Amberlite IRA-900 chloride Sodium Phosphate Prep Test

Based on the conversations with Dr. Xiaoyang Shi (AKA Yang), who’s doing a postdoc at Columbia University, we’re testing whether Amberlite IRA-900 Chloride is more efficient at capturing and releasing CO2 when prepped with sodium phosphate instead of sodium carbonate. In our first test, we’re using .5m tribasic sodium phosphate solution.

Step 1) 48 hour hot soak 40gs of the amberlite in 500 ml of distilled water at 85C (there might have been a slight issue here, most of the water seemed to boil off during the soak, not sure why, maybe due to higher temperature from earlier soaks or the new setup):

To maintain the temperature, used a manual slow cooker with a DorkFood DSV to keep the temperature at 85C for 48 hours.

Step 2) combined 500 ml of distilled water and 95.03 grams of sodium phosphate to create the washing solution. Soaked the amberlite and stirred it for at least 12 hours (ended up being much longer) as per Yang’s instructions.

Note: On the plus side, the sodium phosphate doesn’t become still and difficult to desolve in the water. On the downside, you need 95.03g to make a .5 molar solution with 500ml of water.

After the initial soak, tested the solution for chloride levels, pretty similar to what we’ve seen with the sodium carbonate (over 2000ppm chloride):

Still on step 2, second wash cycle complete, about 1000 ppm chloride lower:

Here’s the chart for the 3rd wash:

Here’s the chart for the 4 and 5th wash:

To summarize, I’ve done 5 washes and here’s the chloride level after each one:

1: 2170ppm
2: 1035ppm
3: 627ppm
4: 625ppm
5: 315ppm

That 4th was seems fishy to me (maybe a sensor issue? Or maybe human error), but it seems clear there’s still more chlorine to remove.

Ordered more sodium phosphate and tried the first test with the sodium phosphate with treated Amberlite. The results are…not spectacular:


Raw data is here in the “04.27.2022 - 1 gram Amberlite w SP, not fully prep” tab.

That’s 1 gram of CO2 in the standard sorbent tester. No increase in CO2 ppm. So, I think we have to conclude it’s not prepped enough, but I’m surprised we didn’t see any reaction at all.

Completed wash 6: 270ppm chloride

Still a significant amount of chloride in the water, running another wash now.

Also running a test on the chloride levels of the solution prewash. Should have those results this afternoon.

Completed 2 more washes.

Wash 7: 260ppm chloride
Wash 8: 193ppm chloride

So…getting there, I guess? Doing another wash now.

Wash 9: 160 ppm

Moving on to wash 10, but at that point I’ve used almost 1kg of sodium phosphate in an attempt to prep 40 grams of amberlite…

Wash 10: 240ppm

Um, what? I did leave this one sitting in the solution a little longer, like 36 hours… but still. This is confusing.

Wash 11: 182ppm

Starting to suspect maybe there’s an issue with the chloride sensor? I’m going to do some tests with some know quantities of chloride ppm.