DI Regeneration

[Garf]

I've been regenerating my DI resins for 10 years, but have found information that both GFO (chemical regen) and activated carbon (microwave regen) can also be regenerated. Has anyone tried it?

[Ace25]

Stumbled on those last year.. nope, seems like too much effort to me, but every person has to weigh their own cost to benefits. GFO regen works but the carbon regen I heard doesn't work, even in a kiln you can only clean so much of it, so if is last 7 days new, after regen only last 3 days because it can't cook out/unclog all the pores.

[CHOMPERS]

Can you post the links you have? I'm interested in regenerating all three. I had found a teacher that was begging for everyones used carbon, so it occurred to me that there must be a regeneration procedure but didn't find anything. Just recently, I found a proceedure for the GFO.

[CHOMPERS]

http://www.advancedaquarist.com/2010/10/chemistry

http://www.alibaba.com/product-free/..._RE_CYCLE.html

[CHOMPERS]

http://alcoholpurification.com/recyc...ivated-carbon/

I found this by searching "activated carbon recycling" rather than "regeneration".

[Garf]

Here's how I regenerate DI resin;

You need a few things first. Spent mixed bed resin, Hydrochloric Acid 16%, Sodium Hydroxide 16%'. Couple of jugs, old spoon, 20 ltrs RO (preferably RODI - the cleaner the better).





First pour in SODIUM HYDROXIDE into the spent resin. This acts as a separating agent and a regenerant for the ANION RESIN.





Stir the resins with an old metal spoon for a few seconds and put the container out of the way for an hour or so (you do not want to accidentally spill or splash these chemicals, they are sufficiently strong to cause real damage). You will notice that the two types of resins (CATION and ANION) separate, with the CATION at the bottom whilst the ANION floats to the top as regeneration is underway.





After a further small stir, leave it for ten minutes or so then pour off the ANION resin into another container slowly (try not to get the CATION into the ANION). You should end up with two containers (pale one ANION, dark one CATION).





The pale one is now regenerating (stir every 30 minutes) in the SODIUM HYDROXIDE that was used to separate the resins. The CATION requires a few extra steps though.
1). Rinse the CATION (dark one) with tap water to remove all traces of Sodium Hydroxide (fill the jug give it a stir, empty the water, then repeat about 10 times)
2). Add HYDROCHLORIC ACID to the CATION RESIN (dark one)
3). Put container somewhere safe and stir it every 30 minutes, for a couple of hours.


Now the resins have regenerated, rinse each one with RO or RODI (you can use tap water but this drastically reduces the life of the newly regenerated resins). I suggest using about 10 litres to rinse each resin (filling the jug, quick stir then ditching the water [ x10ish]) works best (the anion needs more water in so that the resin sinks. Each subsequent rinse becomes easier as the resin sinks faster with each rinse).


Now recombine the two recharged resins and stir thoroughly so the beads are well and truly mixed together and your ready to reload the resin chamber.


Run 10 litres of RO through the chamber whilst connected to the RO unit and discard. Job done. Sounds more complicated than it is, after a few regenerations it takes next to no time, as the majority of the time is just waiting for the regenerants to do there job.

[Garf]

GFO regeneration test.


1 litre of 1M (ish) sodium hydroxide solution (150mls 16% NaOH in 1 litre RODI), exhausted GFO. Leave the regenerant to replace phosphate ions with hyroxyl ions on the binding sites of the GFO is the first stage. This takes 3 days with an occassional gentle mix.





After 3 days I will dilute the regenerant (1:100) so that I can test for phosphate presence, therefore indicating its effectiveness. Then I need to rinse the GFO.

[Garf]

Tested the regenerant (used 4.5 litres in total), took samples from each 1.5 litre batch and averaged the reading after neutralisation with a few mls of HCL.





Got a reading of 1.1ppm (diluted by 200), so 220ppm in 4.5ltrs is 2.2ppm in a 450 litre tank from 250grms of GFO. So now this regenerated GFO is capable of removing another 2.2ppm (450 ltr tank), over time. The regenerated GFO shows no to little degradation.


All that's needed now is a bloody good rinse in lots of RODI, as described in the above link, and it's done, almost free of cost. Gonna rinse slowly, over next few days with about 20ltrs RODI to be sure, then test it.

[Garf]

Returned the GFO to the tank, pH remained stable. Conclusion, it works.

Next to test the CARBON regeneration as linked by Chompers, thanks. There is also a microwave version which I'll get around to sooner or later.

[Garf]

Found a patent that makes lots of sense for activated carbon regeneration, sodium hydroxide (1 to 4%), ethanol (10 to 40%) remainder water, then soaked and boiled for 6 to 24hrs (more boiling, the better the results).
http://www.freepatentsonline.com/6423657.html