PO4x4 = iron based polymer?

[Acrotrdco]

Just found this new product called PO4x4, it said it's a "unique chemical engineered polymer based mini pellets" that has all the advantages of GFO but will not leak iron ion into the water column, and will not clump together, etc.

It can also be "generated" by using the "regeneration powder" which is corrosive, sounds pretty much like regenerating GFO with NaOH!

Any idea what this might be, and if their claim of GFO will leak iron ion into water column is true? (i.e. they claimed "Almost every other iron based GFO is releasing iron-ions to the water up to 10 times more than natural seawater levels. This is tested and confirmed at the university of Wageningen, Holland. The tests were done with a inductively coupled plasma mass spectrometer.")

[Randy Holmes-Farley]

It is just a polymer coated version of regular GFO pellets. You can regenerate normal GFO, and I'm not convinced the iron release part is true or any different than regular GFO. No polymer coating is selective to passage of phosphate and not iron. They probably took the idea that physical chunks do not break off as readily, and intentionally or unintentionally "misinterpreted" that to read as iron.

I do not doubt that GFO releases soluble iron. I also do not consider that a problem. I add iron to my system.

[jtma508]

Being the perennial 'early-adopter' I ordered some of this recently. Still going through Customs I'm told. I'll let you know if it really does out-perform regualr old BRS GFO.

[Randy Holmes-Farley]

FWIW, there are other brands that also sell such products and have been around a while. One, which seemingly stole the picture I drew of a phosphate molecule for their label, is shown in this link:

http://www.polyplab.com/3-opti-phos.php

"Opti-Phos is a revolutionary phosphate removal media made from hydrous ferric oxide (HFO) infused into a synthetic bead."

Note the label:



and the picture from one of my phosphate articles:

Phosphate and the Reef Aquarium
http://reefkeeping.com/issues/2006-09/rhf/index.php

[Acrotrdco]

Thanks Randy, in that case, I might try getting some after my GFO ran out, to see how they behave in a GFO reactor.

Cheers.

[Randy Holmes-Farley]

OK, if you get it, let us know how it works out.

[Acrotrdco]

Just got my package today, here's my report:

Packaging - you can see the beads, very uniform size.


Checking my PO4 before testing the PO4x4, using low-range test with my Salifert test kit (using double sample and tester volume), I guess I could say it's between 0.00 and 0.015ppm


Opened package, used about 50ml and added about 150ml RO/DI water, surprised how clear it is, I don't really need to rinse it!


Putting it in a mesh bag and throw it into my reactor, replacing the GFO I was using.

That's it for now, it'll take weeks if not months to test out how well this PO4x4 works, and if it stand up to its claims

[Randy Holmes-Farley]

Thanks for the update.

[2thdeekay]

What size are the beads? Are they uniformly round? Thanks!

[HighlandReefer]

Does this article represent the mechanisms that these products are using to remove phosphate?


Hybrid anion exchanger for trace phosphate removal from water and wastewater
http://www.sciencedirect.com/science...7&searchtype=a


Lee M. Blaneya, Suna Cinara and Arup K. SenGupta, a,

aDepartment of Civil and Environmental Engineering, Lehigh University, 13 East Packer Avenue, Bethlehem, PA 18015, USA

Received 30 October 2006; revised 20 December 2006; accepted 3 January 2007. Available online 16 February 2007.

