Chemical & Biological Dynamics

****!!!!****!!!!**** {ICA TriNova} "method for treating an object with chlorine dioxide gas, comprising contacting the object with chlorine dioxide gas while exposing the object to less than 1000 lux of light. The disclosed method minimizes chlorine containing residue on the surface of the object. The object can be a raw agricultural commodity (RAC) such as a raw fruit or vegetable." "Residues on the walls of each jar were quantitatively recovered by washing the walls sequentially with 4-50 mL aliquots of nanopure water and combining the aliquots with additional water to bring the total volume to 250 mL. These washings were analyzed by ion chromatography for chlorate and perchlorate ions. Based on reaction profiling of these particle mixtures, the weights of the particles provided within the TYVEK sachets were adjusted so that, upon reacting, a total of 1.6 mg of ClO2 would have been produced in each jar during the 2 hour period. " "Gas Chamber Studies Show Chlorate and Perchlorate Ions can be Minimized and in the Case of Perchlorate Eliminated when Fumigation is Performed in the Substantial Absence of Light when RACs are Present" "At 120 minutes, chlorine dioxide concentrations... fell well below expected concentrations, likely due to system leaks or to chlorine dioxide reacting with the exposure chambers themselves or with the silicone sealant used on the tanks. When tomatoes were present in the treatment chambers, chlorine dioxide gas was measurable only through 30 minutes for two replicates and through 60 minutes for one replicate. These data clearly indicate that tomatoes acted as a chlorine dioxide sink, consistent with studies using radiolabel showing the propensity for chlorine dioxide consumption by biologic materials, especially those tissues with a porous surface"

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

****!!!!****!!!!*** (2011) "degradation rate of chlorine dioxide with the same initial mass concentration decreased gradually under uv, sunlight, 254 nm uv and 400-700 nm fluorescence, respectively, and the degradation rate of chlorine dioxide with the same initial mass concentration increased with the increase of gas mass concentration when the temperature varied from 15 to 25°c. therefore, the wavelength that plays a major role in the photodegradation of chlorine dioxide is ultraviolet light near 365 nm; the temperature has little effect on its degradation rate; under sunlight exposure, the degradation rate of chlorine dioxide is proportional to the first square of mass concentration, which belongs to the primary reaction, and its half-life is not related to the initial mass concentration, only related to the reaction rate constant k, and the half-life is about 63 min."

****!!!!****!!!!*** (2015) ***"A methodology is proposed for quantifying the amount of ClO2 gas needed in a package and/or treatment chamber." "The diffusion coefficient was found to be 0.129, 0.145, 0.173 cm2 s−1 at 5, 23, and 40 °C, respectively. Degradation of ClO2 gas under dark, UV-A and fluorescent lamp exposure was found to follow a first-order reaction. Degradation using a 40 W UV-A lamp was approximately four orders of magnitude larger than with a 34 W fluorescent lamp." "ClO2 gas can also be converted to chlorite and then react with oxygen changing their chemical structure, mobility, and properties" "Normally, the antimicrobial activity of gaseous ClO2 increased with a longer treatment time, especially at a low treatment temperature"

The Atlas Accelerated UV testing devices focus on UV specific spectral ranges. They may be used in weathering tests that vary light/dark cycles, temperature, condensing humidity, water sprays, and irradiance control.

"maximum absorbance wavelengths for chlorine dioxide and hypochlorous acid were 360 nm and 292 nm"

"Bio-Cide International... developed 'stabilized chlorine dioxide'"... "thermostability, UV absorption spectrum, specificity of the paper chromatogram, microstructure and ionic chromatogram of this solution were studied, and contrasted with pure NaClO2 and ClO2. The results show that ClO2 in 'stabilized chlorine dioxide' solution exists in the form of chlorite ClO2-, carbonate exists in the form of bicarbonate... NCO3-, its pH being 8.5" "Conclusions stated above prove that in ‘‘stabilized chlorine dioxide’’ solution, ClO2 exists in the pattern of chlorite ClO 2-. So-called ‘‘stabilized chlorine dioxide’’ actually is the mixture of NaClO2 and NaHCO3."

"There appeared to be no effect on the efficacy of the ClO2 under light or dark conditions"

"contacting the object with chlorine dioxide gas while exposing the object to less than 1000 lux of light"

****!!!!**** "The photochemical decomposition is characterized by small quantities of O3+ atoms and of equal amounts of chlorine atoms and molecular oxygen, the latter originating in the reaction: ClOO --- Cl + O2" "The isomer ClOO is formed by the geminate recombination of ClO and O, a process which is twice as important as diffusion of the fragments into the mass of the solution an done which represents 30% of the decomposition of the chlorine dioxide. Under our experimental conditions, the lifetime of the ClOO is less than one microsecond."