Reef Chemistry Question of the Day #112 Skimming

[Randy Holmes-Farley]

Reef Chemistry Question of the Day #112

Which of the following is most likely to be selectively removed from seawater by skimming, in the exact chemical form described?


A. Iodide (I-)
B. Nitrate (NO3-)
C. Phosphate (PO3---)
D. A fatty acid

Good luck!




































.

 

[Up2no6ood]

Im going to go with d. Being that fatty acid is a protein.

 

[beaslbob]

+1
d fatty acid
just my wild guess tho

 

[beaslbob]

Hey
is fatty acid an exact chemical form?

 

[jeffp1]

I am going to guess Iodine.

 

[TUSI]

B-nitrate

 

[hatfielj]

Fatty acids for sure

 

[Chris L]

I'm going B,C,D....

 

[Randy Holmes-Farley]

Hey
is fatty acid an exact chemical form?

Wikipedia has a good description of fatty acids here:

Fatty acid - Wikipedia, the free encyclopedia

 

[beaslbob]

At least I learned how they make margine

 

[fuzzone99]

Greetings Randy. Love this forum! Thanks for your participation. R2R Rocks!

D. Fatty Acid
Most likely due to the relative polarity of the molecule. The hydrophilic (water loving) and hydrophobic (water hating) ends seeking orientation at the water/air interface.

BTW:...I think most of us on here must be hydrophilic??

 

[Randy Holmes-Farley]

BTW:...I think most of us on here must be hydrophilic??

Yes, unless you have rabies.

 

[Rybren]

I'd have to go with "D" as well. In Randy's latest article on Phosphates, he states:
"Skimmers generally remove organic compounds, and leave behind inorganic compounds such as inorganic orthophosphate."

I believe that answers A, B, and C are all inorganic compounds while D is organic.

 

[tonizzy22]

Answer is d

 

[firstlight10]

D...

 

[ramraider]

D is this why my skimmer goes into overdrive when i dose ammino acids

 

[Randy Holmes-Farley]

D is this why my skimmer goes into overdrive when i dose ammino acids

Amino acids and fatty acids are different types of chemicals, but some fatty acids can act as surfactants and cause more foam formation. Phenylalanine and leucine, for example, will act as surfactants and lower the surface tension of water.

That said, there might be other ingredients in that supplement which has that effect as well.

 

[Randy Holmes-Farley]

And the answer is...D. A fatty acid

A fatty acid has a hydrophobic tail and a very hydrophilic head end (the carboxylic acid). With that configuration, it very much wants to align itself at an air water interface, with the tail facing the air and the head in the water. Once it binds to the air water interface, and enters a skimmer, it is readily skimmed out.

All of the other choices involve inorganic compounds that are entirely hydrophilic and will not absorb onto an air water interface, so will not be skimmed out (at least not in the exact forms shown; related chemical forms (such as organophosphates), or those ions themselves bound to organics may be skimmed out, but these are not big effects for the ions mentioned anyway).

Happy Reefing!