Chemical & Biological Dynamics

****!!!!**** The focus of this paper is on chlorine dioxide removal from air to each of 24 different indoor materials... Deposition velocities and reaction probabilities varied over approximately 2 orders of magnitude across all materials. For most materials, deposition velocity decreased significantly over a 16-h disinfection period; that is, materials became smaller sinks for chlorine dioxide with time. Four materials (office partition, ceiling tile, medium density fiberboard, and gypsum wallboard) accounted for the most short- and long-term consumption of chlorine dioxide. Deposition velocity was observed to be a strong function of chlorine dioxide inlet concentration, suggesting the potential importance of chemical reactions on or within test materials."

{Free download}

Adsorbable organic halogens (AOX) are formed in pulp bleaching as a result of the reaction of residual lignin with chlorine dioxide. The natural structure of lignin is very complex and it tends to be damaged by various extraction methods. All the factors ...

(2001)

This article discusses how dosing chlorine and chlorine dioxide concurrently provides excellent disinfection inactivation and limits chlorite formation. This was done when Aurora (Colorado) Water's 8...

"determine the effect of granular activated carbon (GAC) filtration and sulfur-based reducing agents on chlorite and chlorate ions in water. It is concluded that neither GAC filtration nor sulfur-based reduction is a feasible means of removing chlorine dioxide by-products."

****!!!!**** {Data in tables is based on limited sources} "A review of data from Hoff (1986) indicates that the disinfection efficiency of chlorine dioxide for bacteria and viruses increases approximately 2 to 3 gold as pH increases from 7 to 9." "pg 378 Table of CT Values for Inactivation of Giardia Cysts by Chlorine Dioxide in pH 6-9" "[page 379] Table of CT Values for Inactivation of Viruses by Chlorine Dioxide in pH 6-9"

****!!!!****!!!!**** " Nearly all AZTD samples completely decontaminated • Greater than 6 LR for topsoil at 1 cm depth, 2 hour, both RH levels • 2 cm topsoil much more difficult to decon" "Aqueous ClO2 completely ineffective ( 0.5 LR) at most robust test conditions (4000 ppm, 2 hr contact Time, 4 spray applications)"

"A new disinfectant is super-oxidized water (SOW) with a wide antimicrobial effect, which contains HClO, chlorate (I) anion, chlorine, chlorine dioxide, hydrogen peroxide, and ozone. SOW achieves effective disinfection within a short time (5–10 minutes) comparable to sterilization processes and is safe to environment, medical personnel, and patients. The disadvantages of SOW are that it has to be produced at the site of use and the antimicrobial effect is reduced in the presence of organic substances" "Oxidizing compounds: H2O2, HClO, ClO2, and peracetic acid cause oxidation of thiol groups (̶ SH) in cysteine residues, which form disulfide bridges that determine the structure and function of proteins. Because cysteine residues are located at the active sites of many bacterial enzymes, their oxidation by oxidizing compounds leads to inactivation."

****!!!! "our four signature solutions: Verisan, Virusan, PetSan and VeggieSan." "Reg no. 9150-3 [which is Carnebon 200, and may or may not be one of this company's products]"

"Clathrates trap gaseous chlorine dioxide to provide a dry solid material that is stable and easy to use and handle. Stable formulations of gaseous chlorine dioxide are useful as disinfectants."

****!!!! "Adding salt to the aqueous solution used to produce sterilant allows humidity control, which improves kill of bacterial spores" "• Indicator to show ClO2 is present: • Indicator is printed on or attached to inside of pouch • Changes color on exposure to ClO2" "Reversible indicator on outside of sterilizer bag to show when unit is too cold and should be warmed for correct functioning" "To eliminate bacterial spores, it is highly desirable to control the humidity during sterilization to 70 to 95%, preferably 90 to 95%. Adding NaCl to the NaClO2 solution lowers the humidity of the gases produced from 100% to the desired range."

Slide 1 Cl2 vs. ClO2

"Wei et al. reported that in radiotherapy ward, the action time of peroxyacetic acid is 1 h, and of chlorine dioxide is 30–60 min" "chlorine dioxide, and liquid chlorine disinfections are commonly used for hospital wastewater disinfection during COVID-19 pandemic"

****!!!!****!!!!

Chlorine dioxide (ClO2) is often used as an oxidant to remove taste, odor and color during water treatment. Due to the concerns of the chlorite format…

"in-depth analysis of the effects of UV wavelength on the simultaneous removal of ClO2- and OMPs in water."

