Chemical & Biological Dynamics

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

*****!!!!!!**** {Links to many highly valuable Chinese studies}

****!!****"So far, it has been found that chlorine dioxide only reacts with a few reducing amino acids. As early as 1967, Benarde et al. used the changes of OD280 and paper chromatography to fail to prove that chlorine dioxide is associated with proteins and free amino acids (histidine, aspartic acid, phenylalanine, arginine, proline and proline). Leucine) reacts [9]. However, Noss et al. mixed chlorine dioxide with 19 kinds of amino acids under in vitro conditions, and found that 6 kinds of amino acids showed reactivity with chlorine dioxide (expressed as chlorine dioxide consumption), namely proline, Histidine, Cysteine, Tyrosine, Tryptophan"

"In recent years, chlorine dioxide gas is directly dissolved in water. By adding stabilizers, it becomes a product that can be used directly without activation. Although the risk of unsafety is removed and the convenience of use is also brought, the addition of stabilizers reduces the purity of the solution. Restricted the use of products in higher-end areas. Adopting nanospheres to directly absorb chlorine dioxide gas, and then release it through control, not only without any additives and activation, but also the volume..."

"This paper analyzes the existence of ClO_2 and carbonates in the so-called "stable chlorine dioxide" solution prepared with stabilizers H_2O_2, Na_2CO_3 and ClO_2. At the same time, the "stable chlorine dioxide" is analyzed. The thermal stability, the influencing factors of acid activation and the bactericidal effect were studied, and compared with pure NaClO_2 and ClO_2. The results showed that the ClO_2 in the "stable chlorine dioxide" solution is based on chlorite ClO_2~- The carbonate is in the form of bicarbonate. It is also proved by theoretical analysis that during the preparation of the "stable chlorine dioxide" solution, ClO_2 undergoes redox and proton transfer reactions with H_2O_2 and Na_2CO_3, resulting in the formation of subchlorine Salt ClO_2~- and bicarbonate HCO_3~-, and O_2 is released. Therefore, it is considered that the "stable dioxygen than chlorine" solution..."

****!!!!**** "The effect of the photodegradation rate under different light sources from fast to slow is 354nm ultraviolet light, natural light, 257nm ultraviolet light, fluorescence, and darkroom, indicating that the wavelength that acts on the photodegradation of gas ClO_2 is ultraviolet light near the visible light region and Visible light with a shorter wavelength; the concentration of ClO_2 in the darkroom is basically unchanged. In the range of 15～25℃, temperature has almost no effect on the degradation rate of ClO_2. Under natural light, when the gas ClO_2 is at a higher concentration (100-200mg/L), the time required for the gas ClO_2 to decay to half of the initial concentration is between 50-60min; when the concentration is low (≤20mg/L), only It takes 10 to 20 minutes to basically decompose. (2) The theoretical study of the spatial configuration of oxychloride is based on the B3LYP/6-311+G(3df) basis set. The spatial configuration of oxychloride is studied, and the bond length, bond angle and energy of the oxychloride molecule are calculated. And vibration frequency." "Cl-Cl bond is not found in the stable molecular structure of oxychloride compounds. The chemical bond between the two monochlorides that make up the dichloride is on its two reaction center atoms, and determines the structure of the dichloride. (3) Research on the decomposition products and decomposition mechanism of gas ClO_2 combined with experimental analysis and theoretical calculation results, it is found that the final products of the photodegradation process of gas ClO_2 are Cl_2, Cl_2O_4 and Cl_2O_6, and the intermediate product is Cl_2O_5, and the reaction mechanism is proposed."

"...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 "

"There are many methods for the determination of chlorine dioxide, including iodometry,'DPD' spectrophotometry, ultraviolet spectrophotometry, and so on. Among them, the iodometry is the most basic, but the iodometry measures all oxides in the sample. The total amount cannot be measured separately."

