Reversed-phase extraction chromatography of Germanium(IV) with tributyl phosphate on silica gel

Germanium(IV) can be separated by reversed-phase extraction chromatography with TBP as stationary phase on a column of silica gel, with 6M hydrochloric acid as the mobile phase, and stripped with various eluents. Germanium can thus be separated (by selective extraction) from those elements which are not extractable with TBP, and (by selective stripping) from elements that are extractable.     

Kinetics of iron(III) chloride extraction with n-tributyl phosphate

The equilibrium and rate of solvent extraction of FeCl₃ complexes from HCl solutions into benzene solutions of tributyl phosphate (TBP) has been studied. The extracted species was found to be FeCl₃·3TBP. The results show that the extraction is first order in both Fe(III) and TBP. The rate constant of adduct formation equals ～1.24M min^?1. The reaction order is zero for the aqueous phase acidity. The rate-controlling steps are discussed in the light of the results.     

Kinetics of iron(III) bromide extraction with n-tributyl phosphate

The equilibrium and rate of solvent extraction of FeBr₂ complexes from HBr solutions into benzene solutions of tributyl phosphate (TBP) have been investigated. It is found that two reactions control the iron(III)-TBP extraction from hydrobromic acid solutions. From HBr activity of 1.2–1.55 (molarity based) the reaction is inverse third order with respect to the aqueous phase acidity. From HBr activity of 1.7–6 (molarity based) the reaction is first order in HBr concentration in the aqueous phase. Both of these reactions are first order for both Fe(III) and TBP. The rate constants for these reactions were calculated and the rate-controlling steps are discussed.     

Synergistic extraction of uranium(VI) with tri-n-butyl phosphate and i-butyldodecylsulfoxide

Summary The synergistic extraction of uranium(VI) from aqueous nitric acid solution with a mixture of tri-n-butyl phosphate (TBP) and i-butyldodecylsulfoxide (BDSO) in toluene was investigated. The effects of the concentrations of extractant, nitric acid, sodium nitrate and sodium oxalate on the distribution ratios of uranium(VI) have been studied. The values of enthalpy change for the extraction reactions with BDSO, TBP and a mixture of TBP and BDSO in toluene were -23.2±0.8 kJ/mol, -29.2±1.4 kJ/mol and -30.6±0.6 kJ/mol, respectively. It has been found that the maximum synergistic extraction effect occurs when the molar ratio of TBP to BDSO is close to 1. The composition of the complex of the synergistic extraction is UO₂(NO₃)₂ ^. BDSO ^. TBP.     

Optimization of the extraction of iron(II) from water into cyclohexane with hexafluoroacetylacetone and tri-n-butyl phosphate

The extraction of iron(II) from water into cyclohexane with hexafluoroacetylacetone (HHFA) and tri-n-butyl phosphate (TBP) was optimized by using a simplex algorithm; pH, [HHFA], [TBP], and mixing time were varied. A central composite design was employed to examine in detail the region of the apparent optimum. Regression analysis of the central composite data demonstrated that in the region of the optimum, the response was essentially unaffected by small variations in the levels of the factors investigated.     

Solid-phase extraction of iron(III) with an ion-imprinted functionalized silica gel sorbent prepared by a surface imprinting technique

A new Fe(III)-imprinted amino-functionalized silica gel sorbent was prepared by a surface imprinting technique for selective solid-phase extraction (SPE) of Fe(III) prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Compared with non-imprinted polymer particles, the ion-imprinted polymers (IIPs) had higher selectivity and adsorption capacity for Fe(III). The maximum static adsorption capacity of the ion-imprinted and non-imprinted sorbent for Fe(III) was 25.21 and 5.10 mg g⁻¹, respectively. The largest selectivity coefficient of the Fe(III)-imprinted sorbent for Fe(III) in the presence of Cr(III) was over 450. The relatively selective factor (α_r) values of Fe(III)/Cr(III) were 49.9 and 42.4, which were greater than 1. The distribution ratio (D) values of Fe(III)-imprinted polymers for Fe(III) were greatly larger than that for Cr(III). The detection limit (3σ) was 0.34 μg L⁻¹. The relative standard deviation of the method was 1.50% for eight replicate determinations. The method was validated by analyzing two certified reference materials (GBW 08301 and GBW 08303), the results obtained is in good agreement with standard values. The developed method was also successfully applied to the determination of trace iron in plants and water samples with satisfactory results.     

