***** "test rig working in a flow-through mode similar to the disinfection procedures in waterworks, but under tightly defined conditions, including very short contact times. To quantify the influence of DOC, temperature and pH on the efficacy of two standard disinfectants, chlorine and chlorine dioxide, simulated use tests were systematically performed. This test rig enabled quantitative comparison of the reduction of four test organisms, two viruses and two bacteria, in response to disinfection. Chlorine was substantially more effective against Enterococcus faecium than chlorine dioxide whereas the latter was more effective against the bacteriophage MS2, especially at pH values of >7.5 at which chlorine efficacies already decline. Contrary to expectation, ***bacteria were not generally reduced more quickly than viruses.*** Overall, the results confirm a high efficacy of chlorine and chlorine dioxide, validating them as standard disinfectants for assessing the efficacy of new disinfectants"

{Water treatment, contact lens solution, etc} Contact Lens Solution: "(Regard™) using a combination of sodium chlorite (NaClO2; used to disinfect mains water) and trace amounts (100 ppm) of hydrogen peroxide (Atkins 2004). The peroxide stabilises the inherently unstable chlorine dioxide (ClO2) generated, and the combination is said to be effective against Gram-positive and Gram-negative bacteria, fungi and yeasts. Decomposition products are sodium chloride, water and oxygen. When lenses are removed from solution, the residual sodium chlorite decomposes readily into sodium chloride and oxygen. " "It is a powerful oxidant that disrupts protein synthesis, making it an efficient antimicrobial. However, penetration of biofilms can be challenging and chlorine dioxide can take months to achieve microbial control, can corrode pipework and readily decomposes, particularly in hot water, though higher concentrations can be used in the hot water supply.130,133,134 Concentrations of 0.5 mg/l are effective against planktonic and sessile Legionella in hot water systems. However, The Drinking Water Inspectorate advises a maximum of 0.5 mg/l chlorine dioxide in drinking water "

****!!!! "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 (mutiplying the concentration of ClO2 and contact time) 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."

The present invention provides for a stabilized solution containing a halogen containing compound which is effective as a sterilizing or disinfecting agent, and a stabilizing agent which suppresses the chemical dissociation of the halogen compound such that the sterilizing capability of the solution is maintained for extended periods of time relative to the solution without the stabilizing agent. The halogen containing compound is selected from the group consisting of chlorine dioxide, bromine oxide, bromine chloride, monochloroamine, bromic acid, iodine monochloride, iodine trichloride and iodine monobromide. The stabilizing agent is a compound having at least one accessible sulphur containing group selected from the group consisting of cyclamic acid, dimethyl sulphoxide, glyoxyl sodium bisulphite, potassium sorbate, sodium cyclamate, sodium metabisulphite, sodium oxalate, sodium sulphite, sodium thiosulphate and thioacetamide. Processes and kits for sterilizing or disinfecting water and objects utilizing the stabilized solutions are also provided by the present invention.

2003. Appendix B: "CT VALUES* FOR 4-LOG INACTIVATION OF VIRUSES BY CHLORINE DIOXIDE pH 6-9" "CT VALUES* FOR 3-LOG INACTIVATION OF GIARDIA CYSTS BY CHLORINE DIOXIDE"

"Table D-8. CT Values for Inactivation of GimYi” Cysts by Chlorine Dioxide...Table D-9. CT Values for Inactivation of Viruses by Chlorine Dioxide pH 6-9"

{Includes chart of critical levels for pathogens in water} "Shock treatment is recommended twice a year and usually requires a concentration of 20-50ppm chlorine dioxide be maintained for 12 hours, and then the irrigation system thoroughly rinsed before irrigation begins again, due to risk of phytotoxic effects with high concentrations. After shock treatment, a continuous treatment of 0.25ppm residual chlorine dioxide is usually sufficient to prevent regrowth of biofilm. " "The optimum chlorine dioxide range to treat biofilms and common plant pathogens is 0.25 to 3.3 ppm"

"Surprisingly, chlorine dioxide was not effective for As III oxidation. A three-fold stoichiometric dose of chlorine dioxide produced only 20 to 30 percent oxidation in 21 seconds and none thereafter. Even a 100-times stoichiometric dose produced only 76 percent oxidation in five minutes."

