Sciencemadness Discussion Board

Ozone related questions

plante1999 - 14-6-2011 at 08:10

Today I made my first O3 generator using sulfuric acid electrolisis, this type of generation produce a mix of H2, O2 and O3. the cell was efficient , but it was very dangerous ( 2 time the stopper exploded because the curent was not going to the cell , so the ozone decompose with heat , and this make the hydrogen explode) , the cell was en 150 ml erlenmeyer with 100ml of 15% of H2SO4 by weight Lead anode and carbon cathode , so the 50ml of gas explosion was so loud that i can ear it 100m away when i was in my house (i live in campaign so this isn a problem) , so i dessided to make a more safe one (take note that the first cell was buryed 30 cm in sand) but i have some question for the next cell i will made.


1: how can i get rid of the hydrogen at 20-50 degree celcius (i do not want to destroy the ozone that i form) with a processe/chemical that it cheap to run week ore months.

2: I have read this equation:
2NaX + O3 + H2O -) O2 + 2NaOH + X2
X=halogen
and i want to know :
1: If this reaction work or it require catalist.
2 If this two competiting reaction can happen at 30-50 ( the temp of cooling water that i will use to cool the cell):

2NaOH + X2 -) NaX + NaOX + H2O
3NaOX -) NaXO3 + 2NaX

Overall reaction ( water as a catalist):
NaX + 3O3 -) NaXO3 + 3O2

X=halogen

I am thinking of a new way to produce bromate....

3: How can i make i test for 0.1-1% of bromine in water?


Take note that the process that i think is generating ozone and passing it trough hot NaBr sol.

Thanks!!


[Edited on 14-6-2011 by plante1999]

[Edited on 14-6-2011 by plante1999]

[Edited on 14-6-2011 by plante1999]

hissingnoise - 14-6-2011 at 08:47

Quote:
Today I made my first O3 generator using sulfuric acid electrolisis, this type of generation produce a mix of H2, O2 and O3. the cell was efficient , but it was very dangerous

What arrangement have you in place to stop hydrogen mixing with the other gasses?

hyperkinetic - 14-6-2011 at 09:13

You could feed separated O2 from a Hoffman style apparatus into a chamber and ether hit it with strong UV or use a flyback to ionize it and produce O3/O2.

m1tanker78 - 14-6-2011 at 09:38

@Plante: Are you following a specific paper/procedure? I have two O3 generators and have been wanting to try an ozonolysis or similar procedure. If your procedure isn't terribly complicated or glassware-hungry, I can probably try it out and report back.

Tank

plante1999 - 14-6-2011 at 10:36

Quote: Originally posted by hissingnoise  
Quote:
Today I made my first O3 generator using sulfuric acid electrolisis, this type of generation produce a mix of H2, O2 and O3. the cell was efficient , but it was very dangerous

What arrangement have you in place to stop hydrogen mixing with the other gasses?


the hydrogen is mixed with the O3 and O2 gas, it is why i need to know how to separ it chemicaly... If anyone can try to make bromate from O3 and NaBr/and make a report of the synthesis , it will be greatly appreciated.

hyperkinetic - 14-6-2011 at 11:05

Just keep it separated from the start.


Do you have two electrodes stuck into a flask? If you provide a physical barrier you can prevent the hydrogen from mixing in with the oxygen products. I think this is what Hissingnoise was moving towards.

I assume you are familiar with a Hoffman apparatus. If you isolate the gas being evolved from a single electrode by setting it in a glass tube you will not have the explosive H2/Ox mixture. Just pipe the hydrogen off.

You could let the hydrogen settle out of the mixture if you could keep stable for long enough but that seems to be a harder way of doing it.

hissingnoise - 15-6-2011 at 04:43

A cell, partitioned to prevent mixing is essential because H<sub>2</sub>/O<sub>2</sub> is easily ignited by spark or flame.
The electrodes in a voltameter are spaced too far apart for efficiency . . .


symboom - 30-6-2017 at 08:35

There is a process where ozone can be made from electrolysis of sulfuric acid and also a youtube video showing it

[Edited on 30-6-2017 by symboom]

MeshPL - 30-6-2017 at 10:08

I would say it is nigh impossible. Just separate the cell.

