Chemical & Biological Dynamics

"At a ClO2 dosage of 74 μM (5.0 mg L–1 as ClO2) and a UV fluence at 47.5 mJ cm–2, the UVA365/ClO2 AOP generated a spectrum of reactive species, including chlorine oxide radicals (ClO•), chlorine atoms (Cl•), hydroxyl radicals (HO•), and ozone at a concentration of ∼10–13, ∼10–15, ∼10–14, and ∼10–7 M, respectively. A kinetic model to simulate the reactive species generation in the UVA365/ClO2 AOP was established, validated against the experimental results, and used to predict the pseudo-first-order rate constants and relative contributions of different reactive species to the degradation of 19 micropollutants in the UVA365/ClO2 AOP. Compared to the well-documented UVC254/chlorine AOP, the UVA365/ClO2 AOP produced similar levels of reactive species at similar oxidant dosages but was much less pH-dependent and required much lower energy input, with much lower formation of chloro-organic byproducts and marginal formation of chlorite and chlorate.

Semantic Scholar extracted view of "The multiple roles of chlorite on the concentrations of radicals and ozone and formation of chlorate during UV photolysis of free chlorine." by J. Zhao et al.

"Among these oxidants, chlorine dioxide is the most likely to produce kinetics controlled by simple outer-sphere one-electron transfer, and this made it possible to describe the kinetics using a model based on Marcus theory.11 For that analysis, free energies of oxidation for phenols by chlorine dioxide were calculated using the E1/2 data from Suatoni et al., assuming—and then supporting—their claim that these E1/2's are the one-electron oxidation potentials for phenols."

****!!!!****!!!!**** " In practice, based on a 10% chlorine excess compared with the stoichiometry and a 95% efficiency, 1.41 g of pure sodium chlorite and 0.61 g of chlorine will be required to produce 1 g of CℓO2." "obtained by oxidizing a solution of sodium chlorite using chlorine or hydrochloric acid" "Sodium chlorite solutions can be prepared from sodium chlorite powder. Water that has first been softened will need to be used to prevent calcium carbonate from precipitating."

{CDG Environmental} Method for producing stable sodium chlorite by pelletization of granular sodium chlorite with metal salt or salts forming hydrates with water of hydration in the pellets being more than 5% of the anhydrous weight of the sodium chlorite. Pelletized sodium chlorite can be used to produce chlorine dioxide gas by passing a dilute mixture of chlorine gas and an inert gas through a bed of the pellets.

****!!!!****!!!!**** {CDG Environmental} The present invention is for extremely pure solutions of chlorine dioxide, methods for making such solutions and to compositions and methods for storing, shipping and using such solutions. " " the vapor pressure of chlorine dioxide gas above aqueous solutions of the gas as a function of temperature and concentration" "Chlorine dioxide solutions can deteriorate in by chemical degradation into chlorine, oxygen, chlorite, chlorate, or other decomposition products.. these decomposition reactions either do not occur or occur at very slow rates in solutions made of pure water and ultra-pure chlorine dioxide." **** "salt substantially increases the rate of chlorine dioxide decomposition in solution" "rate of concentration loss through the walls of an HDPE 55 gallon drum ... is negligible compared to the concentration decay due to other factors." **!!** " *Such containers, prior to use, can be pre-treated by filling with a pre-treatment solution containing chlorine dioxide or with dilute chlorine dioxide gas prior to filling with solution. This saturates the walls with chlorine dioxide and greatly slows initial chlorine dioxide losses." *** "After an initial rapid rate of loss, the solution in PET bottles is almost as stable as that stored in glass" "There is no statistically significant difference in the stability of the solutions at different temperatures and salt concentrations for temperatures of less than about 25° C." "Chlorine dioxide solutions made by reacting sodium chlorite with chlorine in aqueous solution, which produces high concentrations of sodium chloride, are much less stable than solutions made using pure chlorine dioxide and pure water."

Key Difference - Sodium Chlorite vs Sodium Hypochlorite   Sodium chlorite and sodium hypochlorite are common sodium salts used in industries. Both these co

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"Sodium chlorite will withstand considerable rough handling is it is free from organic matter. However, in contact with clothing, sawdust, flour, brooms, etc., the mixture is extremely sensitive to heat, friction or impact, and will ignite. Diaphragm pumps rather than piston pumps should be used for sodium chlorite solution. Spilled sodium chlorite requires special handling described in Dyox bulletin"

****!!!!****!!!!**** "The formation of chlorite increases with increasing of pH value whereas the formation of chlorate increases with decreasing the pH value, and the chloride ion is increased at a pH value below 3.4. The chlorite (ClO2–) exists as inert at above the ph 7. On the other hand this compound is very active below pH 7. However, the most efficient bleaching and maximum brightness are obtained in the first ClO2 stage (D0) at a pH level of about 3.5 – 4.0 while it is obtained in the second ClO2 stage (D1) at pH of 5.5 to 6. Normally, the pH varies from 7 to 3.5. So, less chlorine dioxide bleach is required for low pH than for high pH bleaching, but the temperature and retention time should be increased to speed up the reaction rate. At a lower pH (below 3.0) ClO2 can produced organic chlorine compounds which is not environment friendly. It is possible to take advantage of the chlorite with maintaining a rapid rate of bleaching by keeping the pH level high at starting position and then lower. Corrosion is kept under control by using tile lined or acid proof brick towers and plastic-lined or ceramic pipe. The residual ClO2 can create toxic fumes and corrosion at subsequent washing step. Therefore, SO2 or NaOH is used at the bottom of the tower to neutralizing it so that can be reduced corrosion and eliminated toxic fumes." "To eliminate explosion, the chlorine dioxide bleach should protect from uv light, keep lower concentration, uncontaminated and cool. Moreover, to reduce consumption pH would to be controlled carefully."

