Consecutive sorption of molybdenum(VI) and chromium(VI) from a single sample onto fiber materials filled with an anion exchanger and their solid-phase determination with phenylfluorone and diphenylcarbazide

We have considered the possibility of the sorption-spectrometric determination of molybdenum(VI) with phenylfluorone and chromium(VI) with diphenylcarbazide from a single sample by consecutive sorption from different media onto fiber materials filled with an AV-17 anion exchanger. The dependences of analytical signals of molybdenum and chromium on the sorption conditions (pH of the initial solution, NaCl concentration, sizes of the support disc, agitation time) have been studied in the batch mode. The conditions of analytical signal registration have been determined and the analytical ranges have been established (0.01–0.06 μg/mL for Cr and 0.02–0.2 μg/mL for Mo). It has been demonstrated that molybdenum and chromium can be determined at their ratios from 1: 1 to 5: 1 from a single sample after chromium sorption from 0.1 M HCl and molybdenum sorption at pH 4 by diffuse-reflection spectroscopy or visual test. The selectivity of molybdenum and chromium determination in the presence of interfering ions has been studied.     

A test method for determining palladium in chloride solutions on the solid phase of a fibrous anion exchanger

The sorption of palladium(II) from chloride solutions on polyacrylonitrile fiber filled with the AV-17 anion exchanger (PANF-AV-17) and its subsequent determination with p-nitrosodiethylaniline on the solid phase were studied. The results of determining palladium with this reagent on the solid phase of polyacrylonitrile fiber filled with the KU-2 cation exchanger and the AV-17 anion exchanger were compared. A test method was developed for determining palladium on the PANF-AV-17 solid phase. Sorption was performed in the batch mode; the analytical signal was estimated by measuring the diffuse reflection coefficient or visually using a color scale. The detection limit was 0.005 µg/mL; the range of the calibration scale was 0–0.2 µg/mL at the volume of the test solution 10–20 mL. The accuracy of the procedure was verified by the added-found method in the analysis of tap water and a standard reference sample of natural sodium chloride water. The relative standard deviation was no more than 25%; the time of the analysis of 5 or 6 samples was 25–30 min.Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 1, 2005, pp. 85–90.Original Russian Text Copyright © 2005 by Dedkova, Shvoeva, Savvin.     

Determination of vanadium(V) and chromium(VI) in a single sample on a fibrous ion exchanger disk

The determination of vanadium(V) and chromium(VI) in a single sample on a support disk was studied. Polyacrylonitrile fiber filled with an AV-17 anion exchanger was used as a solid phase. After adsorption, the elements were successively detected in the solid phase by color complexation reactions of vanadium with 8-hydroxyquinoline-5-sulfonic acid and chromium with 1.5-diphenylcarbazide. A procedure was developed for the adsorption-spectroscopic determination of 0.04–0.4 μg/mL vanadium(V) and 0.01–0.05 μm/mL chromium(VI) at V: Cr ratios of 1: 1 to 10: 1 in the dynamic mode. The limits of detections for vanadium and chromium were 0.04 and 0.005 μg/mL, respectively. It was shown that the background salt content of potable water had no appreciable effect; no preliminary sample preparation was required.     

Sorption-spectrometric determination of thorium(IV) and uranium(VI) with the reagent Arsenazo III on the solid phase of a fibrous material filled with a cation exchanger

The possibility of the use of organic reagents of the Arsenazo III group for the sorption-spectrometric determination of elements on fibrous cation-exchange materials was examined. The conditions of the sorption of Arsenazo III with the use of diphenylguanidinium chloride on the strongly acidic fibrous cation exchanger PANV-KU-2 were found. Procedures for the determination on the solid phase were developed for thorium in 7 M HNO₃ in the presence of 30-fold amounts of uranium with the detection limit of thorium of 0.005 μg/mL and for uranium in 0.05 M HCl in the presence of fivefold amounts of thorium with a detection limit of uranium of 0.05 μg/mL. The conditions were found for the selective preconcentration of thorium and uranium in the presence of each other, and a procedure was developed for their separate sorption-spectrometric determination.     

