Chemical & Biological Dynamics

(2006).

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"There was no further oxidation past cysteic acid, and there was no evidence of sulfate formation which would have indicated the cleavage of the carbon−sulfur bond. The reaction is oligooscillatory in chlorine dioxide formation. In conditions of excess oxidant, the reaction is characterized by a short induction period followed by a rapid and autocatalytic formation of chlorine dioxide. Chlorine dioxide is formed by the reaction of intermediate HOCl with the excess chlorite:  2ClO2- + 2HOCl + H+ → 2ClO2(aq) + Cl- + H2O. Oligooscillations observed in chlorine dioxide formation result from the competition between this pure oxyhalogen reaction and reactions that consume chlorine dioxide. The rate of the reaction of chlorine dioxide with cysteine and its metabolites is fast and is of comparable magnitude with the reactions that form chlorine dioxide. The reaction of chlorine dioxide with l-cysteine is first order in both oxidant and substrate, retarded by acid, and has a lower-limit bimolecular rate constant of 405 ± 50 M-1 s-1, while for the reaction with l-cysteinesulfinic acid the rate constant is 210 ± 15 M-1 s-1. It would appear that the existence of a zwitterion on the asymmetric carbon atom precludes the formation of N-chloramines as has been observed with taurine and aminomethanesulfonic acid. The mechanism for the reaction is satisfactorily described by a network of 28 elementary reactions which include autocatalysis by HOCl."

"Redox reactions of simple inorganic species exhibit an amazingly rich variety of complex kinetic phenomena."

"The chlorine−dioxide-tetrathionate reaction was studied spectrophotometrically in the pH range 4.55−5.55 at 25.0 ± 0.2 °C and 0.5 M ionic strength adjusted with sodium acetate as a buffer component."

"egardless of the food product, nearly all radioactive residue was present in edible tissues as chloride ions; the chlorite ion was present only in egg-rinse water. Small amounts (10% or less) of radioactivity were present as chlorate ions, which would be a useful marker compound for chlorine dioxide sanitation."

***!!!!*** "...overview of the inactivation kinetics and mechanisms of ClO2 with viruses. The inactivation efficiencies vary greatly among different virus species. The inactivation rates for different serotypes within a family of viruses can differ by over 284%. Generally, to achieve a 4-log removal, the exposure doses, also being referred to as Ct values ...vary in the range of 0.06–10 mg L−1 min. Inactivation kinetics of viruses show two phases: an initial rapid inactivation phase followed by a tailing phase. Inactivation rates of viruses increase as pH or temperature increases, but show different trends with increasing concentrations of dissolved organic matter (DOM). Both damages in viral proteins and in the 5′ noncoding region within the genome contribute to virus inactivation upon ClO2 disinfection."

Ingredients: "3.35% purified sodium chlorite or 2.00-2.10% available chlorine dioxide + oxychloro species"

****!!!!!****!!!!**** pg 31. "Using a proprietary technique, Oxine® solution is buffered at a pH between 8.0 – 8.5. Most other chlorite products are buffered at a pH of 11‐12. Therefore, the higher pKa acids perform poorly with tech‐grade products" "The intermediates (such as HClO2) generated in this reaction, act as a reservoir for replenishing ClO2 as it gets used up in the system" "Oxine® is much more potent than tech-grade sodium chlorite when tested on pseudomonas aeruginosa, staphylococcus aureus and saccharomyces cerevisiae, which serve as indicator organisms for an array of bacteria and fungi." "test strips are not the best way to measure free ClO2 in this range. Iodometric drop-titration or spectrophotometric methods are the best ways to measure free ClO2 concentrations." "dozens of regulations were submitted by BCI to FDA, EPA, USDA, FSIS, NSF and OMRI, to expand the use of this chemistry in direct-food and other applications. Millions of dollars were spent on toxicology and efficacy studies to ensure that the Oxine product delivers all its label claims." "Whereas solids may seem convenient for use, there are disadvantages...1. Solid sodium chlorite...is mixed with stabilizers to minimize its fire hazard. Stabilizers that are at least 20% (by total weight) of the chlorite salt consist of various salts, such as calcium carbonate, that can shield bacteria from antimicrobial activity. Liquid solutions of chlorite, on the other hand, do not contain substantial amounts of stabilizers. 2. Homogeneous dissolution of tablets or flakes require extra care; otherwise the concentration gradients are formed, causing inconsistent activation of product. 3. The biggest disadvantage with these products is the cost factor... [One specific solid product is} at least 500% more expensive than Oxine."