"We have studied the effects of chlorine dioxide fumigation on the reliability of electronic equipment using personal computers as examples of current commercial systems. Unit and subunit failure were objectively defined by standard commercial software. After the initial one-day exposures to the fumigation conditions, the systems were tested..."

"Of the oxidizing biocides, chlorine dioxide is the most selective oxidant. Ozone and chlorine are much more reactive than chlorine dioxide, and they will be consumed by most organic compounds. Chlorine dioxide, however, reacts only with reduced sulfur compounds, secondary and tertiary amines, and some other highly reduced and reactive organic compounds. A more stable residue can therefore be achieved with chlorine dioxide at much lower doses than when using either chlorine or ozone. Generated properly, chlorine dioxide can be used more effectively than ozone or chlorine in cases of higher organic loading because of its selectivity.:

This paper focuses on the connector failures due to decontamination and the associated failure mechanisms.

"The reaction between hydrogen peroxide and sodium chlorate in presence of aqueous sulfuric acid was studied at various temperatures and molar concentrations of hydrogen peroxide, chlorate and sulfuric acid. "

****!!!!**** "an unusually detailed quantitative mechanism for the complex reactions that occur in mixtures of chlorine species and organic substrates, particularly when the strong oxidant chlorite is employed. Kinetic control of the reaction is achieved by the addition of chlorine dioxide to the reaction mixture, thereby eliminating a substantial induction period observed when chlorite is used alone. The epoxidation agent is identified as chlorine dioxide, which is continually formed by the reaction of chlorite with hypochlorous acid that results from ClO produced by the epoxidation reaction. The overall stoichiometry is the result of two competing chain reactions in which the reactive intermediate ClO reacts with either chlorine dioxide or chlorite ion to produce hypochlorous acid and chlorate or chloride, respectively. At high chlorite ion concentrations, HOCl is rapidly eliminated by reaction with chlorite, minimizing side reactions between HOCl and Cl2 with the starting material. Epoxide selectivity (90% under optimal conditions) is accurately predicted by the kinetic model"

(2014)

****!!!!**** (2019) {Instructions (some of which probably need changes/corrections) for many uses. Also, lists of pathogens affected, with linked studies.} Vapor for Disinfection & Mold Elimination: 1 Gram Chlorine Dioxide per 1 square feet (w/10’ ceilings) [Researcher calcs: (0.28 m3). =3,571 mg/m3=1,275 ppmV in air], 3 to 24 hours – depending on issue severity of issue *****Concentrations to use for many applications****chart below shows how well ClO2 performs against alternatives. (other disinfectants)** Pathogens lisr with studies references **RECOMMENDED SPECIFICATIONS FOR CONTAINERS USED WITH CLO2 PRODUCTS...wear a NOISH/MSHA-approved respirator under the following conditions..." "Initial or remedial treatment... DECORATIVE AND ORNAMENTAL FOUNTAINS... Achieve a 5 ppm solution RESIDUAL concentration" "Continuous treatment... between 0.25 ppm and 0.5ppm"

{Chlorine dioxide, chlorite, chlorate, etc} "Chlorine dioxide disinfection byproducts: chlorate, chlorite. Health effects: Reduced ability of red blood cells to carry O2. Anemia and nervous system effects (for infants and young children)."

"Chlorine Dioxide is introduced to the pulp in the D0 tower where it reacts for approximately 1 hour. This fi rst stage chemical reaction removes most of the lignin binding agents in the pulp without destroying the carbohydrates, which would weaken the fi nal product. pH is maintained at a fairly low value (approx 2 - 4 pH) to insure a rapid chemical reaction. A higher pH level would consume more ClO2 for a given degree of bleaching. Temperatures can vary between 45 to 85°C (113 to 185°F)."

**** (2020) " ClO2 is produced on site in concentrations of... 8 to 12 thousand parts per million (ppm)" "Fortunately, ClO2 gas is self-alerting presenting a faint odor of bleach or chlorine at 0.1 ppm levels or less, thus necessitating area evacuation or use of respiratory protection. Based on ERPG data, such low-level exposure to ClO2 gas is not life-threatening. In fact, more recent studies indicate that ClO2 gas at low levels, well below the TWA17 of 0.1 ppm, could be useful as an antimicrobial in the presence of humans to mitigate and/ or prevent viral infection and possibly other related respiratory tract infections... ClO2 gas could be used in places such as hospitals, clinics, offices, hotels, schools and airport buildings without interrupting normal activities."

****!!!!**** (1943) {Note: Air sanitizers using glycol can be easily registered with EPA using basic data. Other substances require more data submission.} "The killing process was found to be more effective when both the total number of air-borne droplets and the number of organisms in the bacterial suspension are small. A temperature below 80°F. and an atmospheric relative humidity between 45 and 70 per cent were found to constitute the most favorable conditions for the lethal action of the vapor. Experiments were performed to test the bactericidal efficiency of propylene glycol vapor in both small and large enclosed spaces. These studies revealed that equally marked bactericidal action is obtained when propylene glycol is dispersed in an 800 cubic foot room as occurs in chambers of 2 cubic foot capacity. The susceptibility to vapor action of bacteria re-suspended in saliva was just as great as when broth was used as the suspending medium. Both partially and completely dehydrated bacteria also succumbed to the effects of the vapor. However, when unsterile dust collected from inhabited rooms was dispersed into the air, little reduction of the natural microbic population contained in this material was observed."