Sorption of iron(III) in ionic and colloidal states on iron(III) oxide deposited on a silica gel sufrace

The sorption of iron(III) in ionic and colloidal states on iron(III) oxide deposited on a silica gel surface has been studied as a function of pH of aqueous solution by batch equilibrations. The behaviour of Fe³⁺ and colloidal Fe(III) on the sorbent column has also been investigated. Conditions for sorption of iron from aqueous solutions are given. The colloidal iron(III) can be quantitatively separated from Fe³⁺ on the sorbent column under given experimental conditions.     

Reversed phase extraction chromatography of chromium with tributylphosphate on silica gel

Summary A silica-gel column impregnated with TBP will extract various metal ions from hydrochloric acid media of various concentrations. Chromium(VI) is readily separated in this way from many other metal ions by use of selective extraction and elution. Chromium(VI) is easily separable from chromium(III). Chromium(VI) is separable from binary mixtures with alkali and alkaline earths, scandium, yttrium, cerium, zirconium, thorium, vanadium, manganese, iron, cobalt, nickel, copper, zinc, aluminium, gallium, indium, germanium, tin, lead, antimony, bismuth and tellurium by selective sorption, and from multicomponent mixtures [e. g. with copper or cobalt, vanadium and thorium; titanium, vanadium(V) and uranium(VI); iron(III) and molybdenum(VI)] by selective sorption and elution. The method is applicable to analysis of alloys.

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Extraktionschromatographische Trennung von Chrom mit Tributylphosphat auf Silicagel

Zusammenfassung Mit einer Silicagel-Säule, die mit Tributylphosphat imprägniert wurde, lassen sich verschiedene Metallionen aus salzsaurem Medium verschiedener Konzentration extrahieren. Chrom(VI) ist auf diese Art gut von vielen anderen Metallionen durch selektive Extraktion und Elution zu trennen. Es ist auch von Chrom(III) leicht trennbar. Ebenso kann man Chrom(VI) aus binären Gemischen mit Alkalien, alkalischen Erden, Scandium, Yttrium, Cer, Zirkon, Thorium, Vanadin, Mangan, Eisen, Kobalt, Nickel, Kupfer, Zink, Aluminium, Gallium, Indium, Germanium, Zinn, Blei, Antimon, Wismut und Tellur durch selektive Sorption trennen. Aus Mehrfachgemischen, z. B. mit Kupfer oder Kobalt, Vanadin und Thorium; Titan, Vanadin(V) und Uran(VI); Eisen(III) und Molybdän(VI) ist es ebenfalls durch selektive Sorption und Elution trennbar. Das Verfahren eignet sich für die Analyse von Legierungen.

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Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.     

Highly selective determination of rhodium(III) using silica gel surface-imprinted solid-phase extraction

A novel Rh(III)-imprinted amino-functionalised silica gel sorbent was prepared by a surface imprinting technique for preconcentration and separation of Rh(III) prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Compared with the traditional solid sorbents and non-imprinted polymer particles, the ion-imprinted polymers (IIPs) had higher adsorption capacity and selectivity for Rh(III). The maximum static adsorption capacity of the imprinted and non-imprinted sorbent for Rh(III) was 29.86?mg?g^?1 and 11.23?mg?g^?1, respectively. The imprinted Rh(III) was removed with 2?mL of 3% thiourea?+?2?mol?L^?1 HCl. The obtained imprinted particles exhibited excellent selectivity and rapid kinetics process for Rh(III). The relatively selective factor (α_r) values of Rh(III)/Ru(III), Rh(III)/Au(III), Rh(III)/Pt(IV), Rh(III)/Ir(IV), Rh(III)/Pd(II) were 26.7, 39.0 29.2, 28.1, 43.7, respectively, which were greater than 1. The detection limit (3σ) of the method was 0.26?µg?L^?1. The relative standard deviation of the method was 1.79% for eight replicate determination of 10?µg of Rh³⁺ in 200?mL water sample. The method was validated by analysing standard reference material (GBW 07293), the results obtained is in good agreement with standard values. The developed method was also successfully applied to the determination of trace rhodium(III) in geological samples with satisfactory results.     