Abstract

Throughout recent decades, the wastewater treatment industry has identified the discharge of nutrients, including phosphates and nitrates, into waterways as a risk to natural environments due to the serious effects of eutrophication. For this reason, new tertiary treatment processes have abounded; these processes generally utilize physico–chemical and biological methods to remove nutrients from secondary wastewaters. The disadvantages of such methods involve larger reactor volumes, operating costs, and waste sludge production; furthermore, complete nutrient removal is unattainable due to thermodynamic and kinetic limitations. The subject study presents the development and performance of a new phosphate-selective sorbent, referred to as hybrid anion exchanger or HAIX. HAIX combines durability and mechanical strength of polymeric anion exchange resins with high sorption affinity of hydrated ferric oxide (HFO) toward phosphate. HAIX is essentially a polymeric anion exchanger within which HFO nanoparticles have been dispersed irreversibly. Laboratory studies show that HAIX selectively removes phosphate from the background of much higher concentrations of competing sulfate, chloride and bicarbonate anions due to the combined presence of Coulombic and Lewis acid–base interactions. Experimental results demonstrate that HAIX's phosphate–sulfate separation factor is over two orders of magnitude greater than that of currently available commercial ion exchange resins. Additionally, optimal HAIX performance occurs at typical secondary wastewater pH conditions i.e., around 7.5. HAIX is amenable to efficient regeneration and reuse with no noticeable loss in capacity.

[2thdeekay]

Does this article represent the mechanisms that these products are using to remove phosphate?

I wondered that too. Is it (bead)-CH2-N(CH3)2 / FeO(OH) or something else?

[Randy Holmes-Farley]

It may be, but I thought it is simply encapsulated GFO (but don't know that for sure). The anion resins are not useful for phosphate in seawater (I've tried the best known phosphate binding polymer resin).

[dzhuo]

Did you really end up not having to wash the media before using it in a reactor?

[HighlandReefer]

Thanks for your input Randy.

The articles I have been readings all reference to use the HAIX at around a pH of 7.1-7.5. I'm not sure why or if they are effective at normal reef pH.

[Randy Holmes-Farley]

The biggest problem with organic polymers to bind phosphate in seawater is the huge competition for binding sites from chloride and sulfate coupled with a relatively poor affinity for phosphate.

[HighlandReefer]

With this information, I am having problems understanding how using a polymer for encapsulating ferric oxide can improve performance for removing phosphate in our reef tank. I can find no studies specific to phosphate. It seems that these polymers are more used for removing arsenic with some mention of strontium.

[Acrotrdco]

Originally Posted by dzhuo

Did you really end up not having to wash the media before using it in a reactor?

Well I did rinse it with RO/DI water once, that's it. If I were using Rowaphos / GFO I'd have to rinse it at least half a dozen times before I could use them in my sump.

Originally Posted by 2thdeekay

What size are the beads? Are they uniformly round? Thanks!

About half the size of caviar, or if you know what's the size of masago (if you like sushi), that's about the same size.

Read here:
http://en.wikipedia.org/wiki/Tobiko

[2thdeekay]

Originally Posted by Acrotrdco

About half the size of caviar, or if you know what's the size of masago (if you like sushi), that's about the same size.
Read here:
http://en.wikipedia.org/wiki/Tobiko

Thanks Acro! Helpful details always nice. Masago/tobiko is a family favorite.

[Acrotrdco]

Randy,

Answering your question regarding whether PO4x4 would not leak iron ion into the water column, one of our local reefer QQ had perform the tests:

He took sample from 3 different sources, from left to right: Rowaphos, common GFO, PO4x4


then soak it in distilled water, wait for 24 hours then measure the iron concentration in the distilled water.

Sample size (the small red cap is about 3.6ml volume, weights 1.68g) -
Rowaphos: 3.19g (0.87 g/ml)


Common GFO - 2.22g (0.62g / ml)


PO4x4 - 2.50g (0.69g / ml)


After mixing with distilled water, you can see the cloudiness of the samples:


24 hours later



As you can see, the Rowaphos sample is still pretty cloudy, and the particle still haven't settle yet, in order to speed this up, the sample is being filtered with a filter paper, but the result isn't that great:

After filtering:


Another 24 hours later
From left to right: new Rowaphas sample rinsed thoroughly with RO/DI water, original Rowaphas sample filtered, GFO sample filtered, PO4x4 sample filtered.