Adsorption-spectroscopic method for multielement analysis: Determination of Cr(VI), V(V), Ni(II), and Cu(II) from one sample using a two-layer adsorbent

The possibility of preconcentrating vanadium, chromium, copper, and nickel by the simultaneous adsorption in a flow-through mode on a two-layer adsorbent and the determination of metal ions by diffuse reflectance spectroscopy was studied. The adsorbent was made of a polyacrylonitrile fiber, one layer of which was filled with an AV-17 anion exchanger (PANV-AV-17), while another layer, with a KU-2 cation exchanger (PANV-KU-2). The procedure was based on the simultaneous preconcentration of vanadium and chromium on the first disk and nickel and copper on the second disk, by pumping the analyzed solution through both disks in a flow-through cell. Then, vanadium was determined on the disk of PANV-AV-17 with 8-hydroxyquinoline-5-sulfonic acid in 0.1 M HCl; next, chromium was determined with 1,5-diphenylcarbazide; the complex of vanadium was decomposed by 0.5 M H₂SO₄ and ascorbic acid. In the PANV-KU-2 disk, nickel was determined with dimethylglyoxime and then copper was analyzed with sodium diethyldithiocarbamate; the complex of nickel was decomposed with 1 M HCl. The selectivity factors were determined. A procedure was developed for the dynamic adsorption-spectroscopic determination of the following elements present simultaneously (μg/mL): V, 0.01–0.05; Cr, 0.002–0.015; Ni, 0.02–0.10; and Cu, 0.02–0.15. The results of analysis of model solutions are presented for different component ratios, RSD < 20%.     

Complex formation of thiocyanate ions with iron(III) on the solid phase of fibrous ion exchangers

Characteristics of complex formation of SCN^–-ions with iron(III) on fibrous materials filled with an AV-17 anion exchanger (PANV–AV-17) and a KU-2 cation exchanger (PANV–KU-2) are studied by diffuse reflection spectroscopy. Sorption conditions of thiocyanate ions on PANV–AV-17 in the dynamic mode and the influence of concentrations of Cl^–, SO ₄ ^2- and NO ₃ ^- on the sorption and analytical signals of thiocyanate complexes are studied. Sorption conditions of iron(III) on PANV–KU-2 and the conditions of formation of thiocyanate complexes are studied. Systems for the sorption–spectroscopic determination of 0.1–0.7 μg/mL of SCN^–-ions in aqueous solutions of pH 5 ± 1 on PANV–AV-17 and test-determination of 5–30 μg of SCN^–-ions on PANV–KU-2 are proposed.     

Sequential determination of nickel(II) and zirconium(IV) with dimethylglyoxime and arsenazo III after adsoprtion on one substrate disc

The possibility of the sequential determination of nickel with dimethylglyoxime and zirconium with arsenazo III from a single aliquot portion using polyacrylonitrile fiber as a solid phase impregnated with a KU-2 cation exchanger is studied. Conditions for the simultaneous adsorption of nickel and zirconium in the dynamic mode from 0.01 M HNO₃ are found as along with the ones for their sequential determination on one disc. The calibration functions are linear in the range 5–50 ng/mL, the detection limits for both elements are 2 ng/mL. In their simultaneous presence, the determination of nickel and zirconium is not affected by 10-fold weight amounts of Fe(III), Cu(II), Co(II), Al, Mn(II), Pb, Zn, Cd, Cr(VI), Mo(VI), and V(V). A method is proposed for determining nickel and zirconium from a single aliquot portion on a single substrate disc at their ratios from 1: 1 to a 5-fold excess of each element.     

Determination of Lead with 4-(2-Pyridylazo)resorcinol after the Sorption of Lead as its Thiosulfate Complex on a Fibrous Sorbent Filled with AV-17

The sorption of lead from a thiosulfate solution on a fibrous material filled with AV-17 (PANF-AV-17) was studied. Lead was determined by the color reaction with 4-(2-pyridylazo)resorcinol (PAR) on the solid phase by diffuse reflectance spectrometry. Optimal conditions were selected for lead sorption (pH 4.5 ± 0.5) and determination (pH 10); the selectivity of the determination was studied. A new system Pb–thiosulfate–(PANF-AV-17)–PAR was proposed for the determination of lead on the solid phase. A procedure was developed for the determination of lead in fresh water with the detection limit 0.01 mg/L and RSD < 25%.     

