Chemical & Biological Dynamics

"[Is this statement accurate?] AOX, or chlorinated organic compounds, are formed when chlorine dioxide reacts with residual lignin during pulp bleaching." "Today’s mills use chlorine dioxide is used instead and its use minimised with oxygen and peroxide stages. Thus AOX emissions have declined significantly and current AOX levels have been determined to have no effect on toxicity of the effluent."

Read chapter The Pulp and Paper Industry: This volume provides insights into the environmental practices of five industry sectors: materials processing, m...

Cooling systems offer an ideal environment for microbiological fouling. Take steps now to look for and treat scaling and fouling.

{Includes useful comparison charts of characteristics}

(2003) "Chlorine dioxide is a moderately strong oxidant. It does not chlorinate or alkylate chemical species, but oxidizes them. The residue after treatment of waste includes only chloride ion, plus the oxidation products from the treated material. "

****!!!! (2017) "This is the first aerobic oxidation of methane without using high temperature/pressure, and the concept could allow industry-scale reactions with reduced environmental impact." "This doesn't occur in water, but unfortunately methane barely dissolves in water." The researchers found a neat way around this: two solvents in a single system, one for each step of the process. The initial ClO2• formation occurs in a water phase, where sodium chlorite is soluble. Then, ClO2• transfers to a perfluorohexane (PFH) phase, where methane and O2 dissolve to react with them. "PFH is ideal for the second step: it dissolves methane, but doesn't react with CH3• radicals," explains Ohkubo. "This creates a space for the oxidation of CH3•, giving the desired products. Then, after methanol and formic acid are formed, they cross the solvent boundary in the opposite direction, into the water phase. Here they are protected against further oxidation into unwanted CO or CO2 as greenhouse gasses." The complete process is impressively efficient, converting over 99% of methane into the target products, without the need for high temperature or pressure. "This is the first successful use of oxygen in the air to oxidize methane under ambient conditions,"

"Oxidation of hydrocarbons: The chlorine dioxide radical (ClO2.) was found to act as an efficient oxidizing agent in the aerobic oxygenation of methane to methanol and formic acid under photoirradiati...

The reactivities of the chlorine dioxide (ClO2), which is a stable free radical towards some watersoluble spin-traps were investigated in aqueous solu…

"for the selective oxidants, the competition disappears rapidly after the ERMs present in EfOM are consumed. In contrast, for hydroxyl radicals, the competition remains practically the same during the entire oxidation. Therefore, for a given oxidant dose, the selective oxidants were more efficient than hydroxyl radicals for transforming ERMs-containing micropollutants, while hydroxyl radicals are capable of transforming micropollutants even without ERMs"

"The results show that dimethyl trisulfide and isoprene were substantially degraded into other by-products, including methane sulfonyl chloride and sulfur dioxide, during oxidation by chlorine dioxide and ozone, respectively. In contrast, 1-bromopropane, 2,3-butanedione and 1,1,2-trichloroethane have slow reaction kinetics and did not break down completely. Degradation of dimethyl trisulfide by chlorine dioxide and ozone follows the second order kinetics with half-lives of 2.2 min and 24 min, respectively. On the other hand, isoprene follows the first order reaction kinetics with rate constants of 0.4051 min-1 and 0.02244 min-1 and half-lives of 1.73 min and 32 min for degradation using ozone and chlorine dioxide, respectively. iv The oxidative degradation of 1-bromopropane, dimethyl trisulfide, and 2,3-butanedione by chlorine dioxide were more efficient than their reactions with ozone. However, the degradation of isoprene and 1,1,2-trichloroethane showed a greater reactivity toward ozone compared to chlorine dioxide. Most of the reaction products of oxidative degradation such as acetone, ethanol, formic acid, and dimethyl ether are chemically benign. But there are also by-products such as methane sulfonyl chloride, sulfur dioxide, chloroform, and cyanogen bromide that require further toxicological study."

