> chemistry > techniques-et-matériel > how-to-regenerate-deionization-resin-for-use-in-reverse-osmosis-deionization-systems-nurdrage

How to Regenerate Deionization Resin for Use in Reverse Osmosis Deionization Systems

NurdRage - 2020-07-05

In this video we show how to Regenerate Mixed-Bed Deionization Resin for Use in Reverse Osmosis Deionization systems.

A reverse osmosis deionization system purifies water by first subjecting it to reverse osmosis to remove most of the minerals, and then passing it through a column of deionization resin to remove at leftovers. This resin has a very limited capacity and often represents the most expensive recurring cost of such systems. Normally they are discarded when spent, but can be regenerated chemically.

First a 15% solution of sodium hydroxide is prepared by mixing water and sodium hydroxide in a 3/17 ratio by mass. So for 170g of water, 30g of sodium hydroxide are added. This solution is added to spent deionization resin (80mL-200mL). The anion exchange resin component will float to the top while the cation exchange resin component sinks to the bottom. The solution also regenerates the anion exchange resin. The two resins are separate by pouring. The anion exchange resin is repeatedly washed with deionized water. The cation exchange resin is washed a few times with equal volumes of water and then regenerated by mixing with a equal volume of 5% hydrochloric acid (made by mixing 30% hydrochloric acid in a 1:4 ratio with water). After letting it sit for an hour, the cation exchange resin is filtered and also washed repeatedly with deionized water.

The two resins are now regenerated and can be recombined to make mixed-bed deionization resin. 

#deionization #resin #regeneration

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NurdRage - 2020-07-05

Answer to a common question that keeps coming up:

Separating and remixing the resin seems redundant, can time and labor be saved by keeping the resins separate during use and regenerating them in independent cycles?

Actually yes, you can save time and labor by using separate deionization beds, but there are some caveats.

 So for those of you that don't know, since the resin beads work independently, you don't strictly need to mix them. Instead two different cartridges can be made, one containing anion exchange resin and the other containing cation exchange resin. They are installed in separate housings and connected in series. As the water flows through one the corresponding ions are removed, and then as they flow through the next cartridge, the ions of that type are removed. The result is deionized water just as with a mixed bed. But the system is much easier to regenerate as the resins are already separated and it's just a matter of removing the appropriate resin, mixing it with regenerant, washing it, and putting it back. In fact a number of commercial systems indeed do it this way. And you can set your system up this way as well.

The reason why it's not the standard is because it actually produces slightly lower purity water. This is because as you replace ions you shift the equilibrium of the reaction and some of it shifts back.
For example, let's say we have a solution of sodium chloride salt water and we run through a cation exchange resin already loaded with hydronium ions. The result is the sodium ions are swapped out for hydronium ions making hydrochloric acid. But as we know from before, hydrochloric acid will actually regenerate the resin and swap out sodium ions making salt again. Fortunately the effect is very small since the concentration of hydrochloric acid produced is very low. The actual equilibrium will lie very far to the right. But the effect isn't zero.

The tiny amount of sodium that remains will pass through the anion exchange column without being absorbed. Meanwhile, most of the chloride will be removed but again, not all for a similar reason of equilibrium. To improve this you need to have another cation exchange resin column that now removes the remaining sodium ions. Since the most of chloride was removed by the anion exchange resin the amount of hydrochloric acid produced is lower so you get improved water quality. But it still isn't zero, you need to keep stacking more and more pairs.

A mixed bed deionization resin column solves this by essentially having hundreds of deionization pairs in one column. The leftover ions from one bead of resin are removed by the next bead, and the leftovers from that bead are absorbed by a bead further down. So mixed bed resins give the best performance for the least complication. And thus remain the standard for water deionization.

However there is a way to get the benefits of a mixed bed deionization column and still have the slightly easier maintenance of separate beds, and that's to use both. First have the anion and cation exchange columns processing the incoming water, and then have a final mixed bed column to polish the tiny percentage that makes it through. As long as you keep regenerating the anion and cation exchange columns before they are completely depleted, you can get many months of use out of the mixed bed column before it needs to be regenerated.

 Personally though, i don't bother. Separating and remixing the resin isn't the most labor intensive part of this process and i don't regenerate my resin often enough anyway to be bothered by it.

AlucardPawpad ClownWorld - 2020-07-06

@Rúna Kovács Some of those may have been in parallel for higher throughput? Or they needed very very high purity. hmm.

