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  • Author or Editor: M. Cheema x
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Abstract  

Neutron activation analysis has been used for the simultaneous determination of Cu, Mn, Zn and Na in plant materials. The heterocyclic dye PAN has been applied as a chelating agent to achieve the group chemical separation of Mn, Cu, Ni and Zn. Various factors which affect the formation and extraction of the PAN-metal chelates have been studied and optimized, using suitable aqueous solutions to selectively strip these elements from the organic phase. This procedure has been applied to the determination of these elements in ‘Bowen’s Kale’ and U.S. NBS Citrus-leaves and Tomatoleaves samples.

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Abstract  

The extraction of PAN chelates of the group IB, IIB and IIIA–VA elements from aqueous solutions of pH 1–10 into chloroform has been studied radiochemically. Re-extraction studies have been made to strip the metal ions from the organic phase into aqueous solutions of KCN, HClO4 and buffer solutions. The effects of certain masking agents on the extraction of these elements have also been studied. The extraction curves indicate the possibilities of devising group chemical separation procedures for use in activation analysis.

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Abstract  

A bis-2-(butoxyethyl ether) (DBC) solvent extraction method has been developed for the radiochemical separation of110mAg,210Pb,127Te and131I in varying concentrations of aqueous HNO3. Various factors were examined to determine the optimum conditions of extraction. The effect of various masking agents has been studied. The extraction of131I is enhanced to 99% at 2.4M HNO3 in the presence of KSCN.131I was stripped into aqueous sodium hydroxide from the oxygenated organic extractant. The method was then applied for the recovery of131I from neutron irradiated tellurium metal. The mechanism and reactivity of DBC with metal ions is described.

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Abstract  

Synergic extraction of hydrolyzable lanthanides Dy(III) and Sm(III) has been studied in the low pH range with 0.3M (HTTA-TBA) in chloroform from aqueous perchlorate media. The synergic coefficient was calculated at different pH's and was found maximum at pH 3 for both elements. The composition of the adduct was established as M(TTA)3.3TBA at pH 3. However, a mixture of the adduct of the type M(TTA)3.TBA was proposed at pH 5.9. The possible reaction mechanism at both pHs is discussed, the stability constant m,n formation constants Km,o and Km,n have been calculated.

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Abstract  

Extraction behaviour of the chelates of group VB–VIIB and VIII elements using 1-(2-pyridylazo)-2-naphthol (PAN) has been studied as a function of pH. Studies have been made to back-extract the metal ions from the organic phase into the aqueous solution containing the optimum concentration of KCN and HClO4 and buffers of appropriate pH. The masking agents such as citrate, cyanide, thiosulphate, fluoride and thiourea were used to achieve more specific separations. The studies indicate the potentiality of PAN as a useful solvent extracting reagent in devising group chemical separation procedures for activation analysis.

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Abstract  

A rapid procedure has been developed for the mutual separation of antimony and arsenic using tribenzylamine as the extracting agent. The extraction behaviours of Sb(III), Sb(V), As(III), As(V) and Au(III) have been studied as a function of the acidity of the aqueous phase. Various factors which affect the extraction of these complexes have been studied and optimized. The procedure was then applied to lead base alloy for the simultaneous determination of antimony, arsenic and copper. Chemical recoveries were quantitative and only about one hour is required for the chemical processing of duplicate samples.

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Abstract  

Synergic extraction of Eu(III) and Tb(III) with 2-thenoyltrifluoroacetone (HTTA) and tribenzylamine (TBA) as neutral donor ligand has been studied in chloroform from perchlorate media at lower pH range. The stoichiometric composition of the adduct was established as M(TTA)3 · 3TBA for both the elements, having a coordination number 9. The formation constants K3,0 and K3,3 and stability constant 3,3 of the organic phase reaction have been calculated. The effect of temperature on the extraction has also been studied. The adducts are stabilized by the large exothermic enthalpy change. The calculated thermodynamic functions such as H, S and G were used to elucidate the mechanism of synergism in which the coordination numbers of the lanthanide ions increased.

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Abstract  

Extraction of Hg(II), Se(IV), Mn(II) and Co(II) has been carried out with 1-phenyl-3-methyl-4-trifluoroacetyl-2-pyrazolin-5-one (HPMTFP) and triphenylphosphine oxide (TPPO) into chloroform from pH 1–10. Quantitative extraction of Hg(II), Mn(II) and Co(II) at pH 4 with equimolar 0.05M (PMTFP+TPPO) in chloroform was observed. Se(IV) remains unextracted at this pH range. The stoichiometric composition of the extracted complexes M(PMTFP)2·nH2O (M=Mn, Hg), M(PMTFP)2·2TPPO (M=Mn and Co) and Co(PMTFP)2·TPPO·H2O at less than 0.1M TPPO has been established. The formation constantsK m,0 andK m,n and stability constants m,n have been computed. The analytical method developed was applied to the IAEA standard reference material (SRM) potato fluor V-4 for the determination of these elements using NAA technique.

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Abstract  

Synergic extraction of Ni/II/ at pH 1 to 10 was studied using a mixture of 2-thenoyltrifluoroacetone /HTTA/ and tribenzylamine /TBA/ in chloroform. The synergist TBA enhances the extraction of Ni/II/ by an order of 5 from pH 3 to 5 having ionic strength 0.1M /H+, ClO 4 /. The synergic adduct was found to be Ni/TTA/2.2TBA. The equilibrium constants K2,0 and K2,2 and stability constant 2,2 have been ascertained radiometrically. The influence of various cations and anions on the extraction of Ni/II/ has been examined under optimal conditions. Back extraction of the adduct species in different acids of varying concentrations has been studied.

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Abstract  

Synergic solvent extraction of Pr(III), Ho(III) and Er(III) was carried out at pH3.5 with a mixture of 2-thenoyltrifluoroacetone (HTTA) and tribenzylamine (TBA) from perchlorate media, having ionic strength 0.1M(H+, ClO 4 ). The stoichiometmric composition of all three synergic adducts was established to be Pr(TTA)3·3TBA, Ho(TTA)3·3TBA and Er(TTA)3·3TBA. The formation constants KTTA and Ksyn and stability constant ±syn were also computed and found to be in the order ErHo>Pr. The effect of various anions on the extraction has also been studied.

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