Removing TCE

Ask an Expert From: Products Finishing,

Posted on: 10/1/2003

Question: I saw your article on the web about TCE.

Question:

I saw your article on the web about TCE. I live in Woburn MA, home of the film "A Civil Action." I have been using a water distiller to rid my water of impurities. Reading your article, I now realize that since the boiling point is 165 F, below 212 F of water, I am not removing the TCE. Can you confirm that? Can you suggest any other method of removal, such as filtering? J.A.

Answer:

The boiling point of 1,1,1-trichloroethane is 165F. The solvent you reference in your question is thrichloroethylene (TCE) which has a boiling point of 189F. Both solvents have boiling points below that of water (212F). Since I am not familiar with your water distiller, it is difficult for me to comment on its effectiveness.

Simply boiling the water on your stove can boil away excess solvent, but in reality, this would only be effective for gross removal. The very low levels that could be in groundwater may not be able to be removed with distillation apparatus. If you have a full distillation column where you boil a liquid (in this case the water) and send the gas (steam) through a condenser and collect the condensate in another container, you also will not be effective at removing the solvent.

Almost everything will come over to the collection container. The first to come across would be any azeotropes of TCE and water that may have formed. An azeotrope is a constant boiling mixture of two or more components, in this case TCE and water. At a ratio of about 95% TCE and 5% water, an azeotrope will form that has a boiling point of 164F. Next any “free” solvent will come over at about 189F and finally the water will boil and come over at 212F.

Now armed with these facts, it still may not be possible to physically separate the two, since TCE is soluble in water to a very limited extent. I believe treatment of water with activated charcoal filters may be the best method of removing any type of solvent impurity from water. I would first contact your local water treatment/regulation department and find out the status of the drinking water.

 



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