Christopher Wilson - 2020-07-07

why do you still pretend to be nurdrage when its so obvious you're nilered

Benjamin Shropshire - 2020-07-08

Exactly the question I was going to ask. But it does moot yet another: in industrial environments, do they even bother swapping out the cartridges for the regeneration process or can it be done with bypass valves? Stack a dozen or so single resin pairs in a row with more than you really need and you can always have one in bypass at some phase of the regeneration process.

Rúna Kovács - 2020-07-08

@Benjamin Shropshire I was taught they use bypass valves.

Imagine a big tank with multiple pipes leading into it. One for normal operations, one for rinsing with DI water, one for regeneration.

And IIRC, the way it works (it's been a while since I studied/interned on the plant-level) is to flush one column into the next and only at the end clear the waste fluid.

bknesheim - 2020-07-09

"The reason why it's not the standard is because it actually produces slightly lower purity water."
Could you not fix this using a third mixed cartridges after two with different resins. Since it only have to remove any small amounts that slipt through the two other cartridges it should last a long time.

NurdRage - 2020-07-05

Still rebuilding the lab. Might do some electroplating, or revisit making nitric acid (my last video on nitric acid is a decade old).

Ellipsis Realty - 2020-07-09

Birkeland-Eyde process style Nitric Acid!

Tylr Vncnt - 2020-07-10


ZoonCrypticon - 2020-07-19

Hello NurdRage!
1. Could you one day show how to produce H2O2 with different methods, as hydrogen peroxide is so often used in various processes.
2. And my next question would be, if you can synthesize phtalic acid (and later the anhydride of it for luminol) out of naphthalene?
Thank you for all your videos!!

Karl Fischer - 2020-07-24

Suggestion, the partial oxidation of a primary alcohol to an aldehyde, many have the demonstration or common experiment on you tube using acidified dichromate or permanganate, although another preparation needs the vapour of ethanol to be passed over hot copper turnings at 300 C. These is no real video or assessment of this method to produce acetaldehyde, could you maybe do it for an upcoming video? Regards, Karl

孙子龙 - 2020-07-30

When will you update your bilibili channel

Mary Udomah - 2020-07-06

Me: Doesn’t understand a word of the title
Also me: Watches with complete and utter interest anyways

Stephen Gillie - 2020-07-11

Cations are positive and I remember that because "cats are a plus".

75Bird455 - 2020-07-05

This is what my dad does for a living, since 1990, on a rather large scale.

hamster1 - 2020-12-27

Good for him saving the environment 👍 if no one regens resin it just goes in the bin

TheBackyardChemist - 2020-07-05

2:10 The nitrogen atom on the right has an OH group instead of a methyl, not sure if intentional or not.

NurdRage - 2020-07-05

Yup, that's wrong. I'll fix for a future video.

margonaaaa - 2020-07-05

الله احيان عاباالي

Stephen Gillie - 2020-07-11

He says "hydronium" but shows hydrogen several times. Hydronium is H3O, but H+ is shown.

Exe Csrss - 2020-07-24

@Stephen Gillie H+ doesn't really exist because it's just a proton and very small. So it quickly interacts with water (which functions as a lewis base) and forms H3O+, hydronium. However for the sake of simplicity, It is common to show it as H+, because the water molecule just acts as a stabiliser for the hydron ion and the water is regenerated after the hydronium ion interacts with any base

Chicken dog - 2020-07-06

That is the best quote ever "this fluid is somewhat corrosive to human flesh"

Stephen Gillie - 2020-07-11

It's as corrosive as soap. NileRed stuck his hand in it once, and nothing happened.

Nathan Klaft - 2020-07-05

Id love to see some polymer chemistry.
never gets much love or exploration.

Francesca Pellegrino - 2020-07-05

This polymer processing engineer agrees!

CryptoPhoenix - 2020-07-05

I did my training period in polymer chemistry lab and synthesized thermoresponsive polymers. Functional polymers are actually very useful and fascinating!

Blzt - 2020-07-05

polymer? I barely know her

jogandsp - 2020-07-06

That's because it has some very big challenges

Zazaaji - 2020-07-05

Ah yes, the truly professional way of storing things that you just spent hours preparing. I really love how youäve always used whatever you have on-hand to do so many of your things with. Easily one of my favorite things about you.

