DMF, N-methylpyrrolidone, ethanol, THF and acetone were used for corrosion tests. Chemical resistance data show that the synthesized resins have good chemical resistance against various acid, alkaline and common organic solvents.