The micro-coated monobasic chlorine dioxide powder retains the advantages of chlorine dioxide, and is convenient to carry, store and apply, and can kill biological warfare agents, so it has great application potential under field conditions

*******!!!!************ "Chloroperoxidase catalyzes the dismutation of chlorite-forming chloride, chlorine dioxide, chlorate, and oxygen as products. The yields of chlorine dioxide are variable because chloroperoxidase also catalyzes the decomposition of this compound and, in addition, moderate concentrations of chlorine dioxide inactivate the enzyme. Chloride, chlorate, and oxygen are the products of the decomposition of chlorine dioxide. The optimum pH for the enzymic of decomposition of both chlorite and chlorine dioxide is approximately pH 2.75. At this pH, 1 mole of chlorine dioxide is dismutated to 0.3 mole of chloride, 0.7 mol of chlorate, and 0.17 mole of oxygen. At the same pH, the complete decomposition of 1 mole of chlorite yields 0.4 mole of chloride, 0.6 mole of chlorate, and 0.13 mole of oxygen. During the inactivation of chloroperoxidase by chlorine dioxide, the Soret absorption band of the native enzyme is completely lost, and the enzyme becomes chlorinated. Kinetic parameters for the chlorite reaction have been determined. The Km value for chlorite obtained from various kinetic plots was about 10 mM. The catalytic rate constant for the formation of chlorine dioxide from chlorite was about 70,000 s-1."

2005 "The reactions of aqueous ClO2 with tyrosine, N-acetyltyrosine, and dopa (3,4-dihydroxyphenylalanine) are investigated from pH 4 to 7. The reaction rates increase greatly with pH to give a series of oxidized products."

"The heme enzyme chlorite dismutase (Cld) catalyzes the degradation of chlorite to chloride and dioxygen. Although structure and steady-state kinetics of Clds have been elucidated, many questions remain (e.g., the mechanism of chlorite cleavage and the pH dependence of the reaction). "

{Includes formulas for calculations}

Acanthamoeba castellanii is a free-living amoebae commonly found in water systems. Free-living amoebae might be pathogenic but are also known to bear phagocytosis-resistant bacteria, protecting these bacteria from water treatments. The mode of action ...

The U.S. Department of Energy's Office of Scientific and Technical Information

"To solve the problem of shortened backwashing intervals in groundwater plants, several disinfectants including ozone (O3), hydrogen peroxide (H2O2) and chlorine dioxide (ClO2) were examined to peel off the film from the quartz sand surface in four pilot-scale columns."

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)"

"we assessed the associated genotypic and phenotypic traits. ClO2 resistance emerged after E11 populations were repeatedly reduced (either by ClO2-exposure or by dilution) and then regrown in cell culture. The resistance was linked to an improved capacity of E11 to bind to its host cells, which was further attributed to two potential causes: first, the resistant E11 populations possessed mutations that caused amino acid substitutions from ClO2-labile to ClO2-stable residues in the viral proteins, which likely increased the chemical stability of the capsid toward ClO2. Second, resistant E11 mutants exhibited the capacity to utilize alternative cell receptors for host binding. Interestingly, the emergence of ClO2 resistance resulted in an enhanced replicative fitness compared to the less resistant starting population."

Previous studies showed that temperature and total organic carbon in drinking water would cause chlorine dioxide (ClO(2)) loss in a water distribution system and affect the efficiency of ClO(2) for Legionella control. However, among the various causes of ClO(2) loss in a drinking water distribution …

Chlorine dioxide (ClO2) decay in the presence of typical metal oxides occurring in distribution systems was investigated. Metal oxides generally enhanced ClO2 decay in a second-order process via three pathways: (1) catalytic disproportionation with equimolar formation of chlorite and chlorate, (2) reaction to chlorite and oxygen, and (3) oxidation of a metal in a reduced form (e.g., cuprous oxide) to a higher oxidation state. Cupric oxide (CuO) and nickel oxide (NiO) showed significantly stronger abilities than goethite (α-FeOOH) to catalyze the ClO2 disproportionation (pathway 1), which pr...