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Due to the wide applications of the Reactive Black B (RB−B) in textile industries, it is largely present within the aqueous environment which is a serious environmental threat. Previous studies were unsuccessful to completely remove the color of RB−B from the contaminated environment. In this work, the decolorization of aqueous solutions with RB−B was performed by Potassium bromate. It was found to be a promising oxidizing agent for chemical degradation of organic pollutant. The decolorization and degradation of Reactive Black B by potassium bromate in an aqueous acidic medium was carried out at 591 nm spectrophotometrically at laboratory scale. The reaction was studied under pseudo order conditions having concentration of BrO3− in excess than dye. Under constant conditions, the reaction was found to be first order with respect to both oxidant and reductant. The kinetic salt effect of added salt for the determination of reactive species in the rate‐determining step showed that the rate of reaction is directly related to the increasing concentration of salt, suggesting that two same charged species are involved in the rate‐determining step. Activation parameters were also calculated for the reaction. The highest decolorization percentage of RB−B (99 %) was obtained showing almost complete removal of color of dye from aqueous medium. The proposed degradation of RB−B with bromate was confirmed by qualitative and analytical tests (TDS, EC, UV‐Visible and FTIR spectroscopy). [ABSTRACT FROM AUTHOR]

Oxidation of the iodide ion is an important facet of the solar cells such as perovskite solar cells and dye‐sensitized solar cells. The rate of reaction undoubtedly depends upon several factors. Such parameters include reaction media, electrolyte, and the nature of solvents, and electrolyte. If these factors are optimized then the rate of the reaction can be controlled and could be used to get the maximum benefit out of it such as economically and industrially cost‐effective uses of the reaction and globally environmentally benign. We studied the kinetics of the oxidation of the iodide ion in the binary solvent system that consisted of 10% (v/v) tertiary butyl alcohol and water. The transition metal complex such as dicyanobis(phenanthroline)iron(III) oxidizes the iodide ion spontaneously without any external triggering with a fast rate at 293 ± 1 K. The reaction was probed under the pseudo–first‐order condition with an excess concentration of the iodide ion over dicyanobis(phenanthroline)iron(III) at 0.06 M ionic strength. The reaction was observed independent of the concentration of dicyanobis(phenanthroline)iron(III), that is, the zero order and third order with respect to the iodide ion in the selected solvent system. An overall third‐order was observed for the redox reaction. The value of the multiplication product of the molar absorptivity (ɛ), path length of the cuvette (b), and overall rate constant (k) was deduced to be 1.59 × 106 M−3 s−1. The observed zero‐order rate constant of the reaction was increased by the fractional (1.5) power of the concentration of protons in the excess concentration of acid 1 mM to 0.1 M. The multiplication product of ɛ⋅b to the fractional order rate constant (k′) was found 0.773 M−1.5 s−1 that confirms protonation of triiodide in acidic‐10% (v/v) tertiary butyl alcohol‐water. The effect of ionic strength showed a similar impact in different compositions of solvents such as 5, 10, and 20% (v/v) tertiary butyl alcohol‐water. The observed zero‐order rate constant was decreased upon increasing the ionic strength in each medium consisting of the binary solvent system. [ABSTRACT FROM AUTHOR]

The kinetics of the oxidation of tris (2,2'-bipyridine)iron(II) ([Fe(bipy)3]2+) by bromate ion (BrO3-) in aqueous medium have been investigated. The reaction was probed spectrophotometrically in the pH range 3.5-5.0, and from 0.01 to 0.1 mol/dm³ ionic strength. The kinetic runs were pursued to more than two half lives of the reaction. The pseudo first order rate constant was found independent of the concentration of tris (2, 2'-bipyridine) iron (II), and increases with increasing concentration of bromate ion in the reaction mixture. Protonation of BrO3- in the acidic medium yields monoprotonated (HbrO3) and diprotonated (H2BrO3+) species. The rising figure of the rate constant upon lowering the pH refers to the involvement of protonated species in the rate-determining step. A rise in the value of the rate constant with increasing ionic strength implies, however, the diprotonated species, H2BrO3+, as the reactive species among the two competing. Involvement of the other Br(V) species results in a complex reaction pathway, consequently. The rate law is suggested as follows: Rate = k1 [Fe ((2,2'-bipy)32+][HBrO 3] + k2 Kip [Fe ((2,2'-bipy )32+] [H 2BrO 33+]/ (1 + K ip [ H 2BrO 3+] [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the catalytic effect of Cu2+ ions and hydrogen ion concentration on the kinetics of [Fe (bipy)3]2+ oxidation in aqueous medium. It notes that the kinetics of iron (II) oxidation by iodine indicate that the redox reaction proceeds by analogous mechanism. The study reveals the stability of transition metal complexes in the 3.0-4.5 pH range for several days after its formation.

Dye-sensitized solar cells (DSSCs) are a technically and financially viable alternative to today's photovoltaic systems using p-n junctions. The two functions are isolated here, which are unlike traditional systems where the semiconductor is thought to perform both light absorption and charge carrier transport. This article discusses the potential use of dicyanobis(bipyridine)iron(III) to oxidize iodide as a sensitizer in DSSCs. However, it is critical to understand the kinetics of this essential process in order to understand the mechanism of electron transport. The oxidation of iodide by dicyanobis(bipyridine)iron(III) in three reaction media was studied: water, 10% v/v 1,4-dioxane-water, and 20% v/v 1,4-dioxane-water. The reaction was carried out in a regular laboratory setting, with no special sensitive conditions or the use of expensive materials, making it a cost-effective and practical method. Dicyanobis(bipyridine)iron(III) oxidized iodide in selected media at 0.06 M ionic strength and constant temperature. The reaction was subjected to a spectrophotometric analysis. The data were acquired by measuring the rise in visible absorbance as a function of time after the formation of dicyanobis(bipyridine)iron(II). The reaction proceeded with an overall fractional (0.5), first order, and third order in water, 10% media, and 20% media, respectively. The presence of dicyanobis(bipyridine)iron(III) in either of the reaction media had no effect on the rate. The effect of protons (H+) on the rate constant indicated resistance in water and catalysis in dioxane-water media containing 10–20% dioxane. When the ionic strength was raised, there was no change in the rate constant in water, but there was a deceleration in both binary solvent media. In an aqueous medium, the thermodynamic parameters of activation were computed as Ea 46.23 kJ mol−1, 24.62 M s−1, ΔH# 43.76 kJ mol−1, ΔS# −226.5 J mol−1 K−1, and ΔG# 111.26 kJ mol−1 (25 °C). By increasing the rate of the reaction to its maximum, this study discovered the binary solvent media with the highest catalytic efficiency, i.e., 20% v/v 1,4-dioxane-water, which may increase the efficiency of DSSCs without using any expensive material or unusual experimental conditions. [ABSTRACT FROM AUTHOR]

A new melilotic ester, meliloester [2-ethyl-hexyl-3-(2-hydroxyphenyl) propionate], was isolated from the whole plant of Melilotus alba. Its structure was elucidated on the basis of spectroscopic and mass spectrometric analyses, including EI-MS, HR-MS, and UV, IR, 1D and 2D-NMR spectroscopic studies.