"Tiberian Technologies' Process & Equipment Division in March 1999 undertook pilot studies to model the performance of the patented SVP-Pure chlorine dioxide scrubber technology" "Eka's process generates chlorine dioxide gas from a mixture of sodium chlorate, hydrogen peroxide, and sulfuric acid. The process is rapid and better than 95% efficient" " using the SVP-Pure process versus the compliance test results (using the previous chlorite-based process) produced an average reduction of 52% in VOC emissions." "the sodium chlorate and hydrogen peroxide are available pre-blended as Purate to minimize the bulk storage needs"

****!!!! When a water tap is opened, small amounts of chlorine dioxide diffuse into the air and combine with existing household odors. All homes have volatile organic compounds (VOCs) in the ambient air produced by scented products (soaps, candles, air fresheners, incense, potpourri), cleaning agents or solvents, paint, carpet, furnishings, fresh flowers or wreaths, and many other common household items. The VOC/chlorine dioxide combination odors have been described as smelling like fuel oil, kerosene, chemicals or cat urine, to name the most common. Studies have not identified any health concerns associated with this combined odor. The strongest odors are associated with installing new carpet, upholstered furniture or draperies andinterior painting. The odor will continue until the level of VOCs decreases (new smell goes away). This can take from a few weeks up to several months to dissipate depending on the situation, type of materials, amount of ventilation, etc.

The microwave spectrum of chlorine dioxide has been investigated and several rotational transitions assigned. The resulting rotational constants (in Mc) are: ${\mathrm{Cl}}^{35}$${\mathrm{O}}_{2}$: $A=52072$, $B=9952$, $C=8332$; ${\mathrm{Cl}}^{37}$${\mathrm{O}}_{2}$: $A=50725$, $B=9952$, $C=8295$. These constants are limited in precision by the presence of hyperfine structure which has been only approximately treated. The structural parameters of chlorine dioxide as obtained from the rotational constants are ${r}_{C\mathrm{l}\ensuremath{-}\mathrm{O}}=1.473\ifmmode\pm\else\textpm\fi{}0.01$ A; = 117\ifmmode^\circ\else\textdegree\fi{}36\ensuremath{'}\ifmmode\pm\else\textpm\fi{}1\ifmmode^\circ\else\textdegree\fi{}. Approximate hyperfine constants are given.

****!!!!**** "Waterborne viruses" "we assessed the associated genotypic and phenotypic traits... 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. "

Reactions of tryptophan, N-methyltryptophan and 3-indolelactic acid with aqueous chlorine or chlorine dioxide (ClO2) in 0.1M potassium phosphate buffer, pH 6.0, were investigated to determine any str...

Nonvolatile products generated from reactions of graded molar ratios of aqueous chlorine or chlorine dioxide with L-tryptophan (1:1, 3:1 and 7:1) were shown to be direct-acting mutagens to Salmonella...

****!!!!****!!!!**** {Includes data table of studies of gas and liquid against specific pathogens on food} "ClO2 disinfects by oxidation through the one-electron transfer mechanism, resulting in a reduction to ClO2–...The inactivation may be reached by allowing permeability of the cell membrane by changing the configuration of lipids and protein which involve the oxidation of amino acids by the gas. The second option is due to the reaction with nucleic acid and/or protein structures... However, some research showed degradation in viral RNA, inducing genotoxicity or discontinuing replication of genome information." "At higher relative humidity, a greater reduction of pathogen population was reported. This might be explained due to the increment of the pores’ sizes in the bacteria due to swelling at high humidity, which allow penetration of the ClO2 molecule into the bacteria." "Gaseous ClO2 showed a negative impact on treated fruits and vegetables through enzymatic browning formation... is related to the deterioration of nutritional quality. However, additional treatments can be added to the gas exposure to inhibit browning..." "negative color change in spinach leaves, which occurred during storage after being exposed even to 50 ppm of gaseous ClO2. Also, treatments with higher concentrations may lead to bleaching of fruits and vegetables" "reaction rate was estimated to be... which is significantly higher than the reaction rate reported by previous researchers ... the chamber used here was stainless steel... likely increased the reaction with the walls, and created minor corrosion" "larger exposure surface area for the water in contact with the gas increased the overall decay rate" "some crevices in equipment could impact the effectiveness of the ClO2 gas treatment due to the time for gas to diffuse into the crevice" "the ClO2 gas concentration is surface area- and water volume-dependent" "Results showed an increase in the reaction rate due to water presence at different water volume and exposure surface area. After 7 days’ exposure at 3000 ppm of ClO2 gas, none of the selected plastics or elastomers showed a significance difference (p0.05) in the hardness value." "excitation wavelengths of ClO2 are near the ultraviolet and visible light... leads to dissociation into ClO + O or Cl + O2" " Further research can also be extended to determine the rate of ClO2 molecules dissolving into water, and the residuals form."