Selective extraction of cerium(IV) on tri-n-butyl phosphate and thenoyltrifluoroacetone loaded polyurethane foam

A method for the selective extraction of cerium (IV) on tri-n-butyl phosphate and thenoyltrifluoroacetone loaded foams is described. Parameters affecting the extraction of the metal ion, such as pH, reagent concentration and equilibration time have been investigated. Effects of ten diverse cations have also been studied. The method can be applied to preconcentrate and determine cerium in glasses.This work was performed at the University of Veszprém, Department of Radiochemistry, by A.R. acting as guest research fellow.     

Reversed-phase liquid chromatography of the twenty-two tetrachlorodibenzo-p-dioxin isomers on pyrenylethyl- and octadecylsilylated silica gel columns

To purify the tetrachlorobenzo-p-dioxins synthesized for chemical and biological reference standards, reversed-phase liquid chromatography on pyrenylethyl- and octadecylsilylated stationary phase (PYE and C18) columns was employed with 100% methanol. The pyrenylethyl phase satisfactorily separated isomers resulting from mixtures of reaction products which had not been adequately separated with conventional C18 or silica gel. The use of a single chromatographic mode, liquid chromatography, and a single mobile phase with columns of distinctly different properties, C18 and PYE, separates 20 of the 22 isomers from each other and from the 1246/1249 pair. (The observed properties of the two columns afford insight into steric and polarizability differences among isomers.)     

Sorption of iron(II) and ruthenium(III)-triazine complexes on silica gel and its analytical applicability

2,4,6-Tri(2′-pyridyl)-s-triazine (TPTZ) complexes with iron(II) and ruthenium(III) were prepared. Their sorption and desorption features on silica gel have been investigated. Both complexes were strongly adsorbed. This has been utilized for separating and preconcentrating iron(II) and ruthenium(III) using TPTZ-impregnated silica gel. The chromatographic behavior of TPTZ on silica gel column was examined and found to be effective modifier for silica gel surface. The sorption capacity of silica gel for those metal-triazine complexes has been determined under static conditions and was found to be 5.28 × 10^–3 mM (Fe(TPTZ)₂²⁺) and 2.9 × 10^–3 mM (Ru(TPTZ)₂³⁺). Saturated methanolic solutions of KI or 25% NaClO₄ solutions desorbed both complexes quantitatively from the silica gel surface.     

Study on the synergic extraction of uranium(VI) with petroleum sulfoxides (PSO) and tri-n-butyl phosphate (TBP) mixture

The synergic extraction of uranium(VI) from nitric acid solution with petroleum sulfoxides (PSO) and tri-n-butyl phosphate (TBP) mixture has been studied. It has been found that maximum synergic extraction effect occurs if the molar ratio of PSO to TBP is two to three. The composition of the complex of synergic extraction is UO₂(NO₃)₂·TBP·PSO. The formation constant of the complex isK _PT=8.19. The effect of extractant concentration, nitric acid concentration, salting-out agent concentration and temperature on the extraction equilibrium of uranium(VI) was also studied.     

Quantitative extraction of chromium as blue perchromic acid with tri-n-butyl phosphate

Summary Chromium is readily and quantitatively extracted as blue perchromic acid by tri-n-butyl phosphate (25% solution in benzene). The colour remains stable for long periods. The chromium can be estimated either by back extraction into aqueous phase followed by volumetric determination or by direct measurement of intensity of the blue colour in organic phase. The method is free from interference by several elements.

