Chemiluminescence Evidence Supporting the Selective Role of Ligands in the Permanganate Oxidation of Micropollutants

Abstract

The selective increase in the oxidation rate of certain organic compounds with permanganate in the presence of environmental "ligands" and reduced species has been ascribed to the different reactivity of the target compounds toward Mn(III), which bears striking similarities to recent independent investigations into the use of permanganate as a chemiluminescence reagent. In spite of the importance of Mn(III) in the light-producing pathway, the dependence of the oxidation mechanism for any given compound on this intermediate could not be determined solely through the emission intensity. However, target compounds susceptible to single-electron oxidation by Mn(III) (such as bisphenol A and triclosan) can be easily distinguished by the dramatic increase in chemiluminescence intensity when a permanganate reagent containing high, stable concentrations of Mn(III) is used. The differences are accentuated under the low pH conditions that favor the chemiluminescence emission due to the greater reactivity of Mn(III) and the greater influence of complexing agents. This study supports the previously postulated selective role of ligands and reducing agents in permanganate oxidations and demonstrates a new approach to explore the chemistry of environmental manganese redox processes.

Generation of Active Mn(III)aq by a Novel Heterogeneous Electro-permanganate Process with Manganese(II) as Promoter and Stabilizer

“…The results indicated that acidic condition was more conducive to DCF degradation in the E-PM-Mn 2+ process. This phenomenon could be attributed to the fact that Mn­(III) was in situ formed, and it was extremely reactive in acidic conditions for the rapid oxidation of DCF. , Moreover, the disproportionation of Mn­(III) increased with the pH under alkaline conditions, which resulted in the decrease of the DCF degradation ratio. In addition, to reduce the effects of pH changes during the reaction, batch tests were also conducted at pH 4 and 5 with buffer solution (10 mM acetic acid).…”

Fluorescence Optosensing of Triclosan by Upconversion Nanoparticles with Potassium Permanganate

“…The brown colloid Mn­(IV), which was formed as the intermediate when Mn­(VII) oxidizes TCS, can be observed by the naked eye. Although Mn­(VII) is generally converted to the Mn­(III) state when TCS is oxidized in the presence of a ligand, in the case of PBS, Mn­(IV) rather than Mn­(III) is formed. − Therefore, a certain amount of MnO 2 was formed and increased in the presence of TCS in the UCNPs@KMnO 4 solution. The UCL intensity of UCNPs was quenched by coating KMnO 4 because of the overlap between the absorption spectrum of KMnO 4 and emission spectrum of UCNPs.…”

“…In addition, Mn­(IV) can be aggregated by an oxidative process to form brown colloids. This is stabilized by preventing the disproportionate oxidation of KMnO 4 and the formation of intermediates is accelerated by the oxidation of TCS by Mn­(IV). − Furthermore, Mn­(VII) readily oxidizes TCS via several reactions including hydrogen abstraction, electron exchange, and direct oxygen transfer, thereby decreasing the adverse activity of TCS . Jiang’s group found that, during the Mn­(VII)/TCS reaction, the absorption band of inherent Mn­(VII) disappears from the range 490–590 nm .…”

The electronic structure of the aqueous permanganate ion: aqueous-phase energetics and molecular bonding studied using liquid jet photoelectron spectroscopy

“…1 Thus, MnO 4 À (aq.) is considered a versatile oxidizer suitable for green chemistry, 2 oxidation of micro-pollutants, 3 detection of organic compounds, 4 water disinfection, [5][6][7] and synthesis of energy materials. 8 This transition-metal complex has also been applied in energy conversion and storage systems, such as MnO 4 À (aq.)…”

“…However, specific sample temperatures (in the 280 AE 3 K range) were adopted in situations where PES peak spectral widths are compared or used to derive additional parameters. The pressures in the interaction chambers were maintained between 5  10 À4 and 1  10 À3 mbar using a combination of turbo molecular pumping (B2000 or B2700 L s À1 pumping speed for water vapour in the SOL 3 PES and EASI instruments, respectively) and two (SOL 3 PES) or three (EASI) liquid nitrogen-filled cold traps (B4.5  10 4 L s À1 pumping speed for water vapour per trap in both instruments). 43,45 The U49/2 PGM-1 beamline provided linearly, horizontallypolarized light and a focal spot size of approximately 100  80 mm 2 (horizontal  vertical).…”