"sequential ClO2-UV/chlorine process was effective for the removal of 12 micropollutants. ClO2 pre-treatment reduced the formation of disinfect byproducts (DBPs) in the UV/chlorine process. Compared to the UV/chlorine process, ClO2 pre-treatment (1.0 mg L-1) decreased the formation of the 6 DBPs by 25.1-72.2%; and decreased the formation potential of the 6 DBPs by 13.9-51.8%. Moreover, ClO2 pre-treatment reduced the concentration of total organic chlorine by 19.8%. ClO2 pre-treatment affected the UV/chlorine process in different ways. Firstly, ClO2 pre-treatment generated chlorite, which dominantly served as a scavenger of chlorine radical (Cl) and hydroxyl radical (HO). Secondly, ClO2 pre-treatment decreased the reactivity of natural organic matter (NOM) towards radicals. Finally, ClO2 pre-treatment altered the properties of NOM, in terms of reducing the electron-donating capacity and aromaticity of NOM (SUVA254), and slightly reducing the average molecular weight of NOM."

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 findings improved the fundamental understanding on micropollutant abatement and inorganic byproduct formation by the UV/chlorine process and other AOPs in ClO2--containing water.

Chlorine dioxide when used as an effective disinfectant forms undesirable disinfection by-products, i.e. chlorite and chlorate ions.

"What hazardous chemicals are used to generate chlorine dioxide? Most processes used today use methanol, sodium chlorate, and sulfuric acid, which are all hazardous" "Methanol is highly flammable but the flame is almost invisible in daylight. It is highly toxic if it gets absorbed through skin, ingested, or inhaled." "Sodium chlorate is only a mild skin irritant, but small quantities (5-10 g) can be fatal if ingested." "Sulfuric acid is highly corrosive so it will cause severe chemical burns if it contacts your skin or eyes." "Chlorine dioxide storage poses a significant environmental and safety threat. There are several features needed for the safe storage of chlorine dioxide. The tank should be insulated to keep chlorine dioxide cool. An explosion relief lid on the top of the tank in case an explosion occurs. Sweep air is added to the top of the storage tank to dilute the concentration of vent gas sent to the scrubber. A floating cover in the tank can reduce the amount of ClO2 gas present at the top of the tank. This can allow higher storage concentrations which can reduce tank size, energy for generation and cooling, and the amount of steam needed in the bleach plant."

{Visit https://goo.gl/7jy751 to view the full video} "There are several features needed for the safe storage of chlorine dioxide. The tank should be insulated to keep chlorine dioxide cool. An explosion relief lid on the top of the tank in case an explosion occurs. Sweep air is added to the top of the storage tank to dilute the concentration of vent gas sent to the scrubber. A floating cover in the tank can reduce the amount of ClO2 gas present at the top of the tank. This can allow higher storage concentrations which can reduce tank size, energy for generation and cooling, and the amount of steam needed in the bleach plant."

"purification process of purifying Philippine clams in the oxygenated state with 4 times of disinfected seawater...) was explored, and the water was changed once for 8 hours, and the purification time was 24 hours. The pilot test of the process can reduce the number of E. coli population in the Philippine Hazai intestine... and the sterilization rate reaches about 95%, the sand content is reduced from 65mg/100g to 23mg/100g, and the volatile salt-based nitrogen rises from 3.8mg/100g to 5.8mg/100g," "phenolic compounds denature proteins and make microorganisms inactive, and also different from chlorine biochlorination and inactivity. When it comes into contact with microorganisms, it releases new ecological oxygen and hypochlorous acid molecules and produces a powerful bactericidal and disinfection effect. This strong oxidation effect makes the amino acids in microorganisms oxidize and decompose, so as to inhibit their growth and kill them. Its residues water, trace chloride, carbon dioxide, organic sugar and other non-toxic and harmless substances." "According to the experimental results of Chen Youlin [2], the mass fraction of chlorine dioxide only needs to be 10× 10-6 action for 5 minutes to completely kill E. coli, mass fraction 10× 10-6 action to completely kill Staphylococcus aureus, mass fraction 100× 10-6 action 10min to kill spore bacteria, mass fraction 500× 10-6 for 2min to destroy hepatitis B virus (HBSAG); Chlorine dioxide can also have a special decomposition effect on cyanide, etc"

****!!!!****!!!!**** {List of their recommended specific chlorine dioxide concentrations and contact times for disinfection against plague/epidemic diseases}

The promulgation of odor control rules, increasing public concerns, and... (EPA) air regulations in nonattainment zones necessitates the remediation of a wide range of volatile organic compounds (VOCs) generated by the rendering industry." "wet scrubber analysis using chlorine dioxide (ClO2) as the oxidizing agent indicated that close to 100% of the methanethiol was removed from the gas phase, but removal efficiencies ranged from 20 to 80% for the aldehydes and hydrocarbons and from 23 to 64% for total VOCs"

(1950)

(1958)