CO2 Scrubber Media Optimization

Formulator · Sep 18, 2024

Edit: Replace lye with soda lime below. I’m leaving my original error so there is context for the discussion after where we straightened that out…

I have a theory that the standard geometry of lye pellets (sodium hydroxide pellets) is primarily driven by their use in a variety of industrial applications, rather than being specifically optimized for CO2 removal from air. Sodium hydroxide (lye) is a versatile chemical, and its pellet form is well-suited for many different processes that benefit from this shape.

Given these widespread uses, I would guess lye manufacturers have standardized the pellet geometry to cater to these broader industrial needs, making it cost-effective to produce at scale. Since CO2 removal is a more niche application, lye pellets are simply repurposed for this function, adding a color indicator, but without specific modifications to optimize the shape for surface area or reaction efficiency.

In theory, a product designed specifically for CO2 removal could take on a different form, such as finer particles or engineered shapes to maximize surface area.

I’m really tired of changing my scrubber media every 10 days, so I was thinking about doing some experimenting with various particle sizes to see if there is a significant difference.

Any suggestions or challenges you anticipate? Any disagreement with my synopsis of why I think we are currently stuck with the pellet form?

Pod_01 · Sep 19, 2024

Interesting and I was wondering the same.
I tried few types and found pellets do not impact air flow. I have alternative media that seems to be broken up small chunks (not pellets) and this type definitely impacts airflow when packed. I had to reseal all the connections to make sure the skimmer was getting air from the scrubber not leaks.

I wonder if ROX0.8 type of shape would work better for airflow, removal of CO2 and longer life.

I suspect the air flow through the CO2 scrubber is also critical so there are no dead spaces and all of the media is used up. I don’t think companies are going to spend money or time to create ideal reactor so we are stuck with sub optimal implementation.

I be curious to know if quantity used plays role.
Or is there relation between diameter and height of the reactor/media configuration. Is wide reactor better vs. slender tall configuration.

Good luck,

Danny McElroy · Sep 19, 2024

Formulator said:
I have a theory that the standard geometry of lye pellets (sodium hydroxide pellets) is primarily driven by their use in a variety of industrial applications, rather than being specifically optimized for CO2 removal from air. Sodium hydroxide (lye) is a versatile chemical, and its pellet form is well-suited for many different processes that benefit from this shape.

Given these widespread uses, I would guess lye manufacturers have standardized the pellet geometry to cater to these broader industrial needs, making it cost-effective to produce at scale. Since CO2 removal is a more niche application, lye pellets are simply repurposed for this function, adding a color indicator, but without specific modifications to optimize the shape for surface area or reaction efficiency.

In theory, a product designed specifically for CO2 removal could take on a different form, such as finer particles or engineered shapes to maximize surface area.

I’m really tired of changing my scrubber media every 10 days, so I was thinking about doing some experimenting with various particle sizes to see if there is a significant difference.

Any suggestions or challenges you anticipate? Any disagreement with my synopsis of why I think we are currently stuck with the pellet form?

I think the only challenge is that most manufacturers avoid using lye products due to the inherent danger associated with them, and they don't want the liability associated with it. Reference fight club!!!

.

Randy Holmes-Farley · Sep 19, 2024

Pod_01 said:
Interesting and I was wondering the same.
I tried few types and found pellets do not impact air flow. I have alternative media that seems to be broken up small chunks (not pellets) and this type definitely impacts airflow when packed. I had to reseal all the connections to make sure the skimmer was getting air from the scrubber not leaks.

I wonder if ROX0.8 type of shape would work better for airflow, removal of CO2 and longer life.

I suspect the air flow through the CO2 scrubber is also critical so there are no dead spaces and all of the media is used up. I don’t think companies are going to spend money or time to create ideal reactor so we are stuck with sub optimal implementation.

I be curious to know if quantity used plays role.
Or is there relation between diameter and height of the reactor/media configuration. Is wide reactor better vs. slender tall configuration.

Good luck,

Are you actually talking about lye, or soda lime?

Sodium hydroxide pellets may well just dissolve into a puddle if the humidity is high enough.

Pod_01 · Sep 19, 2024

Randy Holmes-Farley said:
Are you actually talking about lye, or soda lime?

Sodium hydroxide pellets may well just dissolve into a puddle if the humidity is high enough.

Right soda lime, CO2 scrubber media. No puddle in my CO2 scrubber media yet.

I be interested in the optimized soda lime use in the CO2 scrubber.

spsick · Sep 19, 2024

I have found different brands provide different results. BRS media burns faster, has a lower impact on pH, and has a criminally hard to see color change for me compared to Jorvet.

Randy Holmes-Farley · Sep 19, 2024

Pod_01 said:
Right soda lime, CO2 scrubber media. No puddle in my CO2 scrubber media yet.

I be interested in the optimized soda lime use in the CO2 scrubber.

I asked because I assumed Formulator knew the difference and some folks have used sodium hydroxide.

Soda lime is already designed for CO2 removal, so I would not expect a shape change will make a big difference.

Formulator · Sep 19, 2024

Danny McElroy said:
Reference fight club!!!

Funny you say that - I imagine I’m Tyler Durden every time I refill my scrubber

Formulator · Sep 19, 2024

Randy Holmes-Farley said:
Are you actually talking about lye, or soda lime?

Sodium hydroxide pellets may well just dissolve into a puddle if the humidity is high enough.

Yes, I meant soda lime! Thank you for the clarification! Sorry for the confusion all. I’m not sure why I got lye in my head… Maybe it was the fight club reference

Formulator · Sep 19, 2024

Randy Holmes-Farley said:
Soda lime is already designed for CO2 removal, so I would not expect a shape change will make a big difference.

Is this true? I assumed the pellet shape was just easy to manufacture. I imagine there are still many other industrial applications for soda lime, similarly to lye.

Randy Holmes-Farley · Sep 19, 2024

Formulator said:
Is this true? I assumed the pellet shape was just easy to manufacture. I imagine there are still many other industrial applications for soda lime, similarly to lye.

I think a lot of it is used in anesthesia.

Soda lime - Wikipedia

en.m.wikipedia.org

Formulator · Sep 19, 2024

Randy Holmes-Farley said:
I think a lot of it is used in anesthesia.

Soda lime - Wikipedia

en.m.wikipedia.org

I’m still skeptical that the geometry has been optimized for longer term applications. When it is only needed for a few hours or maybe a day in surgery or for diving, then thrown away, the shape is much less important because it probably rarely gets used to exhaustion. But in our hobby, we want to get as much life as possible. Maybe I’m wrong, but I might play around with it to see for myself if there is any significant improvement to be had or not.