**** {Includes helpful illustration} "Chlorine dioxide's behaviour as an oxidising agent is quite dissimilar. Like ozone, the predominant oxidation reaction mechanism for chlorine dioxide proceeds through a process known as free radical electrophilic (i.e. electron-attracting) abstraction rather than by oxidative substitution or addition (as in chlorinating agents such as chlorine or hypochlorite). This means that chlorinated organic compounds such as THMs and HAAs are not produced as a result of disinfection using chlorine dioxide"

Pre-oxidation is commonly used to mitigate the formation of byproducts during post-disinfection. A comparative study of the impact of four pre-oxidants, ozone (O3), chlorine dioxide (ClO2), permanganate (Mn(vii)) and ferrate (Fe(vi)), on the formation of trihalomethanes (THMs), haloacetonitriles (HANs) and a

**** {Tested at 1 ppm and ph of 7 for 8 wks} "four different kinds of water pipes, two based on plastics, namely random polypropylene (PPR) and polyethylene of raised temperature (PERT/aluminum multilayer), and two made of metals, i.e., copper and galvanized steel, were put in a semi-closed system where ClO2 was dosed continuously. The semi-closed system allowed for the simulation of real ClO2 concentrations in common water distribution systems and to simulate the presence of pipes made with different materials from the source of water to the tap. Results show that ClO2 has a deep effect on all the materials tested (plastics and metals) and that severe damage occurs due to its strong oxidizing power in terms of surface chemical modification of metals and progressive cracking of plastics. These phenomena could in turn become an issue for the health and safety of drinking water due to progressive leakage of degraded products in the water."

****!!!!****"If you buy a 2% CLO2 product (Oxine), you are actually getting a 3.35% Sodium Chlorite in that jug or drum. It is essentially a 1.67 multiplier from the percentage of CLO2 that product claims." "Sodium Chlorite is widely used as a sanitizer and can be effective at inhibiting bacteria. It is important to know that chlorite solutions can carry anti-microbial claims listed as static or stasis by the EPA. That means chlorite solutions can inhibit or prevent bacteria growth of present organisms" [without necessarily destroying them] "we have found the liquid inorganic acids like LpH 100 work best and allow for less acid to be used with higher conversion to CLO2." "Contact time with your acid or ‘activator’ and pH of the working solution your acid is creating. Those two dynamics will determine how much Chlorine Dioxide you actually generate." "When using 5% stabilized CLO2 products like Pro Oxine after you achieve proper activation you will convert about 25% to 30% of that solution to CLO2. 70 to 75% of that solution will remain chlorite and be a part of your TOTAL working solution. The remaining sodium chlorite is important and will play a critical role in how well your product works over time." "Bio-Cide’s AANE [Automatic Activation Non Electric] system... to deliver product without ever having to mix products but allows for proper contact time and pH in your working solution to generate FREE CLO2 in your water system. The system is very easy to set up and can be used with any pump system you already have" "So you can essentially have 1.8 ppm TOTAL and .8 ppm FREE under the potable water claim approved by the EPA." " you never have to turn off your system to run other supportive care products or water soluble antibiotics. Since CLO2 is a ‘selective’ oxidizer it doesn’t seem to negatively affect these other products"

{Excellent chart of industrial uses} {Info on regulations for chlorine dioxide} "OxyChem technical sodium chlorite products"

****** "The most common method of generating ClO2 is through the reaction of chlorine gas with a solution of sodium chlorite. Theoretically, 1 lb of chlorine gas is required for each 2.6 lb of sodium chlorite. However, an excess of chlorine is often used to lower the pH to the required minimum of 3.5 and to drive the reaction to completion. Sodium hypochlorite can be used in place of the gaseous chlorine to generate chlorine dioxide. This process requires the addition of sulfuric or hydrochloric acid for pH control. Other methods used for chlorine dioxide generation include:..." "Complex organic molecules and ammonia are traditional chlorine-demand materials that do not react with chlorine dioxide. " "The chemical behavior and oxidation characteristics of aqueous chlorine dioxide are not well understood because of the difficulty in differentiating aqueous chlorine-containing species." "Chlorine dioxide consumed in water treatment reactions reverts to chlorite ions (ClO2-), chlorate ions (ClO3- ), and chloride ions (Cl -)." "As a gas, chlorine dioxide is more irritating and toxic than chlorine. Chlorine dioxide in air is detectable by odor at 14-17 ppm, irritating at 45 ppm, fatal in 44 min at 150 ppm, and rapidly fatal at 350 ppm. Concentrations greater than 14% in air can sustain a decomposition wave set off by an electric spark. The most common precursor for on-site generation of chlorine dioxide is also a hazardous material: liquid sodium chlorite. If allowed to dry, this powerful oxidizing agent forms a powdered residue that can ignite or explode if contacted by oxidizable materials. The hazardous nature of chlorine dioxide vapor and its precursor, and the volatility of aqueous solutions of chlorine dioxide, require caution in the design and operation of solution and feeding equipment."

