Mohamed A. Kabil

Sulfur Containing Reagent for Ion Flotation and Spectrophotometric Determination of Palladium(II)

Abstract The recovery of palladium(II) from acidic aqueous solutions and sea water using 4-phenylthiosemicarbazide (HPTS) and oleic acid surfactant (HOL) has been studied by ionic flotation. Hydrogen ion concentration, foreign ions, temperature and reagent concentrations have been investigated for attaining the maximum efficiency of palladium(II) flotation. HPTS is used to develop a rapid and sensitive method for the spectrophotometric microdetermination of Pd(II). Various analytical parameters have been evaluated. Beers law is obeyed over 2.0–14.5 ppm concentration range. The molar absorptivity of the formed 1:1 species is 0.49 x 104 L mol−1 cm−1 at 300 nm. The ligand protonation constant and the stability constants of its complexes with Pd(II) have been determined potentiometrically. The method is successfully applied to determine directly the added Pd(II) to sea water without flotation. Square-planar geometry was proposed for the isolated solid complex. Also, the flotation mechanism is suggested.

Simultaneous preconcentration flotation-separation and spectrophotometric determination of thorium, lanthanum and yttrium in some geological and enviromental samples

The extraction and preconcentration of a metal complex via surfactant-mediated phase separation was studied. A sensitive, selective and low-cost methodology for the determination of micro amounts of thorium, lanthanum and yttrium ions, using Eriochrome Cyanine R (ECR) with a flotation step prior to spectrophotometric determination was developed. The precipitate in the scum layer was quantitatively collected, stripped with 4 ml of 3% HCl and measured spectrophotometrically at 540 nm for Th(IV) and at 650 nm for both La(III) and Y(III). The stripping of Th(IV), La(III) and Y(III) from the scum layer was carried out in one step with different mineral acids. The stripping efficiency was found to be quantitative in the case of HCl. An excess amount of ECR was used to eliminate the interfering effects of various foreign species. The proposed procedure was applied to the determination of Th(IV), La(III) and Y(III) spiked in natural water samples and in some ore samples. Additionally, the mechanism of flotation of the metal chelate was proposed to be due to a physical interaction between the metal chelate and the oleic acid surfactant through the Van der Waals force.

Flame atomic absorption spectrometric investigation and determination of cobalt and copper using ethanolamine and triethanolamine as chemical modifiers

In the flame atomic absorption spectrometric investigation and determination of cobalt and copper, serious interfering effects were observed from borate and silicate on cobalt whereas borate, iron, indium and iridium interfered on copper. Enhancement, depression and absence of interferences were observed from a range of organic species on both cobalt and copper. All of these effects were attributed to chemical interferences as a result of their occurrence at different flame profiles to various extents. Ethanolamine (EA) and triethanolamine (TEA) were found to be effective chemical modifiers for complete elimination of the interferences encountered from the foreign species studied separately or in combination on cobalt and copper, respectively. The role of EA and TEA in eliminating the interfering effects originates from the solution for TEA whereas EA exerts its effect at the base of the burner where complexation with cobalt takes place by heating. In the reaction zone, an equilibrium for the decomposition of EA–Co or TEA–Cu species is established, yielding a consistent number of free cobalt and copper atoms. The excess amount of the modifier decomposes in the reaction zone, creating a reducing medium, which shifts the equilibrium in favour of analyte atomization. A procedure is proposed for the determination of cobalt or copper in some of their complexes.

USE OF ERIOCHROME CYANINE R FOR SEPARATION-FLOTATION AND MICRODETERMINATION OF HAFNIUM AND ZIRCONIUM IN REAL SAMPLES

Eriochrome cyanine R (ECR) is investigated as a collector for separation and flotation of hafnium from zirconium through the use of an oleic acid surfactant. Selective separation of Zr(IV) is achieved at pH 2 with maximum efficiency, whereas Hf(IV) is completely separated at pH 7.0–7.5. Excess ECR is used to avoid interferences from foreign ions without any effect on the separation efficiency. The procedure is successfully applied to the determination of Zr(IV) and Hf(IV) in real samples. A flotation mechanism is proposed.

