Application of photocatalytic process for removal of methyl tert-butyl ether from highly contaminated water
The addition of methyl tert-butyl ether (MTBE) to gasoline as an additive to replace tetraethyl lead has brought about a significant improvement in air quality (Zang and Farnood, 2005a). MTBE raises the oxygen content of gasoline thus helps reduce harmful agent of CO, NOx and ydrocarbon emissions from vehicle exhausts (Jacobs et al., 2001; Zang and Farnood, 2005b; Guillard et al., 2003). About 20 million tons (t) are used worldwide mainly for this purpose (Kolb and Puttmann, 2006). Unfortunately, this improvement also leads to a negative environmental impact. Since MTBE has high water solubility, the occurrence of fuel spills or leaks from underground storage tanks or transferring pipeline has led to the contamination of water sources. The United States Environmental Protection Agency (EPA) has classified MTBE as a suspect human carcinogen, and suggested the health limit of 20–40μg/L in drinking water (USEPA, 1997). MTBE is poorly adsorbed, chemically and biologically stable, and very soluble in water, making it very persistent in the environment. Conventional treatment including air stripping, Granular Activated Carbon (GAC) adsorption and biodegradation processes using for MTBEcontaminated groundwater have been inefficient and unsatisfactory (Zang and Farnood, 2005b; Anderson, 2000). Advanced oxidation processes (AOPs), on the other hand, provide promising treatment alternative for MTBE removal (Squillace et al., 1997).