Sciencemadness Discussion Board

Veg oil for collecting CO2?

NEMO-Chemistry - 30-3-2017 at 17:42

Hi,
Simple kind of question.......

I would like to measure how much CO2 is produced in some fermentation experiments. While I could 'bubble' the CO2 into a water filled Burette, CO2 dissolves a fair bit in water.

I was wondering if CO2 dissolves or reacts much with Veg oil? Or at a push mineral oil? Or does anyone have a better method? In an ideal world the CO2 needs to be fairly 'harmless', as it will be used after measuring. Ironically by dissolving into water via a fine grade frited funnel.

Thanks

elementcollector1 - 30-3-2017 at 18:00

Mineral oil should work. A potential better way of doing it would be to react the CO2 with something and see how much the weight of that something changes, though I'm unsure what would be the best choice for this.

NEMO-Chemistry - 30-3-2017 at 18:12

Quote: Originally posted by elementcollector1  
Mineral oil should work. A potential better way of doing it would be to react the CO2 with something and see how much the weight of that something changes, though I'm unsure what would be the best choice for this.

If I react it, then I cant use it after measuring it. Its just something I am trying to work out, using yeast to produce CO2. The aim is actually CO2, but at a controlled rate. So the experiment is based around a strong sugar solution slowly dripped into the yeast/water.

Its all sealed off and a aquarium airline one way valve. After its measured I then dissolve it into water and use that.

What I am actually trying to discover, is how much of the sugar solution to add, and at what rate. I need to produce a small but fairly predictable amount, this I could then use directly into a aquarium.

You can buy similar systems, but they are not so controllable, also the advantage of yeast is Ethanol, if you inject the CO2 from the fermenter, directly into a packed column, then into the aquarium water, you get a nitrate filter as well.

Apparently the tiny amounts of Ethanol in the CO2, under anaerobic/ish conditions turn nitrate into nitrogen gas. Or at least reduce the Nitrate.

Its just something I got from some papers and patents, it intrigued me and I wanted to have a look at it.

But at the moment I am wanting to find out how many ml of sugar solution to add every hour, so I can work out roughly how much is needed to make small but steady amounts, if that makes any sense at all!

RogueRose - 30-3-2017 at 21:09

Don't forget the CO2 that remains in the wash, it's difficult to get it all out even with good agitation.

NEMO-Chemistry - 31-3-2017 at 02:38

Quote: Originally posted by RogueRose  
Don't forget the CO2 that remains in the wash, it's difficult to get it all out even with good agitation.
The wash isnt important, for what I am doing it can be ignored.

Booze - 31-3-2017 at 08:49

I use a balloon to capture it temporarily, and then I transfer that to the water bubbler setup. Sometimes I shake it around if I think some carbon dioxide has been dissolved.

NEMO-Chemistry - 1-4-2017 at 03:03

Quote: Originally posted by Booze  
I use a balloon to capture it temporarily, and then I transfer that to the water bubbler setup. Sometimes I shake it around if I think some carbon dioxide has been dissolved.
I dont need every last drop, the idea is simple.

Find out how much solution of X strength sugar solution in Y strength yeast, produces CO2 per hour and at what rate. This is for bubbling into a plant aquarium via a nitrate filter (yes counter productive in a way).


AJKOER - 1-4-2017 at 04:02

A few comments based on my experience working with CO2 and aqueous mixtues (more precisely, the action of CO2 on an aqueous mix of NaOCl/CaCl2/NaCl producing CaCO3 and HOCl/NaCl). First, even for cold solutions in a large compressible plastic container, little happens until the vessel is shaken, at which point the plastic vessel is rapidly compressed.

Use this fact to measure relative volume changes using a very compressible clear plastic bag by observing the volume of water displaced upon placing the bag in a water bath after shaking for a fixed amount of time as compared to pre-shaking.

I say relative as under varying conditions (like temperature, amount of salts dissolved, pressure,...) the amount of CO2 pre-shaking that goes into solution is small and variable.

Use your relative volume measurements to locate near optimal conditions.

[Edited on 1-4-2017 by AJKOER]