Chlorine Oxides and Chlorine Oxygen Acids

Vogt, Helmut; Balej, J.; Bennett, John E.; Wintzer, Peter; Sheikh, Saeed Akbar; Gallone, P.

doi:10.1002/14356007.a06_483

Cited by 33 publications

(45 citation statements)

References 108 publications

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“…It is further seen in Table 2 that the residual bacteria and fungi concentrations following disinfection under natural lighting conditions are invariably lower than those following disinfection under artificial light. This finding is reasonable since ClO 2 decomposes under light irradiation (Obvintseva and Gubanova 2004;Vogt et al 2011), and thus, its disinfection efficiency is reduced. In the summer vacation, the bioaerosol concentrations following disinfection are higher than the background level because the luminance is increased, and hence, the ClO 2 disinfection effect is reduced.…”

Section: Resultsmentioning

confidence: 57%

Disinfection of indoor air microorganisms in stack room of university library using gaseous chlorine dioxide

Hsu

Huang

2015

Environ Monit Assess

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As with all indoor public spaces in Taiwan, the stack rooms in public libraries should meet the air quality guidelines laid down by the Taiwan Environmental Protection Administration. Accordingly, utilizing a university library in Taiwan for experimental purposes, this study investigates the efficiency of gaseous chlorine dioxide (ClO2) as a disinfection agent when applied using three different treatment modes, namely a single-daily disinfection mode (SIM), a twice-daily disinfection mode (TWM), and a triple-daily disinfection mode (TRM). For each treatment mode, the ClO2 is applied using an ultrasonic aerosol device and is performed both under natural lighting conditions and under artificial lighting conditions. The indoor air quality is evaluated before and after each treatment session by measuring the bioaerosol levels of bacteria and fungi. The results show that for all three disinfection modes, the application of ClO2 reduces the indoor bacteria and fungi concentrations to levels lower than those specified by the Taiwan EPA (i.e., bacteria <1500 CFU/m(3), fungi <1000 CFU/m(3)), irrespective of the lighting conditions under which the disinfection process is performed. For each disinfection mode, a better disinfection efficiency is obtained under natural lighting conditions since ClO2 readily decomposes under strong luminance levels. Among the three treatment modes, the disinfection efficiencies of the TWM and TRM modes are very similar under natural lighting conditions and are significantly better than that of the SIM mode. Thus, overall, the results suggest that the TWM treatment protocol represents the most cost-effective and efficient method for meeting the indoor air quality requirements of the Taiwan EPA.

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Section: Resultsmentioning

confidence: 57%

Disinfection of indoor air microorganisms in stack room of university library using gaseous chlorine dioxide

Hsu

Huang

2015

Environ Monit Assess

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“…The electrosynthesis of sodium chlorate is one of the most important industrial processes, especially for the pulp and paper industry [1]. The production of chlorate occurs via the electrolysis of sodium chloride and water (Eq.…”

Section: Introductionmentioning

confidence: 99%

“…Chlorate is further reduced to form chlorine dioxide (Eq. 2), the state-of-the-art bleaching chemical for kraft pulp [1,3].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Investigation of the Hydrogen Evolution Reaction on Electrodeposited Films of Cr(OH)3 and Cr2O3 in Mild Alkaline Solutions

et al. 2017

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The hydrogen evolution reaction (HER) from water reduction is the main cathodic reaction in the sodium chlorate process. The reaction typically takes place on electrodes covered with a Cr(III) oxide-like film formed in situ by reduction of sodium dichromate in order to avoid reduction of hypochlorite and thereby increase the selectivity for the HER. However, the chemical structure of the Cr(III) oxide-like film is still under debate. In the present work, the kinetics of the HER were studied using titanium electrodes covered with electrodeposited Cr(OH) 3 or Cr 2 O 3 , which were characterized by means of scanning electron microscopy (SEM), energydispersive x-ray spectroscopy (EDX), x-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. A clear difference in the morphology of the deposited surfaces was obtained, and the structure could be revealed with Raman spectroscopy. The kinetics for the HER were investigated using potentiodynamic and potentiostatic techniques. The results show that the first electron transfer is rate limiting and that the activity decreases in the order Cr 2 O 3 @Ti > bare Ti > Cr(OH) 3 @Ti. The low activity obtained for Cr(OH) 3 @Ti is discussed in terms of the involvement of structural water in the HER and the slow ligand exchange rate for water in Cr(III) complexes, while the high activity obtained for Cr 2 O 3 @Ti is rationalized by a surface area effect in combination with reduction of surface water and water in solution.

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“…An average cell voltage of 2.8 V was found in this work, as well as an anodic current efficiency of 96%. The current running through the industrial cells was set to 70 kA, which is significant for the industrial cells of AkzoNobel, Atochem, Chemetics, and Krebs [57]. The figures quantifying the power consumption in one cell gap during 200 h of steady state operation, a start-up with a strongly performing cathode and a start-up with poorly performing cathode are seen in Table 3.…”

Section: Power Consumptionmentioning

confidence: 99%

Current efficiency of individual electrodes in the sodium chlorate process: a pilot plant study

et al. 2017

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Current efficiency in the sodium chlorate process is a key issue in the evaluation of the power consumption. A pilot cell unit for executing the sodium chlorate process was constructed to study the current efficiency of the anode and cathode separately. The effects of sodium dichromate and sodium sulphate concentrations and the electrolyte temperature on the anode and cathode current efficiencies were studied. Corrosion products formed on the mild steel cathodes after their removal from the cell were characterised using X-ray diffraction and infrared spectroscopy. The results show that the cathodic current efficiency increases with increasing dichromate concentrations in the electrolyte until approximately 5 g dm -3 is reached. At this optimum concentration of dichromate, the presence of sulphate ions decreases the cathodic current efficiency. For moderate increases in temperature, the cathodic current efficiency increases, but oxygen evolution is promoted, and the power consumption also increases. Surface characterisation of the electrodes after their exposure to air shows two primary types of behaviour, depending on the process parameters. At low dichromate concentrations, amorphous corrosion layers are formed, while at higher concentrations, reduced forms of iron hydroxides, i.e., ''green rust'', are identified. Although the electrodes were positioned at the open circuit potential for 40 min before their removal from the cell, chromium remains on the cathode surface. This result might explain the corrosion-inhibiting effect of the addition of chromate to the electrolyte. The results from this study can be used to optimise operating procedures in real plants, decrease the energy consumption and minimise the environmental impact of these processes.Electronic supplementary material The online version of this article

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Chlorine Oxides and Chlorine Oxygen Acids

Cited by 33 publications

References 108 publications

Disinfection of indoor air microorganisms in stack room of university library using gaseous chlorine dioxide

Disinfection of indoor air microorganisms in stack room of university library using gaseous chlorine dioxide

Electrochemical Investigation of the Hydrogen Evolution Reaction on Electrodeposited Films of Cr(OH)3 and Cr2O3 in Mild Alkaline Solutions

Current efficiency of individual electrodes in the sodium chlorate process: a pilot plant study

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