Papers by Keyword: Zinc(II)

Abstract: The processes of Zn²⁺ and Pb²⁺ extraction by bulk liquid membranes containing di (2-ethylhexyl) phosphoric acid and tri-n-octylamine during galvanostatic electrodialysis accompanied by electrodeposition of the metals were studied. The effects of the current density as well as of composition of the liquid membranes and aqueous solutions on the rate of zinc (II) and lead (II) transport were determined. It was demonstrated that a practically complete removal of zinc (II) and more than 90 % extraction of lead (II) from the feed solutions containing 0.01 M ZnSO₄ or 0.01 M Pb (NO₃)₂ was achieved during 1.0 − 5.0 h of electrodialysis. A possibility of effective transfer of zinc (II) into dilute solutions of sulphuric, hydrochloric, perchloric and acetic acids was shown. Adherent zinc and lead coatings with a fine-grained structure have been deposited on the platinum cathode. More than 75% of zinc (II) and about 60% of lead (II) was deposited from solutions of sulfuric acid and perchloric acid, respectively.

Abstract: The paper presents a novel method for the separation/enrichment of trace Zn²⁺ using NH₄SCN –dodecyl dimethyl benzyl ammonium bromide (DDBAB)-water system.The effects of different parameters on the enrichment yield of Zn²⁺ have been investigated. The possible enrichment mechanism of Zn²⁺ was discussed.The results show that under the optimum conditions, Zn (SCN)₄^2- produced by Zn²⁺ and SCN^- reacts with DDBAB cation (DDBAB ⁺) to form the water-insoluble ternary association complex of [Zn (SCN)₄](DDBAB)₂, so Zn²⁺ was enriched quantitatively.While Al³⁺,Mn²⁺,Ni²⁺ and Pb²⁺ could not be enriched. Thereby, the quantitative separation of Zn²⁺ from the above metal ions could be achieved.A new method for the separation/enrichment of trace zinc was established. The proposed method has been successfully applied to the separation/enrichment of trace Zn²⁺ in the samles of synthetic water, and the enrichment yield is 96.4%-99.5%.

Abstract: A hetrobimentallic complex of Zn[Bi(edta)]₂•8H₂O was synthesized under hydrothermal condition and characterized by means of X-ray single crystal diffraction, element analysis, FT-IR spectra and thermal analysis. The complex is monoclinic, space group C2/c with a =2.3532(8) nm, b=0.8675(3) nm, c=1.6116(6) nm, β=98.114(6) °, V=3.2569(19) nm3, Z=4，Dc= 2.455 g•cm^－3，μ= 11.615mm－1. Bridging edta4－ anions between Bi(III) atoms result into infinite 1D zigzag chain. [Bi(edta)]－anions and [Zn(H₂O)₆]²⁺ cations are bonded through hydrogen bonds to form network structure. The thermal decomposition of the complex proceeds dehydration, pyrolysis of ligand, and decomposition of salt, and the final residue is inorganic oxide. The thermodynamic parameters ( ΔH、ΔG and ΔS) and kinetic parameters (activation energy Ea and the pre-exponential factor A) for the pyrolysis of ligand have been calculated.

Abstract: The synthesis of a new triazene reagent 1-(4-antipyrine)-3-(sulfanilic acid)-triazene (ASTA) and is proposed as a new sensitive reagent for the extractive spectrophotometric determination of Zinc(II) was established. The results showed that in the presence of micromulsion Tween-80, ASTA could reacted with Zn ( Ⅱ) to form a red stable complex of which the molar ratio of reagent︰metal was 2︰1 in Na2B4O7-NaOH medium. The maximum absorption peak of the complex was located at 520 nm with the apparent molar absorption of 1.7×105 L•mol-1•cm-1. Beers law was obeyed in the range of 0.3～5.0 μg/10 mL for Zn (Ⅱ) and the detection limit was 0.11 mg/L. Many ions did not interfere the colour reaction system due to the existence of ammonia. This method was applied to determination of Zn (Ⅱ) in water samples, and the results were in accordance with those obtained by AAS method. Recovery was in the range of 96.5～101.5 % and the RSD(n=6) was not more than 1.4%.

Abstract: A new chelating resin, pyrocatechol violet (PV) immobilised on Amberlite XAD-4 polymeric matrix, was prepared. The resulting chelating resin has been characterised by elemental analysis, infrared (IR) spectra and textural analysis (BET). The resin was used for the preconcentration of Zn (II) prior to its determination by flame atomic absorption spectrometry (AAS). The optimization of experimental conditions during the quantitative extraction of Zn (II) by the resin phase was performed using factorial design including pH, amount of resin, and contact time. The phase exchange kinetic studies performed of Zn (II) revealed that equal 40 min was sufficient for reaching equilibrium metal ion sorption. Sorption is quantitative in the pH range of 5 – 5.5 (recovery 98 – 99%).