Kineth1 - 2020-07-06

I really like it as well, I do barely any chemistry, but I appreciate his effort to bring professional techniques together with amateur equipment.

jared levy - 2020-07-05

You're back!

Jason Patterson - 2020-07-05

Propel "Fitness Water" bottles are perfect for DIY separatory funnels. The top of the bottle is already spout shaped and it's clear as well.

They also make AMAZING alcohol vapor rockets when used for the "whoosh bottle" demonstration, as the spout acts just like a rocket nozzle. Use a ring stand or similar to make sure that they fly upward instead of sideways and assume anything underneath is going to catch fire from alcohol.

revenevan11 - 2020-07-06

Wow, a fitting name for that demonstration too!
(I've had it and thus heard the name before but haven't tried that experiment and don't have any bottles lying around)

Jason Patterson - 2020-07-06

@revenevan11 It's pretty impressive. There is one poor ceiling tile in my classroom with chunks out of it from being hit by a Propel bottle dozens of times. If you try it, be smart about your hands, face, and the surroundings.

Lossanaght - 2020-07-05

Would there be any value in keeping most of the already separated resin as an easily in-situ regenerated dual bed to do the bulk deionization and use the remainder as a mixed bed for final cleanup of the ions?

NurdRage - 2020-07-05

go for it

Dan Heidel - 2020-07-06

That is actually a good way to do it. I built a system in an old lab with separate color indicating anion and cation beds and a polishing step with mixed breed nuclear grade resin. The system consistently put out >1 megaohm water at 2gpm. Didn't need the ro step since the incoming water was fairly high quality. I would recommend having physical filters (1 um gradient spun yarn filters work well) and a uv sterilizer and at least 1 activated carbon block upstream if the resins. The water coming out of the system was very low toc and was deionized enough that it completely after away a stainless steel temperature probably in a few months.

RicoElectrico - 2020-07-06

@Dan Heidel > was deionized enough that it completely after away a stainless steel temperature probably in a few months.
Did you mean: completely ate away a stainless steel temperature probe?

Cat22 - 2020-07-09

That's what happens when people post from phones - you end up with a lot of gibberish.

72polara - 2020-07-05

This answered many questions I had on regeneration. Worked with equipment (servicing electronic controls) with ion exchange resin many years ago and never really understood how it worked until now.

Flederratte - 2020-07-05

Nice video! I appreciate it very much that you are back!
Oh I would love a new video on nitric acid!

Greetings from Germany. Have a nice week!

ProjectPhysX - 2020-07-05

The density separation is ingenious!

Marta - 2020-07-06

11:40 Professor, I have a question...
11:49 ...oh, I guess I don't.
Thank you for the valuable lecture!

saimon174666 - 2020-07-06

I really enjoy vids I can replicate at home quite easily. Not that I had a reverse osmosis filter, but still..

Brandon Laumer - 2020-07-06

I forgot how much i enjoyed watching videos that go completely over my head....

Curmudgeon - 2020-07-06

I watch these videos to make myself feel smarter.

Ferris Whitehouse - 2020-07-06

Would it be possible to make an ion selective membrane with this stuff? For a battery separator for example?

US - 2020-07-05

I’ve been keeping these, seems like a fun project

Bim - 2020-07-05

Very cool video, I haven't watched for a year or two; good to see that you're still going strong. Love the content, hope to see you at a million before the new year!

Alexander Sannikov - 2020-07-07

although simple, i liked the ingenuity of separation stage using a liquid of intermediate density

EnhancedNightmare - 2020-07-06

I remember getting kilos of used resin from navy base xD

Lester W - 2020-07-06

I would love to see an attempt at an amateur production of a proton exchange membrane. Love this channel, keep up the good work!

R Johnson - 2020-09-23

Thank you!
I keep being amazed at how you manage to pack so much relevant information into the videos, explained in a way that a novice can understand.

frollard - 2020-07-06

Thank you for always sharing and being awesome. I want to mess with this and I don't even have an RO system...just looks like fun.

Uroš Golob - 2020-07-06

Dude thanks, I have been thinking on getting RO system for brewery needs but unavailability of spare cartages does not make it a wise purchase. Regeneration of at least one part of the system might make it viable for me. Will research further.

Erin Lux - 2020-07-06

Me, fascinated but not understanding at all: Ah yes i see

S P - 2020-08-31

Excellent video! Thanks for the presentation.