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 degrees C. The rates of chlorine dioxide decay are first order in both ClO2 and CSH concentrations and increase rapidly as the pH in …

"three types of aerogels (namely, silica, titania, and zirconia composites) were synthesized"

(2012)

"The reaction rates increase greatly with pH to give a series of oxidized products." " The decay of these phenoxyl−ClO2 adducts also is rapid and is base-assisted to form dopaquinone (from tyrosine) and N-acetyldopaquinone (from N-acetyltyrosine) as initial products. The consumption of two ClO2 molecules corresponds to a four-electron oxidation that gives ClO2- in the first step and HOCl in the second step. The reaction between ClO2 and the deprotoned-catechol form of dopa is extremely fast (2.8 × 109 M-1 s-1). Dopa consumes two ClO2 to give dopaquinone and 2ClO2- as products. Above pH 4, dopaquinone cyclizes to give cyclodopa, which in turn is rapidly oxidized to dopachrome. A resolved first-order rate constant of 249 s-1 is evaluated for the cyclization of the basic form of dopaquinone that leads to dopachrome as a product with strong absorption bands at 305 and 485 nm.

{At bottom, includes links to many highly valuable papers}

The sulfate-reducing bacteria and related corrosion can be inhibited by charge-reversal surfactant antibiotic material. "There are many SRB antibiotics used in petroleum exploitation, including quaternary ammonium surfactants, chlorine dioxide"

In this study, black peppercorns and cumin seeds were inoculated with a five-serotype cocktail of Salmonella or its surrogate Enterococcus faecium"

"we found that UV photolysis after ClOsub2/sub disinfection can effectively eliminate both ClO2..."

Photolysis of ClO2 by UVC radiation occurs in several drinking water treatment scenarios (e.g., pre-oxidation by ClO2 with post-UVC disinfection or a multi-barrier disinfection system comprising ClO2 and UVC disinfection in sequence). However, whether micropollutants …

"At a ClO2 dosage of 74 μM (5.0 mg L–1 as ClO2) and a UV fluence at 47.5 mJ cm–2, the UVA365/ClO2 AOP generated a spectrum of reactive species, including chlorine oxide radicals (ClO•), chlorine atoms (Cl•), hydroxyl radicals (HO•), and ozone at a concentration of ∼10–13, ∼10–15, ∼10–14, and ∼10–7 M, respectively. A kinetic model to simulate the reactive species generation in the UVA365/ClO2 AOP was established, validated against the experimental results, and used to predict the pseudo-first-order rate constants and relative contributions of different reactive species to the degradation of 19 micropollutants in the UVA365/ClO2 AOP. Compared to the well-documented UVC254/chlorine AOP, the UVA365/ClO2 AOP produced similar levels of reactive species at similar oxidant dosages but was much less pH-dependent and required much lower energy input, with much lower formation of chloro-organic byproducts and marginal formation of chlorite and chlorate.

Semantic Scholar extracted view of "The multiple roles of chlorite on the concentrations of radicals and ozone and formation of chlorate during UV photolysis of free chlorine." by J. Zhao et al.