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Zusammenfassung Chrom kann mit einer 25%igen Lösung von Tri-n-butylphosphat in Benzol quantitativ als blaue Perchromsäure extrahiert werden. Die Farbe bleibt lange Zeit beständig. Die Bestimmung des Chroms kann entweder volumetrisch nach Rückextraktion in wäßriger Phase oder durch direkte Messung der Farbintensität in der organischen Phase erfolgen. Mehrere Elemente, die auf ihren störenden Einfluß untersucht wurden, behindern die Bestimmung nicht.

     

Selective solid phase extraction and preconcentration of iron(III) based on silica gel-chemically immobilized purpurogallin

The immobilization of purpurogallin on the surface of amino group containing silica gel phase for the formation of a newly synthesized silica gel-bound purpurogallin (SGBP) is described. The surface modification was studied and evaluated by determination of the surface coverage value by both the elemental analysis and metal probe testing method, which was found to be 0.485 and 0.460 mmol g⁻¹, respectively. The metal sorption properties of SGBP were examined by a series of di- and tri-valent metal ions. The metal capacity values (mmol g⁻¹) for this series of metal ions were also determined under different buffer solutions (pH 1.0–6.0) as well as shaking times by the batch equilibrium technique. The results of this study confirmed the strong affinity and selectivity as well as the fast equilibration and interaction processes of SGBP and Fe(III) compared to the other tested metal ions. The reduction–oxidation process of iron(II)/iron(III) by SGBP was also studied and the results indicated only 2.1% reduction of iron(III) into iron(II). The selectivity incorporated into silica gel phase via the immobilization of purpurogallin was intensively studied for a several binary mixtures containing iron(III)—another interfering metal ion. The determined percentage extraction values of iron(III) from these mixtures were found to be in the range of 94–100%. The potential applications of SGBP as a selective solid extractor for iron(III) from natural tap water samples and real matrices were also studied and the results revealed good percentage extraction values of iron(III) (93.5−94.9±4.6−5.3%) of the spiked iron(III) in the acidified tap water samples as well as a high preconcentration factor of 500 was also established when SGBP was used as a selective solid phase extractor and preconcentration of iron(III) from acidified soft drink samples with percentage recovery values of (98.0−97.4±4.7−5.3%) of the spiked iron(III).     

Quantitative photoacoustic spectrometry : Determination of copper(II) and iron(III) complexed on modified silica gel samples

Calibration curves for copper(II) and iron(III) complexed with N-2-aminoethyl-3-aminoprophyltrimethoxysilane (AEAPS) immobilized on silica gel were prepared separately by photoacoustic spectroscopy (p.a.s.) based on a response function that combines the amplitude and phase values. The concentration of copper and iron in two-component samples are determined by obtaining the response at 600 and 400 nm, respectively, and referring to the calibration graphs. The relative errors in the concentrations determined by p.a.s. compared to atomic absorption spectrometry for copper range from ?9.3 to 3.2%, while for iron the range is ?52.7 to 4.5%. The large error for iron was due to its low concentration and absorptivity. With suitable chromophores and matrix, the response function extends the linear range of the calibration graph and can be used for nondestructive determination of two components.     

Liquid-liquid extraction of arsenic(III) with diluted tributyl phosphate

A 40% tributyl phosphate solution in xylene was used for the quantitative extraction of arsenic(III) from 4M hydrochloric acid/2M lithium chloride. It was stripped from the organic phase with water and determined volumetrically with potassium bromate. The period of equilibration was 3 min. Arsenic was extracted in presence of copper, cobalt, nickel, tin, bismuth, iron, cadmium and other elements which are usually associated with it in sulphide minerals and alloys.     

Thermodynamic study of extraction of cerium(III) and yttrium(III) with tributyl phosphate

To increase the efficiency of hydrometallurgical processing of lean rare-earth raw material, the effect of salt anion and metal cation on the characteristics of Ce(III) and Y(III) recovery from dilute aqueous solutions with tri-n-butyl phosphate was studied on the basis of the thermodynamic theory of extraction.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 9, 2004, pp. 1430–1434.Original Russian Text Copyright © 2004 by Chirkst, Litvinova, Chistyakov, Ionova.