[wuhtzu]

Laboratory production
Hey

A friend of mine is doing a highschool project about purifying water using ozone (O₃) - so he has to bubble / pump ozone through some water containing microorganisms. The problem is that it seems close to impossible to obtain / buy a ozone canister (at least in Denmark).

So I told my friend he could make the ozone him self through electrolysis. These should be the reactions taking place if you do electrolysis on sulfuric acid with #1 and #3 as competing reactions:

#1: 3 H₂O → O₃ + 6 H⁺ + 6 e⁻; ΔE_o = −1.53 V;
#2: 6 H⁺ + 6 e⁻ → 3 H₂; ΔE_o = 0 V;
#3: 2 H₂O → O₂ + 4 H⁺ + 4 e⁻; ΔE_o = −1.23 V;

This wikipedia article http://en.wikipedia.org/wiki/Ozone#Laboratory_production, and others I've red, suggests a graphite cathode and a platinum anode for this electrolysis. The problem is he has no platinum metal at his disposal.

So my question is this: Can he use another electrode (anode) for this electrolysis?

Of course I'm also interested in hearing your thoughts about this whole idea - is it doable (practically) or would you suggest some other method?

Best regards
Wuhtzu

[Arkcon]

Well, as you can tell from the rest of the article, ozone reacts with many things at room temp, so you will need a platinum anode, or you will lose what little you make.  As I understand it, small municipalities purify their water with ozone, it's cheaper to make onsite than to store chlorine, if the treatment facility is small.  I don't know how well that applies to Denmark, but you might try asking around a little bit more.

[wuhtzu]

So the platinum anode is chosen because it will not react with the created ozone?

...
 I don't know how well that applies to Denmark, but you might try asking around a little bit more.

What do you mean? Ask some more places / do more research about purchase of ozone?

[Arkcon]

I'm thinking you may be able to purchase a cheap generator or tank of ozone from a small municipality, yes.  If your application is big enough, and the municipality is small enough, a university may partial underwrite the cost involved, maybe ...

[dlzc]

Laboratory production
Hey

A friend of mine is doing a highschool project about purifying water using ozone (O₃) - so he has to bubble / pump ozone through some water containing microorganisms. The problem is that it seems close to impossible to obtain / buy a ozone canister (at least in Denmark).

So I told my friend he could make the ozone him self through electrolysis. These should be the reactions taking place if you do electrolysis on sulfuric acid with #1 and #3 as competing reactions:

#1: 3 H₂O → O₃ + 6 H⁺ + 6 e⁻; ΔE_o = −1.53 V;
#2: 6 H⁺ + 6 e⁻ → 3 H₂; ΔE_o = 0 V;
#3: 2 H₂O → O₂ + 4 H⁺ + 4 e⁻; ΔE_o = −1.23 V;

This wikipedia article http://en.wikipedia.org/wiki/Ozone#Laboratory_production, and others I've red, suggests a graphite cathode and a platinum anode for this electrolysis. The problem is he has no platinum metal at his disposal.

So my question is this: Can he use another electrode (anode) for this electrolysis?

Of course I'm also interested in hearing your thoughts about this whole idea - is it doable (practically) or would you suggest some other method?

Best regards
Wuhtzu

Ozone cannot be stored for more than a few minutes, and is produced in municipalities at about 2-3atm absolute as a gas.

Some rental companies rent smoke or mold remediation equipment, which may include an ozone generator that draws from the air with a compressor and delivers ozone-containing gas from a tube.

Aquarists use ozone (and UV) in their aquariums for biology control, and their method of application (and cautions) should be similar to what your friend needs.

Production from sulfuric acid will be a whole lot more work than it is worth.  And sulfuric will kill the bugs too!

Your friend should be very careful that he / she does not breathe the ozone gas.  The folks that sterilize water for a living have destruct units to convert ozone back to oxygen.

Perhaps your friend should visit a bottler or municipal water treatment plant nearby that uses ozone instead.  Not only can they get some real goods, but they can start networking for a future occupation.

[flightman233]

Good suggestions here, other places to check may be some retail outlets that sell spa equipment.  In certain areas you can find ozonators (spelling may be wrong) but I know that when I worked in that business we sold some.  Might be worth a shot, but aquariums are probably the better way to for small scale application.

[wuhtzu]

I've passed on your good suggestions - thanks alot!

The aquarium story: Are people, who is into fish and aquariums, using canisters with ozone (which mean my friend could buy those) and some uv lamps to control the biology of their water?

[dlzc]

I've passed on your good suggestions - thanks alot!

The aquarium story: Are people, who is into fish and aquariums, using canisters with ozone (which mean my friend could buy those) and some uv lamps to control the biology of their water?

Already answered.  No.
Liquid ozone (super cold, a dewar like liquid oxygen) has a half life of about a week.  Much less as gas in air, even less if humidity is present.  Ozone spontaneously decays back to oxygen.   Ozone in concentrations of 10 wt% or higher can easily deflagrate, releasing a bit of heat, increasing the number of molecules by 50%, and increasing the pressure.

[wuhtzu]

My friend successfully purchased (his school paid) an "ozone-machine" from a pet store for 1300 DKK (270 USD or 170 EUR).

So thank you for your assistance.

Wuhtzu

[dlzc]

My friend successfully purchased (his school paid) an "ozone-machine" from a pet store for 1300 DKK (270 USD or 170 EUR).

So thank you for your assistance.

Wuhtzu

You are very welcome.

Assuming the ozone machine makes ozone under pressure, the gas will need to be blown into a diffuser stone, and submerged as deeply as possible and still get tiny bubbles from the stone.  If the ozone machine requires an eductor or venturi, then you will need a pump to move water flow through the eductor.  Pool pumps that are inexpensive will not tolerate drawing in water with ozone, so the project will probably have to be limited to a "once through" system.

It is very easy to make ozone, and never manage to dissolve much of it in water.  I wish your friend the best of luck on the project.