****

"This book reports on the research done to determine whether East Bay Municipal Utility District, CA, can replace Cl2 with ClO2 for biofouling suppression in the aqueduct and in open-air treatment basins, with the aim of reducing THM and HAA concentrations without sacrificing treatment performance associated with the use of Cl2. "

"Waters bearing high total antioxidant capacity tended to generate more ClO 2⁻ at equivalent ClO 2 exposure, but the prediction in natural water should be conservative."

"Cyanobacteria (blue-green algae) are known producers of cytotoxic, hepatotoxic, and neurotoxic compounds with severe acute and chronic effects on vertebrates. Successful removal of these toxins in drinking water treatment is therefore of importance for public health. "

"Minimizing the inorganic by-products chlorite ion and chlorate ion in drinking water treated with chlorine dioxide is important if ClO₂ is to remain a viable alternative in potable water treatment. The use of sulfur dioxide-sulfite ion chemistry to quantitatively remove chlorite ion to below the 0.1-mg/L level is described, along with the use of free chlorine to remove the sulfur dioxide-sulfite ion. The stoichiometry and the rate law are described for pH values of 5.5 to 8.5 so that the chemistry can be applied directly in existing drinking water treatment facilities."

****!!!!****** {Includes equations for predicting impact of variables in determining quantity of byproducts} "At 20oC, pH 7, 70-80% of chlorine dioxideinjected was converted to chlorite and 0-10% of that was transformed into chlorate within 120 min with 2.91 mg/Lof DOC. The amount of chlorite formed also increased when pH and temperature increased. As DOC content increased,the residual chlorine dioxide decreased but the amount of chlorite and chlorate were increased. These experimentsrevealed that chlorate was a dominant by-product under UV irradiation."

****!!!!****!!!! {Materials suitable for Chlorine Dioxide containers} "Construction should be of dark or opaque/UV-blocking (preferred) oxidation-resistant plastic or glass. Some materials recommended include: -High Density Polyethylene (HDPE)- Polypropylene (PP)- Polyethylene Terephthalate (PET) (PETE)- Polyvinyl Chloride (PVC)- Polycarbonate (PC)- Glass (UV-blocking preferred)- Gasket materials; silicone, viton or EPDM" "DECORATIVE AND ORNAMENTAL FOUNTAINS 5 ppm residual chlorine dioxide level. Circulate water in normal operation of the system.... Repeat daily until desired results are achieved." "Selective Micro® Chlorine Dioxide Test Strips"

****!!!!!****!!!!**** 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."

***** 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."

"...The microporous membrane suction filtration method and animal test method were used to observe the sterilization effect and toxicology. As a result, the chlorine dioxide produced by the Juyuan brand chlorine dioxide generator containing 0.5mg/L of chlorine dioxide, the Sadi brand stable chlorine dioxide and the Siriman disinfectant were used for 1min, 5min and 10min, respectively. The killing rate of Escherichia coli in water reached 100%. The pH value of water above 7.0 has a slight influence on the sterilization effect of the three kinds of chlorine dioxide; organic matter affects the sterilization effect of chlorine dioxide. The oral toxicity test of the three disinfectants is LD50 500 mg/kg (body weight); the accumulation coefficient K 5 is weak accumulative toxicity; the mouse bone marrow polychromatic erythrocyte micronucleus test is negative. The results show that the three chlorine dioxide disinfectants have a strong killing effect on E. coli in the water, and the toxicity is low "

The oxidation of N-nitrosodimethylamine (NDMA) precursors during water treatment was investigated using ozone and chlorine dioxide (ClO2). Second-order rate constants for the reactions of model NDMA precursors (dimethylamine (DMA) and 7 tertiary amines) with ozone (kapp at pH 7 = 2.4 × 10-1 to 2.3 × 109 M-1 s-1), ClO2 (kapp at pH 7 = 6.7 × 10-3 to 3.0 × 107 M-1 s-1), and hydroxyl radical (•OH) (kapp at pH 7 = 6.2 × 107 to 1.4 × 1010 M-1 s-1) were determined, which showed that the selected NDMA precursors, with the exception of dimethylformamide (DMFA) can be completely transformed via their...

"Effects of water characteristics, reaction time, temperature, bromide and iodide ion concentrations, oxidant doses, and pH on formation of iodinated trihalomethanes (I-THM) during oxidation of iodide-containing water with chlorine dioxide (ClO2)"