Aseptrol slow-release chlorine dioxide (in liquid). "30ppm chlorine dioxide to be mycobactericidal in 60 seconds and sporicidal in 1 to 5 minutes." "...this organic material did not affect the microbicidal properties of chlorine and chlorine dioxide. This is contrary to the finding of Isomoto who showed that organic material can compromise the efficacy of chlorinated compounds. " {Financial & time savings--Although manufacturers recommend daily prep, solution was found effective 27 days} "A study has shown the safety of chlorine dioxide on gingival fibroblasts (Nishikiori et al., 2008)"

{Many useful answers for practical application processes for chlorine dioxide fumigation}

***!!!!***!!!!*** {EXTREMELY VALUABLE summaries of dynamics of chlorine dioxide as reported from many scientific studies} "Apart from sanitizing the surface of fruits and vegetables using ClO2gas, hard surfaces like belts, metal conveyors and pads are treated with ClO2 foam as they are also one of the important transmitters of contamination during packaging or processing of fruits and vegetables (13)." "Since ClO2 gas is highly soluble in water, its inactivation properties aresimilar to the aqueous solution (58), (59). The kill mechanism of ClO2 is by interfering with protein synthesis(14), and by reacting with proteins and lipids, thereby increasing the permeability of the outer membrane(60), which causes loss of intracellular ions (61)and major destruction. This theory of kill mechanism of ClO2 gas was observed in several studies. Han et al. (17) determined that when Listeriamonocytogenes and E. coli O157:H7were treated with higher gas concentration (1.8 and 3 mg/l),their resistance was similar. However, at lower gas concentration and short treatment time (0.6 mg/l for 15 min), L. monocytogenes was more sensitive than E. coli O157:H7. The difference in resistance between Gram-positive and Gram-negative bacteria, is due to the difference in cell wall structure and components"

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"Chlorite is enriched in iron concentrate during strong magnetic separation, which reduces the grade of iron concentrate. Despite these facts, the reports of separation of chlorite and weak magnetic iron ore minerals have seldom been reported, especially in the aspects of mechanism of the interaction between the reagents and minerals."

The mole ratio r(r=[I−]0/[ClO2]0) has great influence on ClO2-I−-H2SO4 closed reaction system. By changing the initiate concentration of potassium iodide, the curve of absorbance along with the reaction time was obtained at 350 nm and 297 nm for triiodide ion, and 460 nm for iodine. The changing point of the absorbance curve's shape locates at r=6.00. For the reaction of ClO2-I− in the absence of H2SO4, the curve of absorbance along with the reaction time can be obtained at 350 nm for triiodide ion, 460 nm for iodine. The mole ratio r is equal to 1.00 is the changing point of the curve's sh...

In order to study the chemical oscillatory behavior and mechanism of a new chlorine dioxide-iodide ion-methyl acetoacetate reaction system, a series of experiments were done by using UV-Vis and online FTIR spectrophotometric method. The initial concentrations of methyl acetoacetate, chlorine dioxide, potassium iodide, and sulfuric acid and the pH value have great influence on the oscillation observed at wavelength of 289 nm. There is a preoscillatory or induction period, and the amplitude and the number of oscillations are associated with the initial concentration of reactants. The equation...

D7 delivers a powerful disinfectant, cleaner, and deodorizer, making it practical for food production environments, public safety, and military situations.

"It appears that the mechanism of action of Oxine® is to penetrate the spore, possibly through chemical attack of the spore coat layers, and to dissolve the spore core, causing collapse of the spore structure."

***** 2020 "Chlorine dioxide (ClO2) has emerged as a promising alternative to free chlorine for water disinfection and/or pre-oxidation due to its reduced yields of chlorinated disinfection byproducts...""ClO2− serves as a radical generator, a light competitor and a radical/ozone scavenger. ClO2− reduces the concentrations of radicals and ozone in the UV/chlorine process. UV photolysis of ClO2− only generates HO• under drinking water relevant conditions. ClO3− is mainly generated from oxidation of ClO2− by HO• in the UV/chlorine process."