Sorption-spectrometric determination of lanthanum in the presence of uranium and thorium with the reagent Arsenazo M on the solid phase of fibrous filled sorbents

The possibility of the determination of La(III) in the presence of U(VI) and Th(IV), a solid phase with the reagent Arsenazo M, was examined. It was demonstrated that the determination of lanthanum with Arsenazo M in 0.05 M HCl in the presence of 3-, 2-, 1-, and 10-fold amounts of U(VI), Th(IV), Zr(IV), and Ti(IV) is possible after sorption on polyacrylonitrile fiber filled an ion exchanger with iminodiacetate groups (PANV-ANKB-50). For sorption under the optimum conditions at pH 5, the detection limit of lanthanum is 0.01 μg/mL. The method for the determination of lanthanum was verified by the added-found method in the analysis of tap water. To decrease the matrix effect, it is recommended to perform sorption in the analysis of water at pH 2.5. In this case, the detection limit of La(III) is 0.02 μg/mL, RSD < 20%. The time of the analysis of 5 or 6 samples is no longer than 20 min.     

Use of Two-Layer Supports for the Sorption–Spectrometric Determination of Chromium(VI), Copper(II), and Nickel(II) from a Single Sample in a Flow System

The determination of three elements from a single sample on a two-layer support in the flow mode was studied. One layer is a disk of a fiber material filled with the AV-17 anion exchanger, and the other is a disk of a material filled with the KU-2 cation exchanger. The method is based on the simultaneous preconcentration of elements by pumping a test sample through two disks in a flow cell, the separation of layers, and subsequent detection of chromium on the support filled with AV-17 using 1,5-diphenylcarbazide. The support filled with KU-2 is used for the sequential determination of nickel with dimethylglyoxime and copper with sodium diethyldithiocarbamate in 1 M HCl. The nickel dimethylglyoximate is decomposed under the action of 1 M HCl; its 10-fold amounts do not interfere with the determination of copper. This method provides the determination of chromium, copper, and nickel at a level below the maximum permissible concentration for potable water; at the ratio Cr : Ni : Cu = 1 : 10 : 20, RSD is lower than 10%. The time of the determination of the three elements from a single sample is 25–30 min.     

Sorption-spectroscopy and test determination of uranium(VI) and iron(III) from a single sample on the solid phase of fiber materials filled with an AB-17 ion exchanger

Diffuse reflectance spectroscopy has been used for the study of the sorption of malonate and glycolate complexes of uranium(VI) and iron(III), present simultaneously in solution, onto the solid phase of fiber materials filled with an AB-17 anion exchanger. In the form of malonate complexes uranium(VI) is determined in 0.5 M HCl on substrate discs with immobilized Arsenazo III, while iron(III) is determined on substrate discs with potassium thiocyanate in 0.5 M HCl. The dependence of the analytical signals on the concentrations of U(VI) and Fe(III) is linear in the ranges 0.02–0.16 μg/mL; the detection limit is 0.01 μg/mL. The possibility of analysis of U(VI) and Fe(III) mixtures in ratio from 1: 5 to 5: 1 in the presence of 2-fold concentrations of Zr(IV), Th(IV), and Ti(IV), 5-fold concentrations of Bi(III), 10-fold concentrations of Cu(II), 20-fold concentrations of La(III), 100-fold concentrations of Ni(II) and Zn(II), and 200-fold concentrations of Co(II) and Ca(II) has been demonstrated. Standard color scales in the concentration range from 0.02 to 0.2 μg/mL have been used for the visual determination of uranium(VI) and iron(III).     

Sorption-spectrophotometric determination of lanthanum,gadolinium, and ytterbium using chlorophosphonazo III on a PANF-Chel adsorbent

The possibilities of the sorption-spectroscopic determination of the sum of rare-earth elements have been studied on an example of La, Gd, and Yb as representatives of the light, middle, and heavy rare earth elements. The determination is carried out after the sorption from solutions with pH 3 onto the surface polyacrylonitrile fiber loaded with a Chel-100 ion exchanger followed by complexation with Chlorophosphonazo III. A dynamic version of the sorption-spectroscopic determination of the sum of La, Gd, and Yb has been developed for the concentration range 5–30 ng/mL with a detection limit of 3 ng/mL. The method was tested in the analysis of model solutions of CaCl₂, FeCl₃, and TiCl₄; RSD < 20%.     