Using Hanna HI 721 colorimeter:

[Acrotrdco]

Here're the results:

Original Rowaphos sample filtered:


New Rowaphos sample rinsed with RO/DI thoroughly


As you can see, the difference between the two samples are pretty obvious:


Common GFO sample:


PO4x4 sample:


So I think their claim of not leaking iron ion into water column is actually... true!

[2thdeekay]

Yes, nobody denied GFO leaches iron ions, it's a moot point.

Originally Posted by Randy Holmes-Farley

I do not doubt that GFO releases soluble iron. I also do not consider that a problem. I add iron to my system.

@ ocean pH, Fe ions don't stay in solution well, and get utilized by organisms fairly quickly. At the ocean's surface, Fe is very low, @ ~0.000006 ppm. So, to imply that there is a problem with leaking iron ions equivalent to 10x the concentration of seawater is most likely pointless.

Are those extra iron ions harmful, or beneficial to your system? That's the real question!

Iron in a Reef Tank
http://www.advancedaquarist.com/issues/aug2002/chem.htm

Iron: A Look At Organisms Other Than Macroalgae
http://www.advancedaquarist.com/2002/10/chemistry

[Randy Holmes-Farley]

I think there are some potential issues here, not least of which is that the test you are using may well detect particulates as soluble iron. The same way a calcium kit will. They may all have the same levels of soluble iron, just different levels of particulates.

That said...

So I think their claim of not leaking iron ion into water column is actually... true!

True? What value does the meter read on the starting DI water? 0.05 ppm is a LOT of iron! I realize that you used a lot of GFO in a small amount of water, but bear in mind that the NSW level of iron is on the order of 0.000006 ppm, so even accounting for dilution effects, that is a lot if real and accurate.

[dzhuo]

Thx for doing this Acrotrdco! The test is very informative. It's very surprise to see how clean PO4x4 is which is really what I am mostly interested about; rinsing GFO media is not fun at all.

Other than the iron leaching aspect of PO4x4, how are your general impression with this product so far? Have you seen your phosphate drop?

[Acrotrdco]

er.. ok let me rephase myself better.

Rowaphos, common GFO and PO4x4 all leaks iron ion into the water column, but PO4x4 leaks less, comparing to the others.

Cool?

Originally Posted by dzhuo

Thx for doing this Acrotrdco! The test is very informative. It's very surprise to see how clean PO4x4 is which is really what I am mostly interested about; rinsing GFO media is not fun at all.

Other than the iron leaching aspect of PO4x4, how are your general impression with this product so far? Have you seen your phosphate drop?

My PO4 was at 0.015 level before using PO4x4 (I was using Rowaphos), and after switching to 50ml of PO4x4, I have not measured any change in my PO4, and I've been feeding quite heavily lately since I've introduced a few new fishes to my tank, trying to make them to start feeding on frozen food.

[Randy Holmes-Farley]

Well, yes and no. We need to be very careful what we conclude.

Release of particles, no matter how small, does not imply any availability of the iron for uptake into organisms (like microalgae or corals), or availability to function as a catalyst for precipitation of CaCO3. It may simply be solids that will settle out in the tank like fine sand.


For many purposes, it is the true soluble iron that is the concern. To separate out the solids, one could probably centrifuge them out, or remove them by ultrafiltration as through a dialysis membrane.

So to that extent, I'm not sure one can make a conclusion about the differences, if any, in such an experiment, except that there is the potenntial for more total iron to get into the system from the uncoated ones.

To expand a bit why I'm concerned, the methods used in such an iron test will usually involve binding the iron to a dye. Strongly binding it so one can be sure that all available iron is bound. Under these circumstances, iron may be dissolved off of particles and appear as soluble iron when in reality, it was originally present as a particle.

The same sort of thing is well known to happen in calcium and alkalinity tests, where solids dissolve during the testing, but which do not reflect real available calcium or alkalinity in the water.