***** 2020 "Chlorine dioxide (ClO2) has emerged as a promising alternative to free chlorine for water disinfection and/or pre-oxidation due to its reduced yields of chlorinated disinfection byproducts. ClO2 decomposes to form chlorite (ClO2-), which influences the following advanced oxidation processes (AOPs) for micropollutant abatement in drinking water. This study aims at investigating the effects of ClO2- on the concentrations of reactive species (e.g., radicals and ozone) and on the formation of chlorate in the UV/chlorine AOP. Results showed that the concentration of ClO· in the UV/chlorine process remarkably decreased by 98.20-100.00% in the presence of ClO2- at concentration of 0.1-1.0 mg·L-1 as NaClO2. The concentrations of HO· and ozone decreased by 42.71-65.42% and by 22.02-64.31%, respectively, while the concentration of Cl· was less affected (i.e., 31.00-36.21% reduction). The overall concentrations of the reactive species were differentially impacted by ClO2-'s multiple roles in the process. UV photolysis of ClO2- generated HO· but not Cl·, ClO· or ozone under the drinking water relevant conditions. ClO2- also competed with chlorine for UV photons but this effect was minor (< 1.0%). The radicals/ozone scavenging by ClO2- outcompeted the above two to lead to the overall decreasing concentrations of the reactive species, in consistency with the kinetic model predicted trends. ClO2- reacted with radicals and ozone to form chlorate (ClO3-) but not perchlorate (ClO4-). HO· played a dominant role in ClO3- formation."

A method for producing chlorine dioxide by activating zeolite crystals (which have been impregnated with metal chlorite such as sodium chlorite, and optionally also a water-retaining substance such as magnesium sulfate, potassium chloride, potassium hydroxide, or calcium chloride) with excess protons, or activating an aqueous solution of metal chlorite and such a water-retaining substance with excess protons. Proton generating species useful for the activation are acids such as acetic, phosphoric, and citric acid, and metal salts such as ferric chloride, ferric sulfate, ZnSO 4 , ZnCl 2 , Co...

***!!!!***!!!!** 2020. "Many of the innovations stop short of evaluating actual yield, practical feasibility, or basic chemistry of the technology. In this study, our aim was to evaluate ClO2 precursors, sodium chlorite and citric acid, under disparate but applicable conditions." "low temperatures reduced ClO2 reported yield. Peak rates of production at 18 °C were estimated to be 3.51 mg/h, 3.83 mg/h, and 4.78 mg/h for sample ID 1, 2, and 3, respectively. Modeling the rate of production indicated that sample IDs had significantly different rates of production... Under 2 °C, these rates were 15 fold. We also determined that the reservoir placement could affect reported ClO2 concentrations. At the same time, ClO2 was able to reduce all three pathogens in 6-log10 CFU/carrier and performed significantly better at refrigeration temperature compared to room temperature."

***!!!!*** "Formulations for the sustained release of chlorine dioxide (ClO2) gas were developed, and their gas-producing profiles and antimicrobial effects... were evaluated" "Sodium chlorite (NaClO2) and citric acid were used to generate ClO2 gas, and the generation rate and maximum ClO2 gas concentration were controlled using diatomaceous earth (DE) and calcium chloride (CaCl2). "

"Its efficacy is largely not affected by pH and organic matter and it does no react with nitrogen compounds to form chloramines. The most widely accepted antimicrobial mechanism of ClO2 is damage to protein synthesis and increased permeability of the outer cell membrane. ClO2 gas may be more effective for inactivation of foodborne pathogens than aqueous ClO2 due to its penetration ability. Also, ClO2 gas could be applied for microbial control during transportation and storage of food." "The specific objectives of this study were, (ⅰ) to investigate the effect of relative humidity, surface characteristics of samples, and temperature on the antimicrobial efficacy of ClO2 gas... on produce and food contact surfaces, (ⅱ) evaluate the antimicrobial effects of the combination treatment of ClO2 gas with ultraviolet (UV) radiation, aerosolized sanitizer, and dry heat against foodborne pathogens on produce and seeds, (ⅲ) develop portable sustained release formulation of ClO2 gas for field application." "Combined treatment of ClO2 gas (10 ppmv) and aerosolized PAA (80 ppm) for 20 min caused 5.36, 5.06, and 4.06 log reductions of E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively."