Chemical & Biological Dynamics

"Chlorination is a widespread fouling control practice in water intake structures of power plants and desalination plants. Chlorine dioxide is used... "

PDF | Reaction of styrene with chlorine dioxide under various conditions selectively produces 1-phenyl- 2-chloroethanone, with 1-phenyl-2-chloroethanol,... | Find, read and cite all the research you need on ResearchGate

2021

****!!!!!*** 2020. "The potential role of ClO2 in completely inactivating porcine reproductive and respiratory syndrome virus (PRRSV) was demonstrated through the action of degrading the genome and proteins of the virus [4]. This study also confrmed that the expression of inflammatory cytokines induced by this virus can be reduced by ClO2. This is further supported bystudies reporting protein-denaturing activities due to covalent oxidative modifcation of cysteine, tryptophan and tyrosine residues of model proteins (bovine serum albumin and G6PD of Saccharomyces cerevisiae) as the mechanism behind the efficacy of ClO2 against microbes [13,14]. Furthermore, 0.03 ppm of ClO2 has been indicated to prevent aerosol-induced infuenza A virus by denaturing the envelope proteins of the virus [12]. The mechanism of norovirus inactivation by ClO2 is attained through degradation of viral protein, including viral genomic RNA and disruption of viral strucutre [15]. In addition, an observation on ClO2-reduced lysozyme activities showed the potential role of ClO2 in denaturation and degradation of protein "

****!!!!*** {Illustrations, etc at bottom of this page. Also, cited excerpts available at https://www.researchgate.net/publication/6766479_Kinetics_and_Mechanisms_of_Chlorine_Dioxide_and_Chlorite_Oxidations_of_Cysteine_and_Glutathione." "Chlorine dioxide oxidation of cysteine (CSH) is investigated under pseudo-first-order conditions (with excess CSH) in buffered aqueous solutions, p[H+] 2.7−9.5 at 25.0 °C. The rates of chlorine dioxide decay are first order in both ClO2 and CSH concentrations and increase rapidly as the pH increases. The proposed mechanism is an electron transfer from CS- to ClO2 (1.03 × 108 M-1 s-1) with a subsequent rapid reaction of the CS• radical and a second ClO2 to form a cysteinyl−ClO2 adduct (CSOClO). This highly reactive adduct decays via two pathways. In acidic solutions, it hydrolyzes to give CSO2H (sulfinic acid) and HOCl, which in turn rapidly react to form CSO3H (cysteic acid) and Cl-. As the pH increases, the (CSOClO) adduct reacts with CS- by a second pathway to form cystine (CSSC) and chlorite ion (ClO2-). The reaction stoichiometry changes from 6 ClO2:5 CSH at low pH to 2 ClO2:10 CSH at high pH. The ClO2 oxidation of glutathione anion (GS-) is also rapid with a second-order rate constant of 1.40 × 108 M-1 s-1. The reaction of ClO2 with CSSC is 7 orders of magnitude slower than the corresponding reaction with cysteinyl anion (CS-) at pH 6.7. Chlorite ion reacts with CSH; however, at p[H+] 6.7, the observed rate of this reaction is slower than the ClO2/CSH reaction by 6 orders of magnitude. Chlorite ion oxidizes CSH while being reduced to HOCl, which in turn reacts rapidly with CSH to form Cl-. The reaction products are CSSC and CSO3H with a pH-dependent distribution similar to the ClO2/CSH system."

****!!!!!***** Chlorine dioxide (ClO2), an alternative disinfectant to chlorine, has been widely applied in water and wastewater disinfection. This paper aims at presenting an 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 (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.

*** {Excellent info on Chlorine dioxide characteristics} Pros and Cons of Chlorine Dioxide Pros and Cons of Chlorine Dioxide Advantages: ~Effective for bacteria, viruses, fungi, algae, biofilm etc. ~Very fast acting ~Breaks down rapidly ~No AOX formation ~Not pH dependent ~No reaction with ammonia ~Effective at < 1 ppm concentrations Disadvantages: ~Volatile ~On-site generation required ~Complicated methods of generation

Upcoming webinars discussing chlorine dioxide gas decontamination and ultraviolet light disinfection.

*** {Illustration of chemical dynamics with oxidation. May contain some inaccuracies.}

*** {Excellent Powerpoint presentation about chlorine dioxide, building decontamination, etc}

Introductions Walter Weterman – Director of International Sales Rich Hopkins – Hopkins Technical Products Fred Bender – Hopkins Technical Products Greg Cozzi – Hopkins Technical Products Jeff Drappo – Regional Manager PFC Janet Berbach – Director of Corporate Events Ken Gibson – Director of Business Development

{chart with disadvantages of other ClO2 generation methods, and of tech-grade sodium chlorite} "The single precursor eChem Chlorine Dioxide generation process electrolytically converts Sodium Chlorite to Chlorine Dioxide gas in the patented OxiMax CDE cell. This gas is then stripped from the solution in the patented vClone and then dissolved in water to be stored in the Solution Tank at a level of up to 2,000 ppm. Recirculation of solutions optimises efficiency and minimises power consumption to allow outstanding performance from a compact machine. The process is safe, reliable and is controlled by a microprocessor, which continuously monitors the performance of the machine, makes the appropriate decisions and displays the status via the LEDs and on an LCD screen."

{Chart with concentrations of Chlorite and HCl that can be used with some equipment in generating Chlorine Dioxide for specific applications/uses} {Summaries of ClO2 uses in wide variety of industries}

**** {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"

{bleaching}

***** {pKa} "many compounds used for medication are weak acids or bases, and a knowledge of the pKa values, together with the octanol-water partition coefficient, can be used for estimating the extent to which the compound enters the blood stream. Acid dissociation constants are also essential in aquatic chemistry and chemical oceanography, where the acidity of water plays a fundamental role. In living organisms, acid–base homeostasis and enzyme kinetics are dependent on the pKa values of the many acids and bases present in the cell and in the body. In chemistry, a knowledge of pKa values is necessary for the preparation of buffer solutions and is also a prerequisite for a quantitative understanding of the interaction between acids or bases and metal ions to form complexes."

"At or below MFC, ClO2 damages the plasma membranes of C. albicans mainly by permeabilization, rather than by the disruption of their integrity. K+leakage and the concomitant depolarization of the cell membrane are some of the critical events."

****!!!!***!!!!***!!!!** "Spike protein was first mixed with various concentrations of CD... at room temperature for 5 min." "CD at 0.25 mmol/L or 0.5 mmol/L was effective in inactivating the binding of the spike protein to ACE2.. However, CD was not effective at 0.1 mmol/L concentration. The result strongly suggests that CD in sufficient cnocentration is effective in inactivating the spike protein of SARS-CoV-2 coronavirus and thus preventing its binding to human cells."

"The reaction rates increase greatly with pH to give a series of oxidized products."

{Need clarification on why PFA is specified as more widely applicable disinfectant than chlorine dioxide?} "We studied the toxicity of the alternative disinfectants peracetic acid (PAA), performic acid (PFA) and chlorine dioxide (ClO2) and their degradation products hydrogen peroxide (H2O2) and chlorite (ClO2-) on Vibrio fischeri and Daphnia magna. ClO2 was more toxic to D. magna (EC50 < 0.09 mg/L) and PFA was most toxic to V. fischeri (EC50 0.24 mg/L). EC50 of PFA, PAA, ClO2, H2O2 and ClO2- on D. magna were 0.85, 0.78,

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

****!!!!**** "we challenged the hypothesis that ClO2 decreases the viral load and virus-induced mortality in a vertebrate model. For this, we determined viral load, virus-induced lesions and mortality in 10-day old chick embryos" " viral titres were 2.4-fold lower and mortality was reduced by half in infected embryos that were treated with ClO2." " Lesions typical of IBV infections were observed in all inoculated embryos, but severity tended to be significantly lower in ClO2-treated embryos. We found no gross or microscopic evidence of toxicity caused by ClO2 at the doses used herein. Our study shows that ClO2 could be a safe and viable way of treating and mitigating the effects of avian coronavirus infections, and raises the possibility that similar effects could be observed in other organisms." The authors have declared no competing interest.

To maintain the high quality of potable water chlorine based disinfectants are frequently dosed into the drinking water network. Considering the oxidative nature of these species their long-term impact on the aging of polyolefin pipes is a matter of...

**** {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."

****!!!!**** "The inactivation of virus and the inhibition of specific attachment both increased with increasing pH and increasing disinfectant concentration." "Inactivation of f2 was hypothesized to occur as the result of chlorine dioxide reacting with discrete chemical moieties in the viral protein. Cysteine, tyrosine and tryptophan reacted with chlorine dioxide within a time frame that could affect viral inactivation. In denatured f2 capsid protein monomers, these amino acids were almost totally degraded within 2 min by chlorine dioxide. Only tyrosine reacted with chlorine dioxide following treatment of the intact virion with disinfectant. Even though the degradation of tyrosine residues occurred at a much slower rate than the rate of virus inactivation, the protein component of f2 virus appeared to be the site of the lethal lesion produced by chlorine dioxide. These tyrosine reactions with chlorine dioxide appeared to alter the virus such that specific attachment was inhibited."

****!!!!****"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"

2005