Sciencemadness Discussion Board

SO3 from Photolysis of SO2 with Cl2 and O2

AJKOER - 28-12-2021 at 09:02

I plan on trying out (awaiting my source for SO2) to affirm, at least, a theoretical creation of SO3 from the photolysis of SO2 with Cl2 and O2.

The chemistry is all present here "Application of Gaseous ClO2 on Disinfection and Air Pollution Control: A Mini Review" https://aaqr.org/articles/aaqr-20-06-covid-0330.pdf with the exception of the photolysis of chlorine gas:

Cl2 + UV → •Cl + •Cl (see https://pubs.acs.org/doi/pdf/10.1021/ja01408a010 )

Cl2 + H2O = HOCl + HCl

H2O + •Cl → HCl + •OH 1.17 × 10^8 -- (Bryukov et al., 2006)

SO2 + HOCl → SO3 + HCl -- (Kaczur, 1996)

SO2 + •OH → •HOSO2 7.89 × 10^8 -- (Atkinson et al., 2004)

•HOSO2 + O2 → H2O + SO3 7.89 × 10^8 -- (Atkinson et al., 2004)

Actually, the above reaction is more correctly presented as

•HSO3 + O2 -> SO3 + H+ + •O2- (See Eq (10) here https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7558052/ )

And possibly also, not necessary but beneficial, reactions including:

HOCl + UV → •OH + •Cl (see https://pubmed.ncbi.nlm.nih.gov/29279579/)

HOCl + •OH → •ClO + H2O (see https://pubs.acs.org/doi/10.1021/ja100976b )

And relatedly:
-OCl + •OH → •ClO + OH-

HOCl + •O2- → •OH + Cl- + O2 (see https://ar.iiarjournals.org/content/33/9/3589#:~:text=The%20... )

Cl2O (as escaping from HOCl) +UV → •Cl + •ClO (see https://royalsocietypublishing.org/doi/10.1098/rspa.1971.011... )

•ClO + •ClO → •ClO2 + •Cl 2.11 × 10^8 -- (Atkinson et al., 2007)

4 SO2 + 2 •ClO2 → 4 SO3 + Cl2 - - (Kaczur, 1996)

The experiment is intended to consist of a solution of HOCl/NaOCl that is sitting at the bottom of a vessel that has been filled with O2, SO2 and Cl2 (from the prior action of adding a small amount of H2O2/NaHSO4/Na2S2O5 into the aqueous NaOCl). The vessel is made of material allowing UV/strong sunlight photolysis and further permitting recovery of any deposited SO3 from the surface of the vessel.

The favorable aspects of this reaction system is that water vapor H2O (which could convert SO3 to H2SO4) is effectively replaced with HCl which can, with HOCl, lead to more Cl2 which under light treatment restarts the reaction cycle above.

The reaction system is complex so comments on potential issues would be appreciated.

[Edited on 28-12-2021 by AJKOER]

Ubya - 28-12-2021 at 10:30

HOSO2 + O2 → H2O + SO3 7.89 × 10^8 -- (Atkinson et al., 2004)

What's stopping SO3 from reacting with water to form sulphuric acid?

SO3 will react with any water present.
This also applies to the acqueous solution of HOCl/NaClO

AJKOER - 28-12-2021 at 11:02

Ubya:

Thanks, a very important point. The SO3 is expected to be recovered as part of a gas phase reaction with electrostatic condensing on the dome/vessel. By the way, I have corrected said cited reaction as incorrect with a 2020 source reference presented below it where •HSO3 is •HOSO2. Note, now there is no water formation. Clearly, Atkinson presented an approximation as the equation is not balanced and the expected products starting with a single radical entity should produce a radical entity (also missing). The revised 2020 referenced equation, at least, meets these standards, although I prefer •HOSO2 to •HSO3.

More generally, on the water issue, for example, per a prior discussion on SM, I alluded to the claimed action of SO2 passed over HNO2 whose vapors provide a source of •NO2 stable free radical. Here is the link http://www.sciencemadness.org/talk/viewthread.php?tid=85001#... and the citation:

"Here is a quote from Atomistry.com on HNO2 acting on SO2 to quote:

"Stannous chloride is converted into stannic chloride, sulphuretted hydrogen into sulphur, sulphur dioxide into sulphur trioxide. Iodine is liberated from potassium iodide" "

Note, the cited opening reference also claims a reaction based on the •NO2 radical as suggestively could be sourced from HNO2 per above (where I now propose a photolysis induced chlorine family of radicals in place of •NO2):

2 SO2 + •NO2 → SO3 + •NO 6.31 × 10^9 (Armitage and Cullis, 1971)

So, the quantity of water vapor exposure is critical.

As such, my proposed experimental design may still indeed allow too much water exposure, one solution is to use aqueous NaOCl to prepare a solid dibasic magnesium hypochlorite solid (see my work here http://www.sciencemadness.org/talk/viewthread.php?tid=26741#... ) and work with a moist thin layer of this salt in the reaction chamber.

I may also investigate a method of passing over vapors as was cited above as actually allowing apparent SO3 formation (where the movement of gas may favor electrostatic charge accumulation and surface deposition of SO3 as a particle suspension in air).

Or, try keeping the current design and add a select amount of a drying agent (like CaCl2) and induce an electrostatic charge at the top of the vessel (perhaps rubbing with fur, or suspending in the vessel a glass rode that was rubbed with fur, thereby introducing a triboelectric effect, see discussion here https://en.wikipedia.org/wiki/Triboelectric_effect).

Goal is to maintain a simple design, as I view favorably the implied theoretical chemistry discussed so far for the reaction system.

[Edited on 28-12-2021 by AJKOER]

Ubya - 28-12-2021 at 20:57

https://youtu.be/x5YFK8mmeRQ
Electrostatic precipitators are pretty easy to make, i bet the fur won't be enough

AJKOER - 29-12-2021 at 07:21

Thanks Ubya,

Quite interesting video.

However, do not dismiss the power of elecrostatic discharge (ESD).

There was an occasion when combination of clothing I was wearing and my companion (upon walking together) was not apparently compatible. Normally, ESD is just a liitle annoyiing, but on that occasion, it was frequent and actually painful!

An unintended and unwanted science experiment in ESD.

[Edited on 29-12-2021 by AJKOER]

Ubya - 29-12-2021 at 19:24

Quote: Originally posted by AJKOER  
Thanks Ubya,

Quite interesting video.

However, do not dismiss the power of elecrostatic discharge (ESD).

There was an occasion when combination of clothing I was wearing and my companion (upon walking together) was not apparently compatible. Normally, ESD is just a liitle annoyiing, but on that occasion, it was frequent and actually painful!

An unintended and unwanted science experiment in ESD.

[Edited on 29-12-2021 by AJKOER]


Oh i know, a few years ago i had a plastic jacket, my ex girlfriend was really fond of wool sweaters, and that combination caused many, too many "sparky" kisses.
Even if we aren't together anymore in winter we have the fear of hugging because of those memories lol