Selective separation of Hg(II) from aqueous solutions by the precipitate flotation technique

SummaryThe flotation of Hg(II) ions as sulphide or iodide from aqueous solutions has been investigated, using oleic acid as surfactant. Selective separation from Cd ions has been achieved. There was no interference by Bi, Pb, Cu, Cd, Mn, Zn, Co or Ni.

Chemical modifiers for controlling interferences in the flame atomic absorption spectrometric determination of chromium(III) and chromium(VI) and their separation

The interfering effects of a range of organic and inorganic species on the atomic absorption signals of CrIII and CrVI were investigated. Such effects were eliminated by adding 20 mmol l–1 butylamine (BA) or N-cyanoacylacetaldehyde hydrazone (CyAH), as a chemical modifier, to both the sample and standard solutions. The role of BA was extended to separate CrIII from CrVI in admixture, with 100% recovery, using oleic acid as a surfactant at a pH of 5.5 ± 0.2. A mechanism for Cr atom population in the flame in the presence and absence of concomitants is suggested. Also, the role of BA or CyAH in eliminating interferences was investigated. The flotation mechanism is discussed. A simple, sensitive and rapid procedure for the separation and determination of CrIII from aqueous solutions was elaborated. The method was applied to the determination of CrIII in some complexes.

Triethanolamine as a releasing agent for controlling interferences in the atomic absorption spectrometric determination of gold and its use as a collector for the flotation of gold

The interfering effects of a range of organic and inorganic species on the atomic absorption signal of gold have been investigated. These interferences were completely eliminated by adding 6 mmol l–1 triethanolamine (TEA) to both the sample and standard solutions. The role of TEA was extended to the extraction of gold, with 100% recovery, from aqueous solutions, using oleic acid as a surfactant at a pH of 0.5–2.0. A mechanism for the effect of TEA in the flotation and in the atomic absorption investigation was suggested. A simple, sensitive and rapid procedure for flatation and the atomic absorption spectrometric determination of gold in synthetic mixtures and natural waters was elaborated.

Analytical Application of some Chemical Modifiers in Atomic Absorption Spectrometric Investigation and Determination of Mn(II) and Mn(VII)

Abstract The interfering effects of a range of cations, acids and organic compounds on the absorption signal of manganese(II) and manganese(VII) were studied in different media under diverse flame profile of different observation heights and fuel flow rates. The signal response of Mn(II) and Mn(VII) is slightly changed under different flame conditions, whereas it is markedly affected in the presence of concomitants. Several chemical modifiers were successfully applied for controlling such effects. Of these, boric acid, lanthanum chloride, strontium chloride, ammonium chloride and aluminium chloride were found to be effective as inorganic chemical modifiers in eliminating specific interferences on Mn(II) and Mn(VII) encountered from inorganic addenda. A combination of boric acid and strontium chloride, 500 ppm each, was able to overcome the potential effects of all inorganic interferences studied. Butylamine and piperidine were also used as excellent chemical modifiers organic reagents for controlling inor...

Micro-determination of gold using N-cyanoacylacetaldehyde hydrazone

A reliable and rapid procedure for the flotation and micro-determination of Au(III) using N-cyanoacylacetaldehyde hydrazone (CyAH) is proposed. CyAH forms a blue 1:1 complex (Kf=4.1×105 mol−1l−1) with Au(III) at pH 3–7. The maximum absorbance is obtained after 7 min; instantaneously by adding 3.3×10−3 mol/l H3PO4 or by heating to 55°C. Beers law is obeyed for 1–30 ppm of Au(III) with a molar absorptivity of 0.3×104 l mol−1 cm−1 at 550 nm.