Chemical & Biological Dynamics

The photochemical reaction dynamics of chlorine dioxide (OClO) are investigated using absorption and resonance Raman spectroscopy. The first Raman spectra of gaseous OClO obtained directly on resonance with the 2B1−2A2 electronic transition are reported. Significant scattering intensity is observed for all vibrational degrees of freedom (the symmetric stretch, bend, and asymmetric stretch), demonstrating that structural evolution occurs along all three normal coordinates following photoexcitation. The experimentally measured absorption and resonance Raman intensities are compared to the intensities predicted using both empirical and ab initio models for the optically active 2A2 surface. Comparison of the experimental and theoretical absorption spectra demonstrates that the frequencies and intensities of transitions involving the asymmetric stretch are well reproduced by the empirical model characterized by a double-minimum along the asymmetric stretch. However, the ab initio model is also found to reproduce a subset of the experimental intensities. In addition, the extremely large resonance Raman intensity of the asymmetric stretch overtone transition is predicted by both models. The results presented here taken in combination with the model for the 2A2 surface in condensed environments suggest that the phase-dependent photochemical reactivity of OClO is due to environment-dependent excited-state structural evolution along the asymmetric stretch coordinate.

"studies of the photolysis of OClO at 355 nm in water solution reveal a quantum yield of 0.1 +- 0.01 for Cl production."

The present study identified the active radical species in acidic sodium chlorite and investigated the feasibility of quantifying these species with the diethylphenylenediamine (DPD) method. Electron spin resonance (ESR) spectroscopy was used to identify the active species generated in solutions containing sodium chlorite (NaClO2). The ESR signal was directly observed in an acidified sodium chlorite (ASC) aqueous solution at room temperature. This ESR signal was very long-lived, indicating that the radical was thermodynamically stable. The ESR parameters of this signal did not coincide with previously reported values of the chlorine radical (Cl●) or chlorine dioxide radical (O = Cl●-O and O = Cl-O●). We refer to this signal as being from the chloroperoxyl radical (Cl-O-O●). Quantum chemical calculations revealed that the optimal structure of the chloroperoxyl radical is much more thermodynamically stable than that of the chlorine dioxide radical. The UV-visible spectrum of the chloroperoxyl radical showed maximum absorbance at 354 nm. This absorbance had a linear relationship with the chloroperoxyl radical ESR signal intensity. Quantifying the free chlorine concentration by the DPD method also revealed a linear relationship with the maximum absorbance at 354 nm, which in turn showed a linear relationship with the chloroperoxyl radical ESR signal intensity. These linear relationships suggest that the DPD method can quantify chloroperoxyl radicals, which this study considers to be the active species in ASC aqueous solution.

"Similarities in the photoreactivity of concentrated amorphous ice films containing OClO clusters and OClO adsorbed on ice suggest that OClO clusters may play a role in ice surface photochemistry."

"The intermediate is therefore identified as ClO and the new species as Cl_2O_3, chlorine sesquioxide, formed by reaction 5: ClO + ClO_2 → Cl_2O_3."

(2020). For chlorine dioxide (ClO2) at 60 ppm, the cell numbers were reduced by ∼5.45 log CFU cm−2. A combined treatment of 5 min of ultrasound plus 300 ppm NaOCl or 40 ppm ClO2, provided maximal efficacy,

"We observed Cl-, O-, O2-, and OCl- ions from the DEA measurements on OClO formed at various electron energies"

"The employed potential energy surface is the recently proposed single-sheeted double many-body expansion potential energy surface for the (2)A" ground-state of ClO2 based on multireference ab initio data."

"systems include the bimolecular reactions of ClO with HO, HO 2 , ClO, OClO, NO and NO 2 and some of their reverse processes"

The isomerization and decomposition of ClOO and OClO radicals and related Cl+O2 and O+ClO reactions have been investigated by ab initio molecular orbital and transition-state theory calculations. The species involved have been optimized at the PW91PW91/6-311+G(3df ) level and their energies refined by single-point calculations with the modified Gaussian-2 method. Predicted bond-dissociation energies of ClOO and OClO, D0(Cl–OO)=4.6 and D0(O–ClO)=58.5 kcal/mol, agree well with experimental values. Calculated rate constants for the Cl+O2→ClOO reaction in 160–1000 K at the high- and low-pressure limits can be expressed by k1∞=1.8±0.1×10−10 cm3 molecule−1 s−1 and k10(He)=1.66×10−19 T−5.34 exp(−675/T) and k10(O2)=1.26×10−16 T−6.22 exp(−943/T) cm6 molecule−2 s−1. For Ar and N2, theory underpredicts k10(M) below room temperature due to significant contributions from the “chaperon” mechanism involving Cl–M complexes. The corresponding rate constants for O+ClO→OClO are predicted to be: k2∞=4.33×10−11 T−0.03 exp(43/...