Sorption-spectroscopy determination of zirconium on a PANV-KU-2 fibrous ion exchanger using Arsenazo III

The sorption and complexation of zirconium with Arsenazo III have been studied on a polyacry-lonitrile fibrous material filled with strongly acidic KU-2 cation exchanger in strongly acidic media. The optimal conditions have been chosen for the sorption-spectrophotometric and test determination of zirconium by diffuse reflection spectroscopy or visual testing. The limit of zirconium detection is 0.02 ??g/mL. The procedure was tested in the analysis of model solutions of ammonium molybdate and vanadate and copper chloride using the standard addition method.     

Color reactions of vanadium(V) with 8-hydroxyquinoline-5-sulfonic acid and ascorbic acid on PANV–AV-17 disks

The adsorption of vanadium(V) and 8-hydroxyquinoline-5-sulfonic acid (HQS) on polyacrylonitrile fiber disks filled with an AV-17 (PANV–AV-17) anion exchanger is studied by diffuse reflection spectroscopy. Vanadium(V) at pH 5?7 is adsorbed on PANV–AV-17; when a HQS solution is applied to the disk, a yellowish green complex compound formed, which changed color to almost black after the treatment of the disk with a HCl solution. The presence of sulfo groups in the HQS molecule ensures the preconcentration of the reagent on PANV–AV-17 disks with the registration of an analytical signal after the treatment of the disk with NaVO₃ and 0.1 M HCl solutions. A linear dependence of the analytical signal is observed in the HQS concentration range of 1?10 μg/mL. The presence of 20-fold amounts (by weight) of 8-hydroxyquinoline (HOQ) does not interfere with the determination. When ascorbic acid is applied to the disk with a vanadium(V)?HQS?HCl complex, the color changes from black to green. A test method for the determination of ascorbic acid is proposed. 8-Hydroxyquinoline can be determined by the intrinsic color of the adsorbate on PANV–KU-2 in the range of concentrations of HOQ solution in two drops 5?100 μg.     

Test Determination of Cu(II), Ni(II), and Cr(VI) in a Single Sample

It was shown that Cr(VI), Ni(II), and Cu(II) can be simultaneously adsorbed on a solid phase consisting of two filled fibrous disks and then determined visually using organic reagents. One sorbent disk, a fibrous material filled with an AB-17 anion exchanger, was used to determine chromium by its reaction with 1,5-diphenylcarbazide. Another disk filled with an KU-2 cation exchanger was used for the simultaneous sorption of copper and nickel followed by the consecutive determination of nickel with dimethylglyoxime and copper with sodium diethyldithiocarbamate. The conditions were optimized for the determination of nickel in the presence of copper and of copper in the presence of nickel after decomposing its dimethylglyoxime complex with 1 M HCl. The detection limits were 0.02, 0.1, and 0.05 mg/L for Cr, Ni, and Cu, respectively. The time of analysis was no longer that 20 min.     

Sorption preconcentration and separation of Palladium(II) and Platinum(IV) for visual test and densitometric determination

We have demonstrated the advantages of the dynamic preconcentration and separation of Pd(II) and Pt(IV) on paper carriers modified with 3-methyl-2,6-dimercapto-1,4-thiopyrone. The optimal conditions of the solid-phase reaction have been determined in Pd(II) sorption; after its separation Pt(IV), has been preconcentrated by sorption as its dimercaptides. Test scales have been produced for the visual determination of 0.5–40 μg Pd(II) and 1–195 μg Pt(IV) in 10- and 100 mL-samples, respectively. In addition, a procedure of their sorption-chromaticity densitometry determination from a single aliquot portion has been developed with detection limits of 5 and 1 ng/mL, respectively, and a procedure of Pd(II) determination using a test strip (c _min = 0.40 mg/L) has been proposed. The procedures have been applied to the determination of palladium and platinum in electrolytes, sludges, and alloys.     

