ClO2 generation in chambers

From 5-17-15.

Checked the ppm of Cl that was generated inside the modified anaerobic chambers using a total weight of 100 mg of ClO2 reagent. Hours 3.5 to 6.0 were checked and will be added to what was previously discovered.

Time	ppm Cl
0.5 hr	65
1.0 hr	75
1.5 hr	90
2.0 hr	100
2.5 hr	105
3.0 hr	105
3.5 hr	100
4.0 hr	100
4.5 hr	95
5.0 hr	95
5.5 hr	90
6.0 hr	80

As was predicted, based on the previous results, chlorine present in the air inside the chambers peaks and then drops off over the six hours. The peak appears to be around 2.5 - 3.0 hours. The peak ppm of Cl was about 105 and the presence of ClO2 gas inside the chamber is about 0.25 of that (0.25 is about the conversion factor that was determined by David S.). The presence of ClO2 inside the chambers is incredibly low, which it is even more surprising that the spore killing rate is so high. 

Below are the calculations received from the USDA regarding ClO2 gas generation inside the modified anaerobic chambers: 

Assumptions:

Chlorine Dioxide	67.45 g/mol
Temperature	25 C (298.15 K)
Pressure	1 Atm
Total Volume	2.5 Liter
Release Media	10 mg ClO2 per 6 hours at 1 g each of Part A and Part B

Target Concentration	Total Mass ClO2		Concentration ClO2	Mass of Media Part A             Part B
μg/L	μg	mg	ppmv	mg	mg
10	25	0.025	3.6	2.5	2.5
50	125	0.125	18.1	12.5	12.5
100	250	0.250	36.3	25.0	25.0
200	500	0.500	72.5	50.0	50.0
250	625	0.625	90.7	62.5	62.5
500	1250	1.25	181.4	125	125
1000	2500	2.5	362.7	250	250
2000	5000	5.0	725.4	500	500
4000	10000	10.0	1450.9	1000	1000
5000	12500	12.5	1813.6	1250	1250

According to our initial predictions, with a total dry weight of 100 mg ClO2 reagents, we expected to see a ClO2 ppmv of 72.5 (note: not ppm of Cl). The amount of ClO2 we're actually generating inside the chambers is way lower than that (<20 ppmv). The reduced concentration is probably attributed to the polystyrene containers that are used along with the presence of the glass slides lining the bottom. These types of materials all serve as sinks for the gas and the above calculations depict the unrealistic ideal conditions.

//EWW