I have a question though, what do you do to dispose of the regenerant? Pour it down the drain??

A - 2020-07-05

Very in depth and interesting!!

edgeeffect - 2020-07-05

Reaching zero TDS can be a little bit tedious??? ;)

Felipe2077 - 2020-07-05

Is it possible that after the regeneration(s), resin will slowly leach out of the system, and end up in the deionized water? How could that affect future chemical reactions?

Edit: NEVERMIND, you answered this at 11:50 .

TeDeO - 2020-07-06

Title: exists
Me: yes...

RicoElectrico - 2020-07-06

You never cease to amaze me after all the years on YouTube. No complete lab? No problem! :)

erik61801 - 2020-07-06

sweet. been waiting for this.

Kaleb S. - 2020-07-05

This is awesome, had no idea such a thing was possible!

Alexander Van Graff - 2020-07-07

NerdRage content is one of my favorite birthday presents (July 5th) and I got GLASS this year too

Cheryl Dawson - 2020-07-06

I just thought that i hadn't seen a NurdRage video in a while... then lo and behold a New Video!! YAY!

pjwarez - 2020-07-29

NurdRage - Love your videos!!! I watch them all the time. Can I ask, what degree do you hold and where did you obtain it? Just curious.
Wish I knew even 1/5th of what you know.

Zazaaji - 2020-07-05

In this video: Chemist cleans Caviar!
Joking aside, it really amazes me how similar looking it is... Donät get me wrong, I donät think Iäve ever once owned caviar muchless know what it tastes like, but you must admit it looks very similar to all the depictions of caviar youäve seen.

krazieboy03 - 2020-10-28

If i want to do this in larger quantities, what do you recommend for containers? I run DI water system for car washes at home, and would be interested in doing like 5-10lb at once to save on time. Also what is the proper way to dispose of the chemicals after? I'm not a chemist, but looking for ways to cut resin cost. thanks! great video btw!

NurdRage - 2020-10-29

Plastic buckets is fine for containers, for car wash use, you don't need ultra-high purity like a laboratory. Just be sure to wear elbow high dish washing gloves when handling the chemicals. When you're done, you can mix all the waste chemical solutions and add in some (like half a cup per bucket) baking soda. If it fizzes, stir it until dissolved then add in another half cup of baking soda. Keep doing this until it stops fizzing. At that point it's safe enough to dump down the drain (it has essentially become salt).

Pro Killer Minecraft - 2020-12-15

Heh. 9€ is a cost of 1l of resin around here. Lasts for 2 loads. Is itworth needing around with this lab?

Mega Haker - 2020-07-08

Hello i want to ask about ion exchange Separation for very simular metal for exemple :
Rare earth , nikel cobalt and copper, alkalie metal .
And thanks😄

aga - 2020-07-05

Marvellous Chemistry, and Useful too ! Nice one Nurdy :)

Baba Joey - 2020-07-12

hi thank you for all this teaching and sharing i have one question what chemistry book do you recommend us to buy thanks

Bessie Hillum - 2020-07-31

This choice of experiment provided an excellent visual demonstration of what you were trying to achieve, it was really inspiring and easy to understand for the layman.

Grungort - 2020-07-08

finally I know how to do this

Sebas - 2020-07-05

I have never even thought about havig reverse osmosis water in my house until 4 days ago when I bought a marine tank that will need RO water

Cat22 - 2020-07-09

The deionized water is also ideal for things like topping up your car radiator and old style car batteries among other things. For your marine tank its a must but its a good investment too

Johnathan Corgan - 2020-07-05

Suggestion: please do di-nitration of phenol or some other substituted benzene. Lots of videos on mono- or tri-nitration (keep it cold or let it rip), but I don't think I've ever seen a youtube video on the controlled process of di-nitration and how to deal with excessive side-reactions, etc.

Andrew Villalobos - 2020-07-06

Yea I like this idea! I made lots of lower nitrates when using crappy nitrates for picric acid and the lower nitrates all were similar but had slightly different melting points and color. To make mono and di nitrophenol you'd just need more dilute acids and lower temps. NileRed actually made mono nitrophenol in order to make tylenol from aspirin.

Bartosz - 2020-07-14

... acid? Can You imagine that using a lot of acid to this: https://www.youtube.com/watch?v=G66IR8kS0uQ here is used a salt NaCl brine not acid.