Separation of Y from Sr by zirconium vanadate gel ion-exchanger sorbent: kinetics and thermodynamic study

A new zirconium vanadate (Zr–V) ion-exchanger was synthesized and characterized for fast and selective separation procedure of ⁹⁰Y from ⁸⁹Sr. The method was based on ⁹⁰Y(III) sorption from aqueous HCl solution containing ⁸⁹Sr(II) onto Zr–V gel exchanger. The kinetics of Y(III) sorption from HCl solution by Zr–V exchanger was subjected to Weber–Morris, Lagergren, Bhattacharya and Venkobachar, and Bt models. Initially, the uptake of Y(III) onto the exchanger was fast followed by kinetically first-order sorption with an overall rate constant, K _Lager = (3.55 ± 0.03) × 10^?4 min^?1. Film and intraparticle transport are the two steps that might influence Y(III) sorption. The negative values of ΔG of ⁹⁰Y retention dictate that, the process is a spontaneous. The negative values of ΔH and ΔS reflect the exothermic nature of ⁹⁰Y(IIsorption and the random uptake of ⁹⁰Y(III) onto Zr–V sorbent. Zr–V exchanger offers unique advantages of ⁹⁰Y(III) retention over conventional solid sorbents in rapid and effective separation of traces of ⁹⁰Y(III) from Sr. The exchanger was successfully packed in column for an effective separation of ⁹⁰Y.     

Separation of europium, cobalt and zinc on zirconium tungstate ion exchanger

Summary Amorphous zirconium tungstate inorganic ion-exchanger has been prepared under optimum conditions and characterized by IR, X-ray and thermal analysis. Surface area and capacity are determined. It has characteristic IR absorption peaks at 3242, 1628, 955, 868 and 432 cm^-1 and is thermally stable up to 450 °C. Its surface area was 16 m²/g with an exchange capacity of 0.541 meq/g. The sorption of radioactive europium from different media at ambient temperature by the zirconium tungstate (ZW) exchanger has been studied. The aim was to optimize the conditions for sorbing Eu from radioactive waste and cleaned the ZW from for recycling. The effect of contact time, metal concentration, pH and temperature has been measured. Percentual uptake of Eu(III) reaches 95% for HCl at pH 4 and increases with temperature indicating an endothermic sorption process. Uptake of Zn(II) and Co(II) on ZW from acetic acid was found to be 42% and 24% for cobalt and zinc, respectively. Desorption after saturation and the effect of other radioactive ions on the percentual uptake of Eu on ZW were investigated. A solution of 3M HCl releases 90%, 25% and 13% of the loaded Eu(III), Co(II) and Zn(II), respectively.     

Sorption and complexation of uranium(VI) and thorium(IV) with reagents Arsenazo III and Arsenazo M on fibrous filled sorbents

The possibility of the highly sensitive sorption-spectrometric determination of Th(IV) and U(VI) in the presence of each other on the solid phase of fibrous anion-exchange materials with Arsenazo M and Arsenazo III was examined. Polyacrylonitrile fiber filled with an exchanger AN-31, ANKB-50, or EDE-10p was used as the solid phase. It was demonstrated that the studied systems allow the selective determination of thorium in the presence of one-to twofold amounts of uranium. On PANV-EDE-10p with immobilized Arsenazo III, the detection limit of thorium in 2–10 M HCl is 0.002 μg/mL, and in 10 M HCl the presence of up to twofold amounts of uranium is permissible. A high sensitivity of the determination of uranium in 2–7 M HCl of 0.005 μg/mL, which has not been reported before, was attained. The time of the analysis of five or six samples is no longer than 20 min.     

ICP-OES determination of traces of Ru, Au, V and Ti preconcentrated and separated by a new poly(epoxy-melamine) chelating resin from solutions

A new poly(epoxy-melamine) chelating resin is synthesized from epoxy resin and used for the preconcentration and separation of traces of Ru(III), Au(III), V(V) and Ti(IV) ions from sample solutions. The ions analyzed can be quantitatively enriched by the resin at a flow-rate of 2 mL/min at pH 4, and quantitatively desorbed with 10 mL of 1 mol/L HCl + 0.2 g CS(NH₂)₂ at a flow-rate of 1 mL/min with recoveries of over 97%. The chelating resin can be reused 7 times without obvious loss of efficiency. Thousand-fold excesses of coexistent ions caused little interference during the enrichment and determination steps. The RSDs for the determination of 50 ng/mL Ru(III) and Au(III), 5.0 ng/mL V(V) and Ti(IV) were in the range of 1.5–4.5%. The recoveries of added standards in a real sample solution are between 96% and 100%, and the results for the ions analyzed in a nickel alloy sample are in good agreement with their reported values.