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Kinetic study of atomization in atomic absorption analysis of solid samples using flame-furnace atomizer

100%
Lugovyy K., Buhay O., Alemasova A.
Open Chemistry
|
2010
|
vol. 8
|
issue 6
1244-1250
EN
Direct solid sampling analysis in atomic absorption spectrometry using flame-furnace atomizer allows to significantly decrease analysis duration, to avoid sample pollution and to exclude toxic reagents. The choice of chemical modifiers that decreases the detection limit and improves the repeatability of results is based on the mechanism of analyte-free atom formation. The kinetic approach developed here allows determination of pre-exponential factors k0 and apparent activation energies Ea of the atomization processes for Pb(II) and Cd(II) compounds and enables use of CaCO3 and KHF2 as effective chemical modifiers for soil samples. A fast and precise technique for lead and cadmium determination in soils using the proposed chemical modifiers was developed.
2
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An experimental and theoretical study of the polar [2+3] cycloaddition reactions between 1-chloro-1-nitroethene and (Z)-C-aryl-N-phenylnitrones

88%
Jasiński R., Mikulska M., Barański A.
Open Chemistry
|
2013
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vol. 11
|
issue 9
1471-1480
EN
Abstract Kinetic studies and B3LYP/6-31g(d) calculations indicate the polar nature of [2+3] cycloadditions between 1-chloro-1-nitroethene to (Z)-C-aryl-N-phenylnitrones. This is clearly confirmed by the activation parameters and the substituent and solvent effects. Graphical abstract [...]
3
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Removal of reactive dye brilliant red HE-3B from aqueous solutions by hydrolyzed polyacrylonitrile fibres: equilibrium and kinetics modelling

88%
Bilba D., Suteu D., Malutan T.
Open Chemistry
|
2008
|
vol. 6
|
issue 2
258-266
EN
A cheap and efficient fibrous hydrolyzed polyacrylonitrile (HPAN) sorbent was obtained by alkaline hydrolysis of Romanian polyacrylonitrile fibres. Scanning electronic microscopy and infrared spectroscopy were used to characterize the hydrolyzed product and to confirm its functionalization. The adsorptive potential of the proposed sorbent for reactive dye Brilliant Red HE-3B removal from aqueous solutions of pH=2 was examined by the batch technique as a function of dye concentration, temperature solution and contact time. The Freundlich, Langmuir and Dubinin-Radushkevich adsorption models were applied to describe equilibrium sorption data and to determine the corresponding isotherm constants. The thermodynamic parameters ΔG, ΔH and ΔS were also determined; the values obtained show that sorption of reactive dye on HPAN fibres is a spontaneous, endothermic and entropy-driven process. The kinetics of sorption of the reactive dye were analyzed using pseudo-first order and pseudo-second order kinetic models. The kinetic data fitted well to pseudo-second order kinetics, indicating the chemisorption of reactive dye onto the fibrous sorbent. The sorption mechanism of the dye onto hydrolyzed fibres was confirmed by FTIR spectroscopy. The dye-loaded HPAN sorbent can be regenerated by treatment with 0.1M NaOH and the regenerated sorbent may be reused in several adsorption-desorption cycles. The results of this study provided evidence that the HPAN fibres are effective for removing reactive dye Brilliant Red HE-3B from aqueous effluents. [...]
4
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Lead and cadmium atomic absorption determination in solid carbonized food samples using flame-furnace atomizer

88%
Lugovyy K., Buhay O., Alemasova A.
Open Chemistry
|
2014
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vol. 12
|
issue 3
386-390
EN
Direct atomic absorption solid sampling analysis using flame-furnace atomizer enables a significant decrease in the analysis duration, to avoid sample pollution and to exclude toxic reagents. The selection of the chemical modifiers decreasing the detection limit and improving the results repeatability is based on the analyte’s free atoms formation mechanism. The developed kinetic approach has allowed to determine pre-exponential factors k0 and apparent activation energies Ea of atomization processes for Pb(II) and Cd(II) compounds and to propose effective chemical modifiers sodium N,N-diethyldithiocarbamate and urea for food samples. The express and precision technique for lead and cadmium determination in food, using proposed chemical modifiers and carbonization techniques was developed.
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