Chlorine dioxide calculators

From the chlorine/chlorine dioxide production relationship, 0.53 wt of chlorine produces 1 wt of chlorine dioxide, calculator c4-13. 

In solutions, the concentration of available chlorine in the form of hypochlorite or hypochlorous acid is called free-available chlorine. The available chlorine in the form of undissociated A/-chloro compounds is called combined-available chlorine. Several analytical methods can be used to distinguish between free- and combined-available chlorine (8). Bleaches that do not form hypochlorite in solution like chlorine dioxide and nonchlorine bleaches can be characterized by thek equivalent available chlorine content. This can be calculated from equation 5 by substituting the number of electrons accepted divided by two for the number of active chlorine atoms. It can also be measured by iodomettic titration. 

An equation for calculating the partial pressure of chlorine dioxide above specified chlorine dioxide solutions at various temperatures based on the data from reference 24 has been developed (25) ... 

The vapor pressure of chlorine dioxide, Cl02, is 155 Torr at —22.75°C and 485 Torr at ().()0°C. Calculate (a) the standard enthalpy of vaporization (b) the standard entropy of vaporization (c) the standard Gibbs free energy of vaporization (d) the normal boiling point of C102. 

A bleach solution was being prepared by mixing solid sodium chlorite, oxalic acid, and water, in that order. As soon as water was added, chlorine dioxide was evolved and later exploded. The lower explosive limit of the latter is 10%, and the mixture is photo- and heat-sensitive [1]. It was calculated that the heat of reaction (1.88 kJ/g of dry mixture) would heat the expected products to an adiabatic temperature approaching 1500°C with an 18-fold increase in pressure in a closed vessel [2],... 

Table. Experimental on [1] and calculated values lg(k) for kinetic of propanthiol oxidation by chlorine dioxide...

Only CIO2 is known. Chlorine dioxide is an odd-electron molecule. Theoretical calculations suggest that the odd electron is delocalized throughout the molecule, and this probably accounts for the fact that there is no evidence of dimerization in solution, or even in the liquid or solid phase. Its important Lewis structures are shown below ... 

Recent work on these reactions by Rapson et al. has been summarized . They have measured (spectrophotometrically) initial rates of formation of chlorine dioxide in moderately strong sulphuric acid solutions (to 6 M). The order in total sulphuric acid concentration is found to be 12-13 when the molal activity of sulphuric acid is calculated, the order is 4.4-4.5. The order in chlorate is close... 

Figure 11.19. Correlation between the second-order rate constants for reactions of substituted phenoxide anions with chlorine dioxide and estimated values of AG°. The circles are experimental data and the curves represent fits of the data to the Marcus equation. The solid curve corresponds to equation 46 (X = 30.1 kcal moP ). AG° (and log K) values were calculated from electrode half-wave potentials. (Adapted from Tratnyek and Hoigne, 1994.)...

Elder, T. 1998. Reactions of lignin model compounds with chlorine dioxide molecular orbital calculations. Holzforschung 52(4) 371-384. 

Hypobromous acid (HOBr) and all three bromoamines species (NH2Br, NHBr2, NBra) are analyzed as a sum parameter and hypochlorous add (HCXZl), monochloramine (NH2CI), and chlorine dioxide (CIQ2) can be determined selectively. However, no distinction is possible between HOCl and the active bromine spedes. Free chlorine and NH2CI can be measured in the presence of ozone. The method is therefore suitable if combinations of disinfectants are used, such as chlorine/chlorine dioxide or chlorine/ ozone. In natural waters, the method provides a detection limit for all chlorine/bromine species of less than 0.1 mM. The oxidation reaction with ABTS is fast and has a known stoichiometry therefore, a direct calculation of the analyte concentration using the molar absorptivity of the colored oxidation produd is possible. 

These chlorine radicals are the ozone-removing agents. They react with ozone to form chlorine monoxide radicals and molecular oxygen. The chlorine monoxide radical then reacts with more ozone to form chlorine dioxide, which dissociates to regenerate a chlorine radical. These three steps—two of which each destroy an ozone molecule— are the propagating steps that are repeated over and over. It has been calculated that a single chlorine atom destroys 100,000 ozone molecules ... 

Expressing the weight relationship in this way allows the sodium chlorite consumption to he calculated for any concentration or for any chlorine dioxide production amount. Also, any weight units can he used as long as all the units used are identical. 

This relationship can he further expanded hy substituting the equation for chlorine dioxide feed shown in calculators c4-12 and c4-13. Thus, we have the basic relationship (c4-14) that is useful in calculating the sodium chlorite of any concentration needed to produce a given amount of chlorine dioxide. Remember, these relationships are drawn from the chemical equations, thus 100 percent efficiency is assumed. Lower efficiency therefore results in amounts that differ from these calculated values. However, the calculated values are useful to estimate chemical use, and these can be used to evaluate generator efficiency (see A Generator Purity Calculation, p. 53). 

Example 4-9 Calculate the amount of 25 percent sodium chlorite solution (theoretical) needed to generate 400 Ib/day of chlorine dioxide. How many gallons of 25 percent sodium chlorite solution is this ... 

The chlorine needed to produce a given amount of chlorine dioxide is similarly determined by calculator c4-15. Remember that this is based on the chemical equation that assumes 100 percent efficiency. Generators are not always this efficient, so the chlorine needed may be more than the result of this calculation. However, this calculated value is useful in estimating the amount needed and in determining the generator efficiency. 

These systems generate chlorine dioxide gas so the dosage calculations are the same as pure gas systems (c4-l and c4-2). Chlorine dosage produces chlorine dioxide according to the theoretical relationship above (0.53 wt units of chlorine produce 1 wt unit of chlorine dioxide), but a maximum production concentration of about 8 percent. 

Example 4-11 Calculate the chlorine feed setting for a chlorine dioxide dosage of 0.5 mg/L and a water flow of 0.3 ML/day. 

The concentration of chlorine dioxide in the generator effluent is measured in some systems and is used as a dosage control. This value is calculated from the required chlorine dioxide production (calculators c4-12 and c4-13) and the water flow rate through the generator (for liquid sodium chlorite systems). 

There are several ways to calculate generator yield (efficiency). One calculation method defines yield as the ratio of chlorine dioxide concentration to chlorine dioxide concentration plus concentrations of chlorite and chlorate. Purity is another related calculation that includes excess chlorine in the ratio. The theoretical relationship shown in c4-14 can be used as another possible way of determining this value. The chlorine dioxide value from this relationship assumes 100 percent efficiency of the generator. This amount can be compared to the measured chlorine dioxide concentration and the purity thus determined. 

Chlorine Dioxide Generator Output Concentration Calculators... 

---