Chemical & Biological Dynamics

The explosion characteristics of chlorine dioxide gas have been studied for the first time in a cylindrical exploder with a shell capacity of 20l. The…

"The purpose of this paper is to present an overview of the properties, preparation methods, and applications of chlorine dioxide. In addition..." "Figure 3. Chlorine dioxide UV/vis spectrum"

The Atlas Accelerated UV testing devices focus on UV specific spectral ranges. They may be used in weathering tests that vary light/dark cycles, temperature, condensing humidity, water sprays, and irradiance control.

"maximum absorbance wavelengths for chlorine dioxide and hypochlorous acid were 360 nm and 292 nm"

(2021) "The disinfection of surfaces in medical facilities is an important element of infection control, including the control of viral infections such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). "

The emergence of severe acute respiratory disease (SARS-CoV-2) variants that cause coronavirus disease is of global concern. Severe acute respiratory disease variants of concern (VOC) exhibiting greater transmissibility, and potentially increased risk ...

We provide here a general view on the interactions of surfactants with viruses, with a particular emphasis on how such interactions can be controlled and employed for inhibiting the infectivity of enveloped viruses, including coronaviruses."

(2021) ****!!!!**** "Cleverin (Taiko Pharmaceutical Co. Ltd, Osaka, Japan) is a mixture of 500 ppm ClO2, 17,900 ppm sodium chlorite, 3300 ppm decaglycerol monolaurate, and 80 ppm silicone"

****!!!!*** "This narrative synthesis aimed to highlight the versatility and suitability of ClO2 in different settings (mostly for waters) and against different viral agents. It may be clear that ClO2 is not a therapeutic product. It cannot be used for healing human or animal tissues, with the exception of skin and mucosa antisepsis." "Bloodborne viruses (HIV-1, HCV, and HBV) may be completely eliminated from medical devices and human fluids after a treatment with 30 mg/L of ClO2 for 30 min."

(2021) {Note: More in-depth evaluation addressing cellular structure of specific areas of body contact, chemistry of surrounding body fluids, etc. would also need to be evaluated if in vitro exposures described herein were to be explored for use on or in areas of the body} "ClO2 is a small molecule with a molecular weight of 67.46, and it forms a stable radical.12 ClO2 is an oxidizer, which is reduced to chlorite ion (ClO2 -) by capturing an electron (ClO2 + e- → ClO2 -). The redox potential (Eº) is relatively high as 0.95 V, therefore does not harm the human microbiome."

"demonstration of the removal of uranium compounds from gaseous diffusion substrates." "...indicate that ClO2 will not exist in the presence of fluorinating agents..."

The sulfonamide antibiotic sulfamethoxazole (SMX) is a widely detected micropollutant in surface and groundwaters. Oxidative treatment with e.g. ozone or chlorine dioxide is regularly applied for disinfection purposes at the same time exhibiting a high potential for removal of micropollutants. Espec …

Xylanase pretreatment was used to improve the chlorine dioxide bleaching of bagasse pulp. The pulp was pretreated with xylanase, which was followed by a chlorine dioxide bleaching stage. The HexA content of the pulp and the AOX content of the bleaching effluent were measured using UV-Vis and GC-MS methods, respectively. The results showed that a good correlation occurred between HexA and kappa number. HexA content of the pulp decreased significantly after the xylanase pretreatment. The AOX content of the bleaching effluent decreased as HexA was removed from the pulp. It was found that AOX could be reduced by up to 29.8%, comparing XD0 with a D0 stage. Fourier transform infrared spectroscopy (FTIR) was employed to determine the breakage of chemical bonds in the pulp. It revealed that some lignin and hemicellulose were removed after xylanase treatment. The GC-MS results showed that some toxic chloride such as 2,4,6-trichlorophenol could be completely removed after xylanase pretreatment.

It is well known that pH is an important parameter for controlling the eucalyptus pulp bleaching...

Diclofenac (DCF), a synthetic non-steroidal anti-inflammatory drug, is one of the most frequently detected pharmaceuticals in the aquatic environment."

