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Topic: Hot water and activated carbon filters  (Read 19034 times)

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Offline Alexander28

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Hot water and activated carbon filters
« on: July 05, 2013, 09:28:35 AM »
Hello forum members,

I'm designing a product that requires me to filter hot water (directly from a kettle) into a bottle, whilst taking out the chlorine. Activated carbon filters initially seemed to be the solution until I read that they are damaged when used with hot water. So my question is: Are there any other methods that would allow for filtration of hot (boiling) tap water? It would be great if the product could be placed on top of a bottle or serve as other kind of adapter. Could Coconut Shell Activated Carbon maybe offer a solution? Any help would be much appreciated.

Thank You,

Alexander

Offline curiouscat

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Re: Hot water and activated carbon filters
« Reply #1 on: July 05, 2013, 09:52:11 AM »
I could be wrong, but I'm surprised if activated carbon was damaged by regular hot water.

The activation process often uses T that's way higher.

Offline Alexander28

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Re: Hot water and activated carbon filters
« Reply #2 on: July 06, 2013, 12:35:10 AM »
Thanks curiouscat, I must say the web is rather vague on this matter.

This is one of the texts that notes the dangers of using activated carbon filters with hot water:

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It is important to note, particularly when using counter-top and faucet-mount carbon filtration systems, that hot water should NEVER be run through a carbon filter. I have seen warnings about possible damage to the filter from hot water. Perhaps more importantly, hot water will tend to release trapped contaminants into the water flow potentially making the water coming out of the filter more contaminated than the water going in.
  Source: http://www.belkraft.com/gac.htm

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The lone exception to this rule is carbon mixed with KDF 55.
Source: http://www.advancedwaterfilters.com/faq.php?q_id=10

The reason why I mentioned activated carbon from coconut shells is because it is treated with hot water/vapor, but the same problem might apply. As for KDF 55, could some-one maybe confirm this?

Offline Arkcon

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Re: Hot water and activated carbon filters
« Reply #3 on: July 06, 2013, 06:46:09 AM »
More likely, the integrity of the packing in the household faucet filters is damaged by hot water, or the other components of the filtration system are heat sensitive.  This is not a chemical explanation.

Try to realize that absorption onto these exchange media (the carbon particles and the other media in the faucet filter) is an equilibrium process.  The filter doesn't hold things forever in some never-land space.  Once on the surface, things can come off.  When there are traces of contaminants in the water, and the media is new, practically all sticks to the media.  As the media gets full, it may start to leach contaminants out.  I can't prove it, but its reasonable to assume that at higher temps, all such reactions happen faster  -- adsorbing and releasing.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline curiouscat

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Re: Hot water and activated carbon filters
« Reply #4 on: July 06, 2013, 08:53:53 AM »
More likely, the integrity of the packing in the household faucet filters is damaged by hot water, or the other components of the filtration system are heat sensitive.  This is not a chemical explanation.

This.

If you are designing your own product you can use the right casing materials. Act C by itself ought to be ok.

Try it out?

Offline Alexander28

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Re: Hot water and activated carbon filters
« Reply #5 on: July 07, 2013, 01:41:25 AM »
@Arcon: Your point is supported by this statement

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hot water should NEVER be run through a carbon filter, because hot water will tend to release trapped contaminants into the water flow potentially making the water leaving the filter more contaminated than the water going in.
http://www.advancedwaterfilters.com/faq.php?q_id=10

So the question is: How could you stop this process?

@curiouscat: Would you have suggestions for the right casing materials?

Offline curiouscat

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Re: Hot water and activated carbon filters
« Reply #6 on: July 07, 2013, 01:49:39 AM »
@curiouscat: Would you have suggestions for the right casing materials?

Stainless Steel. Works great at 100 C. Cheap too.

Easy to form, weld n machine.


Offline curiouscat

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Re: Hot water and activated carbon filters
« Reply #7 on: July 07, 2013, 02:00:17 AM »
@Arcon: Your point is supported by this statement

Quote
hot water should NEVER be run through a carbon filter, because hot water will tend to release trapped contaminants into the water flow potentially making the water leaving the filter more contaminated than the water going in.
http://www.advancedwaterfilters.com/faq.php?q_id=10

So the question is: How could you stop this process?


I think you are looking at it the wrong way. There's nothing magic that happens at 100 C. Just that the equilibrium now more favors the impurities in the water than on Carbon. Hence if you had Carbon that was working and 30 C and suddenly passed hot water through it, the carbon is now above its saturation capacity. So it dumps impurities into the hot water.

This by itself  doesn't preclude using the Carbon in 100 C water as a filter. Just that it will get used up sooner. It'll have a lower adsorption capacity than if you were using it at 30 C.

Offline Alexander28

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Re: Hot water and activated carbon filters
« Reply #8 on: July 07, 2013, 08:06:22 AM »
@curiouscat
Stainless steel, how could I forget! Thanks :)


I think you are looking at it the wrong way. There's nothing magic that happens at 100 C. Just that the equilibrium now more favors the impurities in the water than on Carbon. Hence if you had Carbon that was working and 30 C and suddenly passed hot water through it, the carbon is now above its saturation capacity. So it dumps impurities into the hot water.

This by itself  doesn't preclude using the Carbon in 100 C water as a filter. Just that it will get used up sooner. It'll have a lower adsorption capacity than if you were using it at 30 C.

From: http://www.espring.com/english/ibocenter/documents/eSpring_ProductGde_2_04.pdf:

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Tests have shown that optimal removal and adsorption efficiency occur when
the water is at an average 25° C temperature. Higher temperatures will reduce filter efficiency.
Contaminants remain bonded to carbon in cool water. When exposed to hot water, some difficult-to-remove
contaminants may detach from the carbon and enter the treated water stream. Finally, the use of hot
water may cause the structural integrity of the unit to be compromised.

So I believe you're right that the filter wont last as long (the last structural integrity bit), but using hot water would also release contaminants that have previously been captured by the membranes in the filter - I believe that was the point made by Arkcon.

At this stage I think and will assume that the membranes will release particles at higher temperatures (sorry for being stubborn but the sources Ive mentioned so far seem to back this), question remains: How can this be stopped?

Offline Carterofmars

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Re: Hot water and activated carbon filters
« Reply #9 on: March 02, 2015, 05:47:34 AM »
Hi-

Question concerning runnning hot water through a carbon filter.  I'm using a product called BluPure http://blupure.com/13-Stage-Water-Filter .  Ive run hot water through this unit several times for a minute at a time.

1. Have I compromised the effectiveness of the unit permanently?
2. Speaking about the release of contaminants in the active carbon, is that only as the hot water is being run through, and the active carbon will catch contaminants again once cold water usage is resumed?

I'm just wondering if It's safe to continue using.  Or, if I should just replace the carbon canister.

Thanks in advance and sorry to drudge up an old string.

Offline Arkcon

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Re: Hot water and activated carbon filters
« Reply #10 on: March 02, 2015, 09:31:19 AM »
No problem with the thread bμmp, its good to have everything together when we talk about something new.  I really can't say if a little bit of hot water will ruin the media, or not.  Most likely the solid media meant to provide filtration may expand and crack if abused.  But these things are meant to be disposable, anyway.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

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