Synthesis, structural characterization, DFT, kinetics and mechanism of oxidation of bromothymol blue: application to textile industrial wastewater treatment
Oxidation of bromothymol blue [BTB] by oxyanion potassium permanganate as a strong oxidizing agent in acid solutions using perchloric acid at a constant ionic strength has been obtained keto bromothymol blue [BTB] Keto and studied kinetically spectrophotometrically. Different characterization techni...
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Veröffentlicht in: | Chemical papers 2021-01, Vol.75 (1), p.297-309 |
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Sprache: | eng |
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Zusammenfassung: | Oxidation of bromothymol blue [BTB] by oxyanion potassium permanganate as a strong oxidizing agent in acid solutions using perchloric acid at a constant ionic strength has been obtained keto bromothymol blue [BTB]
Keto
and studied kinetically spectrophotometrically. Different characterization techniques for [BTB] and [BTB]
Keto
such as Fourier-transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–Vis), and optical properties have been used. The order about the permanganate ion is first, while a fractional first order was released as regards [H
+
] and [BTB] fractional first order. Dependence on the concentration of hydrogen ions in the concentrations indicates that the oxidation process is acid catalyzed. The absence of either transient Mn
III
and/or Mn
IV
as involving species in the oxidation process was verified by Mn
II
applied to the oxidation reaction. Formation of 1:1 intermediate complex formation kinetically was revealed during the rate-determination step. In the slowest step, two-electron transfer processes of the inner-sphere form have been proposed. A mechanism of the tentative reaction was proposed and explored concerning kinetic parameters. The density functional theory (
DFT
) by
DMol
3
and
CASTEP
was used for the optimization of dye [BTB] and [BTB]
Keto
as an isolated molecule. From the UV–Vis spectrum of [BTB] and [BTB]
Keto
, the
E
Direct
Opt
values are 2.849 eV and 2.35 eV using
Tauc`s
equation, respectively, related to direct transitions of electrons. Using
DMol
3
method with
DFT
simulation, the HOMO and LUMO values for [BTB] and [BTB]
Keto
as isolated molecule are 3.047 eV and 2.869 eV, respectively. The simulated FTIR, molecular electrostatic potential (MEP) and optical properties by
Gaussian software
and
CATSTEP
are in great agreement with the experimental study.
Graphic Abstract |
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ISSN: | 2585-7290 0366-6352 1336-9075 |
DOI: | 10.1007/s11696-020-01299-8 |