Melgar - 30-6-2017 at 19:07

Yeah, even a really porous physical barrier, like a piece of cloth glued to the sides, is better than nothing. Two flasks connected via a siphon filled with solution (and possibly some unrolled cottonballs) could even work. Hydrogen is lighter than air and even helium, so if hydrogen is able to escape to the atmosphere, it will very quickly reach levels where it isn't a problem.

symboom - 30-6-2017 at 23:15

Here is the video the only one I can find that does not use corona discharge methode to produce ozone
https://m.youtube.com/watch?v=Jrd_qQWl8b0
It uses sulfuric acid with lead and carbon electrodes
Lead for the anode

AJKOER - 2-7-2017 at 09:29

Here is an extract explaining possible reaction pathways with ozone, to quote:

"Ozone can attack as a dipole, molecule, electrophilicly or as a nucleophilic agent. Ozone reacts in water, or any aqueous solution, in two ways: DIRECTLY as molecular ozone via three mechanisms; (slow and very selective), forming aldehydes, ketones and carboxylic acids, cyclo addition (+ & -); on unsaturated bonds, as a dipole. ozonide > carbonyl > hydroxy-hydro peroxide > carbonyl & hydrogen peroxide electrophilic (+); on molecular sites with strong electronic density. aromatics (phenol & aniline) nucleophilic (-); on molecular sites with an electronic deficit, usually on carbons carrying electron withdrawing groups. INDIRECTLY via radicals formed as it decomposes in water; A few such radicals are as follows; hydroxyl radical, .OH , a main reactive ingredient hydroperoxide radical, .HO2 superoxide radical ion, .O2-, ozonide radical ion, .O3- The indirect reactions produced by molecular ozone are limited only by the various radicals it produces, which varies with the initial water quality. The worse the water quality problems are, the more ozone can potentially rise to the occasion.

Even with the ozone used up quicky, the radicals it forms will continue reacting. One indirect example of ozone molecules contacting water (O3 + H2O = O2 + .OH + .OH)..."

Source: " OZONE { O3} IN DRINKING WATER TREATMENT a brief overview..", link: https://www.google.com/url?sa=t&source=web&rct=j&...

Technically, the last reaction is not accurate as are some comments in the article (like the hydroxyl ion is a water cleaning agent, it is primarily the hydroxyl radical, but OH- does serve an initiating role, see equations below). My technical assertion on the corrected reaction is as follows:

O3 + hv --> O2 + O
O + H2O = .OH + .OH (Source: see https://books.google.com/books?id=HZ2wNtDOU0oC&pg=PA163&... )

So, the net reaction of ozone with H20 in the necessary presence of UV light is:

O3 + H2O + hv --> O2 + .OH + .OH

Note, hydroxyl radicals can be created by the action of water on ozone, but the reaction is pH dependent, and is not given by the above equation.

In fact, in water with a pH above 7, the reaction can proceed as follows:

O3 + OH- --> .O2- + .HO2
.HO2 = H+ + .O2-
.O2- + O3 --> O2 + .O3-
.O3- + H+ = .HO3
.HO3 --> .OH + O2

Source: See, for example, "Ozonation of Tris-2-Chloroethyl Phosphate (TCEP) in Water" by Michael J. Votruba, link: https://www.google.com/url?sa=t&source=web&rct=j&...

The above approximately (as there are more possible reactions) implies a net reaction in alkaline water of:

2 O3 + OH- --> .O2- + .OH + 2 O2 (pH cited as 8.5 or higher in applications)

but, in actuality, an intermediate reaction, as the products can further react with themselves (and subsequent products) and also with more ozone.

Note, in atmospheric chemistry, where we are working with aerosols, due to a change in the dielectric constant for the medium (which impacts pKa, see https://en.m.wikipedia.org/wiki/Hydroperoxyl), the superoxide is found mostly in the form of .HO2. The implied approximate net reaction would then be:

2 O3 + H2O --> HO2 + .OH + 2 O2

[Edited on 3-7-2017 by AJKOER]