Organic chemistry
Shahryar Abbasi; Mahmoud Roushani; Hadi Noorizadeh
Abstract
In this work, we developed a method based on ultrasound-assisted emulsification microextraction (USAEME) for the determination of zinc and copper by flame atomic absorption spectrometry (FAAS). The method is based on the use of the organic solvent carbon tetrachloride (CCl4) as an extraction solvent. ...
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In this work, we developed a method based on ultrasound-assisted emulsification microextraction (USAEME) for the determination of zinc and copper by flame atomic absorption spectrometry (FAAS). The method is based on the use of the organic solvent carbon tetrachloride (CCl4) as an extraction solvent. In order to obtain a high enrichment factor, the effect of different parameters affecting the complex formation and extraction conditions (such as the type and volume of the extraction solvent, pH, the chelating agent amount, extraction time, extraction temperature and ionic strength) were tested. Under optimum conditions, the eight replicates mixture of the 100 ngmL-1 and 50 ngmL-1 for Zn(II) and Cu(II) ions, gave a mean absorbance of 0.055 and 0.061, with a relative standard deviation (RSD) of ±%3.2 and 2.9, respectively. The equations for the lines were A = 0.4921C + 0.0027 (R = 0.9998) and A = 1.0701C + 0.0032 (R = 0.9997), respectively. The limit of detection for Zn (II) and Cu(II) ions were 1.06 and 1.4 ngL−1, respectively. The calibration graph was linear in the range of 3.0–2000.0 ngmL−1 and 2.0-850.0 ngmL−1 for Zn and Cu respectively. In the proposed procedure, enhancement factors were 9.51 and 6.25 for Zn and Cu, respectively. This proposed method was successfully applied in the analysis of four real environmental water samples and good spiked recoveries over the range of 98.4–103.0% were obtained. This is a first research used USAEME for simultaneous determination Zn and Cu in water.
Physical chemistry
Mehdi Ghambarian; Zahra Azizi; Mohammad Ghashghaee
Volume 5, Issue 1, pp. 1-120, Serial No. 14 , January 2017, , Pages 28-34
Abstract
Density-functional-based and ab initio calculations were implemented at different computational levels to estimate the binding energy of Zn2+ ion adsorbed on the available sites of a silicate MEL-type adsorbent. B3LYP and MP2 were used in combination with the 6-31G*, 6-31+G*, LanL2DZ, 6-311+G*, and Def2-TZVP ...
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Density-functional-based and ab initio calculations were implemented at different computational levels to estimate the binding energy of Zn2+ ion adsorbed on the available sites of a silicate MEL-type adsorbent. B3LYP and MP2 were used in combination with the 6-31G*, 6-31+G*, LanL2DZ, 6-311+G*, and Def2-TZVP basis sets. The zinc cation was found to preferentially occupy the 6MR sites followed by the cage-like positions. Nevertheles, all of the available sites exhibited negative amounts for the Gibbs free energy and enthalpy of adsorption with the corresponding population-averaged values of –160.84 and –169.53 kcal/mol at the B3LYP/Def2-TZVP level. Overall, the B3LYP/LanL2DZ method illustrated the highest deviation from the others both in trends and absolute values of binding energy. While the absolute binding energy ranged from 131.23 to 230.79 kcal/mol over different sites, the population-averaged binding energies altered from 146.08 to 162.54 kcal/mol depending on the method employed.
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