Aquarium Carbon Use

[Carl]

I updated the Aquarium Answers article about the use of activated carbon

I added more information and improved the carbon absorption table

Activated Carbon use in Aquariums

Carl

[Carl]

I have updated the Aquarium/Pond Answers article about carbon use in aquariums

Here is a quote:
"The best Premium Activated Carbon is produced from a soft, brownish-black coal (Lignite) in which the alteration of vegetable matter which has proceeded further than in peat but not as far as in bituminous coal.
Lignite based carbon is the best choice for use in aquarium & ponds to remove organic molecules, pesticides and for color removal, due to its large pore size."

Reference:
www.aquarium-pond-answers.com/2009/10/activated-carbon.html

Carl

[Carl]

I updated the "Aquarium Answers" article about the use of activated carbon with a new picture and further information.



Resource:
www.aquarium-pond-answers.com/2009/10/activated-carbon.html


Carl

[Carl]

I've updated the "Aquarium/Pond Answers" article about the use of Activated Carbon in aquariums

www.aquarium-pond-answers.com/2009/10/activated-carbon.html

Here is an excerpt:
"The forces of attraction between the carbon and the absorbed molecules are greater the closer the molecules are in size to the pores. The best absorption takes place when the pores are just large enough to admit the molecules.
Activated carbon, when contacted with water containing organic material, will remove these compounds selectively by a combination of adsorption of the less polar molecules, absorption (filtration) of the larger particles, and partial deposition of colloidal material on the exterior surface of the activated carbon.

As well as absorption, activated carbon uses a process called Adsorption, in fact adsorption is the primary method of molecule removal by carbon, not absorption.
When a material adsorbs something, it means it attaches it by chemical attraction.

The extent of removal of soluble organics by absorption depends on the diffusion of the particle to the external surface of the carbon and diffusion within the porous adsorbent. For colloidal particles, internal diffusion is relatively unimportant because of particle size.
Organic substances that pass through the column consist of hydrophilic organic molecules (substances that are attracted to, and dissolve well within, water) and hydrophobic molecules (repulsed by water).
If the molecule is “polar” (having both a hydrophobic and hydrophilic attributes) which many organic molecules are, the hydrophobic side will be attracted (attached) to the activated carbon.

Adsorption is partially the result of forces of attraction at the surface of a particle that cause soluble organic materials to adhere to the activated carbon. The limited water solubility of many organic substances will affect AC adsorption of these molecules.

Put more simply (I hope): Polar, hydrophobic and hydrophilic interactions are important interactions necessary to understand how activated carbon adsorb the certain molecules.
A Methylene Blue dye molecule is hydrophobic and has a large affinity to the hydrophobic carbon rings of the activated carbon.
The dye prefers to interact with the carbon rather than water.
Where as non chelated metals (such as copper ions) are positively charged (hydrophilic), and the carbon is neutral and hydrophobic. Therefore, the positively charged metal ions prefer to interact with the water, which is hydrophilic. “Like dissolves Like”.

This applies to most metals from the periodic table, including calcium, magnesium, etc., and for this reason most essential minerals are not removed by activated carbon unless chelated but they can loose their positive charge due to oxidative processes of the Redox Potential, which is another reason to replenish these ESSENTIAL positive mineral ions, especially if carbon is used.

This positive/negative ionization is why DOC (organics) will also negatively affect the Aquarium/Pond Redox Balance"

Carl

[mmfed01]

This is a good write up. I've often wondered about this. I've also seen arguments over what things like Purigen and Chemi-Pure do and do not remove from water...especially planted tanks...

I keep regular carbon for emergencies but currently I use Purigen and Renew in my tanks. I play around with Chemi-pure Green too....

Mike