New method for removal of MTBE from water

MTBE, (methyl tertiary butyl ether) is a chemical compound added to gasoline as an ‘oxygenator’ to make it burn cleaner and reduce air pollutants. The US EPA recently announced it would begin phasing out the use of MTBE in gasoline. The move follows the California Air Resources Board’s (CARB) decision last year to approve laws banning the additive from the beginning of 2003 (see related story).

“It has a very distinctive odor, and it is detectable at extremely low levels,” says Reynaldo Barreto, an associate professor of chemistry at Purdue University. “If I were to dilute an ounce of MTBE into a ton of water, you would be able to smell the MTBE.”

None of the conventional methods for removing pollutants from ground water will work effectively for MTBE. Although it is unclear whether the compound poses serious health dangers in the concentrations found in groundwater, contamination has become a concern to communities across the US.

Barreto’s technique for removing MTBE involves exposing tainted water to high-energy UV light, which eventually turns the compound into carbon dioxide. To make the reaction possible, oxygen is bubbled into the water and the common catalyst titanium dioxide is added to the water.

Bareto reckons he can eliminate the bulk of the MTBE after a couple of hours. The technique has never been tried in a commercially viable way, Bareto says because engineers think it takes too long, But, says Bareto, “It’s faster than what we have now, which is nothing.”

Now Bareto is focussing on the technique’s use in removing two possible MTBE replacement compounds from water. Those possible alternatives to MTBE are ethyl tertiary butyl ether (ETBE) and tertiary amyl methyl ether (TAME).

Data indicate that Bareto’s technique is slightly less effective in removing the two possible alternatives from water than it is in removing MTBE from water. Bareto is currently working to prove that the method also turns ETBE and TAME into carbon dioxide.