An investigation of the kinetics and mechanism for epoxidation of styrene and para-substituted styrenes by chlorite at 25 °C in the pH range of 5-6 is described. The proposed mechanism in water and water/acetonitrile includes seven oxidation states of chlorine (-I, 0, I, II, III, IV, and V) to accou …

Abstract A basic reaction scheme for the integral process of chlorine dioxide (OClO) photolysis at 366 nm in N2-saturated aqueous solution is proposed. The mechanism is supported by the initial quantum yield Φ°366 nm determined experimentally from OClO decay rates measured by electron spin resonance (ESR), chemical analysis of the stable products in solution and numerical simulation of the OClO profiles. In the concentration range 0.5 mM ≤ [OClO] ≤ 20 mM, Φ°366 nm = 0.52 with a 95% confidence interval of 0.50–0.55. Product concentrations determined after complete photobleaching were proportional to OClO initial concentration: [H+] = 0.856 [OClO]0; [HClO] = (0.141 ± 0.010) [OClO]0; [ Cl O 3 − ] = ( 0.551 ± 0.014 ) [OClO]0 and [Cl−] = (0.251 ± 0.015) [OClO]0. In the range of homogeneous light absorption, i.e. [OClO]0 ≤ 1.5 mM, OClO profiles and concentrations of the stable products in solution are well reproduced from numerical integration of the proposed mechanism. The reaction scheme requires the participation of dichlorine pentoxide (Cl2O5), which till now remains no isolated. However, reactions involving formation and hydrolysis of Cl2O5 are critical to reproduce the experimental profiles and explain the identity of the final products.

Insolation of carbon tetrachloride solutions of chlorine dioxide initiates a thermal decomposition, the magnitude of which may exceed that for the photoreaction with low light intensity. This thermal decomposition is inhibited by keeping the solutions at 3 °C. or by adding water.In contradiction to the findings of other investigators, it is found that chlorine and oxygen are not the only products of photodecomposition. As products of the photodecomposition of chlorine dioxide at the wave-lengths 3650 and 4360 Å, the oxides Cl2O, Cl2O6, and Cl2O7 as well as chlorine and oxygen appear. The quantum efficiency at λ 3650 Å is 2, and at 4360 Å, 1.In the unsensitized decomposition, concentration effects are observed which are greatly decreased when the solutions are stirred.In the bromine sensitized decomposition with 5460 Å, there is less chlorine monoxide but relatively as much Cl2O6 and Cl2O7 formed as in the unsensitized reaction.In the sensitized decomposition the quantum yield is independent of the concentration of chlorine dioxide, but depends on the light intensity."

(1932)

The actinic (i.e., photolysis) wavelength dependence of chlorine dioxide (OClO) photochemistry in solution is investigated. Femtosecond pump–probe studies performed with 355-nm photoexcitation are ...

"This time is significantly longer than the abstraction times observed for other systems demonstrating that Cl hydrogen abstraction from alcohols occurs in the presence of a significant energy barrier."

Photodissociation of ClO2 in aqueous solution at 400 nm results in the formation of ClO+O and Cl+O2. ClO and O geminately recombine to ClO2 in the electronic ground state (2B1), formed with an init...

"We have studied negative ion formation following low-energy electron impact (0-10 eV) to OClO including a time-of-flight analysis of the ions. The dominant feature is formation of a transient negative ion (OClO-*) by resonant electron capture in the vicinity of 0.7 eV which decomposes into Cl-, O-, ClO- and O2-. The total dissociative attachment (DA) cross section at the resonance maximum (0.7 eV) is near 10-15 cm2 with ClO-+O the dominant channel. Although the DA reaction O2+Cl- is exothermic by nearly 4 eV the Cl- ion appears with a mean kinetic energy of only 0.4±0.1 eV indicating effective vibrational excitation of neutral O2. Also observed at higher target gas pressures is the parent anion ClO2- which arises from an effective charge transfer process involving a metastable complex formed in the collision between the dominant DA product ClO- and the sample molecule OClO. "

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.