The mechanism for the reaction ClO+OClO has been investigated by ab initio molecular orbital and transition state theory calculations. Nine stable isomers of Cl2O3 (including optical isomers) are located at the B3LYP/6-311+G(3df ) level. The transition states between pairs of isomers are explored and the stability of the isomers and their dissociation mechanisms are discussed. The relative stability predicted by the modified Gaussian-2 (G2M) method at the G2M//B3LYP/6-311+G(3df ) level is ClOCl(O)O>ClOOOCl(C2)>ClOOOCl(Cs)>ClClO3(C3v)>cyc-ClOOCl(O)>ClOOClO. The formation of ClOCl(O)O is dominant at low temperatures, taking place barrierlessly with the second and third order rate constant, k1∞=3.0×10−10 cm3 molecule−1 s−1 and k10=1.1×10−17 T−5.5 exp(−398/T) cm6 molecule−2 s−1 in the temperature range of 200–400 K for N2 as the third-body. Over 500 K, formation of ClOO+ClO becomes dominant and ClOCl+1O2 is also competitive. Their overall rate constants can be given by kClOO=1.0×10−22 T2.8 exp(−78/T) and kClO...

"Chlorine and chlorine oxide radicals play an important role in the destruction of atmospheric ozone in thepolar stratosphere, through various photolytic or chemical processes.1–3 The self-reaction of ClO radicals can produce ClOO, OClO, Cl, O2, and Cl2, in addition to the recombination products including the three isomers of Cl2O2. The reaction has been investigated extensively experimentally and computationally. Although the ClOO radical is short-lived as a result of its low Cl-O2 bond energy of around 4.8 kcal/mol,5–7 it has been considered to be a temporary sink for the Cl atoms at low temperature in the stratosphere"

The calculation indicates that the dominant product for the title reaction is ClO + NO2 by the direct dissociation of the initial adduct, and the formation of the other products is much less likely since they are unfavorable kinetically."

****!!!!****!!!! (1993) "pure gaseous OclO is stable at room temperature in the absence of light for days and shows no tendency to dimerize, whereas ClOO rapidly decomposes to Cl and O2."

"design, develop and demonstrate a simple-to-operate and advanced, novel electrochemical ClO2 micro sensor (sensor cell with integrated potentiostatic control and signal-processing circuit) and demonstrate its successful operation with wireless data transmission. The proposed micro sensor will be rapid (less than 30 seconds for 90% of full response, T90), accurate, selective and capable of measuring 0 to 3000 ppm ClO2 in real-time with a detection limit of 2 ppb. " "configured for continuous unattended or handheld operation and it will be fully integrated with wireless data transmission and configured into a compact and lightweight monitor..." " ($100 to manufacture in quantities greater than 10,000 units"

"Bio-Cide International... developed 'stabilized chlorine dioxide'"... "thermostability, UV absorption spectrum, specificity of the paper chromatogram, microstructure and ionic chromatogram of this solution were studied, and contrasted with pure NaClO2 and ClO2. The results show that ClO2 in 'stabilized chlorine dioxide' solution exists in the form of chlorite ClO2-, carbonate exists in the form of bicarbonate... NCO3-, its pH being 8.5" "Conclusions stated above prove that in ‘‘stabilized chlorine dioxide’’ solution, ClO2 exists in the pattern of chlorite ClO 2-. So-called ‘‘stabilized chlorine dioxide’’ actually is the mixture of NaClO2 and NaHCO3."

{Lists maximum values for arsenic, and heavy metals; and pH value and density. Includes extensive list of various types of applications.}

"The precursor of chlorine dioxide (9) is activated with an acid-based product delivered into the DWLS, followed by a change of water pressure when animals are drinking water. So, the activation will occur just when it is needed: on-demand. This final product will help to control and manage biofilm formation. Removing biofilm and reducing biofilm formation helps to manage the negative impact on the taste and odor... Additionally, chlorine dioxide binds mineral elements, such as iron and manganese... These minerals have also been noted as fundamental precursors for bacteria growth"

"Novel pod for chlorine dioxide generation and delivery to control aerobic bacteria on the inner surface of floor drains"

"E. coli, Staphylococcus aureus, S. Enteritidis and C. jejuni."

"Sodium perborate has been used to increase the concentration of chlorine dioxide which can be placed in stable solution, the chlorine dioxide being bubbled into water containing sodium perborate. " "It has been discovered that the use of alkali metal (sodium) percarbonate instead of sodium perborate increases the amount of chlorine dioxide which can be held in stable solution as much as three hundred percent... In practice, about two parts by weight of percarbonate for each part of chlorine dioxide has been found to provide optimum stable C10 concentrations." "the same stable concentration of chlorine dioxide can be achieved at only a fraction (about 1%) of the cost using the relatively expensive percarbonate. " "invention also contemplates using the excess peroxide or active oxygen in the percarbonate by addition of sodium carbonate or bicarbonate to the percarbonate in sufiicient amount to utilize all the available active oxygen"

An antimicrobial preservative for use in an ophthalmic product that is well tolerated by the human eye, the preservative comprising 0.04% by weight of sodium chlorite, 0.02% by weight, 0.03% by weight, 0.04% by weight, or 0.05% by weight of hydrogen peroxide, and 0.2% by weight of boric acid, where the preservative does not generate chlorine dioxide, and where the preservative is at a pH of 7.4."

The efficacy of chlorine dioxide (ClO2) in detoxifying two potential bioterrorism agents, the trichothecene mycotoxins verrucarin A and roridin A, was evaluated...

****!!!!**** (2021) "Matching transformation system (MA-T) is an on-demand aqueous chlorine dioxide solution"