is lignite better at everything ?

[TwoPartSolution]

So I have been doing a lot of reading on carbon. From the start it was apparent that lignite is a better carbon choice than bituminous for our industry because it's macroporous structure is more effective at removing color pigments.

However there are a handful of other reasons why aquarists use carbon including removing medications and contaminants. I have read article after article and have not really found what pore size is more effective at removing these items or what size some of the more common medications and contaminates are. More to the point is the macroporous structure found in the lignite more effective at removing medications and contaminants than the microporous structure found in bituminous carbon?

Thanks , Ryan

 

[Boomer]

Yes Ryan and you are correct. Think of it this way. GAC is like a tennis net. Tennis balls, bowling balls, baseballs, etc. do not get through it, thus clog the outer surface and many of the pores. If we make the net size smaller then ping-pong balls and even marbles plug the net. We do not want them to do that. We want all of these to make it through the net and get trapped inside or more inside the GAC where there are blind channels and dead-ends that will trap them. This is why there are certain parameters to look at when looking at GAC's like Iodine #, Molasses # and Methylene Blue #. These numbers relate to pore size and or molecule size. Most GAC's do not give all 3 of these numbers, as it is part of their game, i.e., to make you think for example that a high Iodine # is s good thing. It is if you are trying to remove very, very small molecules but for large molecule removal it is a bad thing. They all work and do their job. It is a degree of efficiency. For us, Lignite is the most efficient or Peat. Wood GAC has way to big a pore structure for us and Coconut is about the worst, due to its very tiny pore structure.

This pore size opening, by entrapment, is just one of the parameters that controls the removal of molecules but there is also hydrophobic action, a chemical removal. This too is a function of pore size. The selection of GAC is based on application and for us it is Lignite, peat or Bitum. The only real reason behind bitum being more common is that it is more " user friendly", it is harder, has less or produces less dust initially.

I have posted lots here on GAC and on our chem forum on RC I have posted a ton of it. There is actully a very technical text book out on GAC.

Activated Carbon by Harry Marsh. I have a copy

 

[TwoPartSolution]

OK so the larger pores can not only capture the larger items like color pigments but also capture the smaller items? The only downside to the larger pores is it brings down the total surface area and therefore the iodine number (which is not that important to us).

So the main benefit of the ROX 0.8 is the ability to maintain the large amount of macropores and micropores/surface area at the same time. Well that and the hardness qualities that extruded carbons have. Any other benefits an extruded peat might have ?

Thanks again,

 

[Boomer]

Yes, ROX 0.8 is about the best there is and my favorite. Warner Marine is now selling it Extruded should have better flow dynamics also.