Degradation of methyl t-butyl ether (MTBE) by photochemical process in nanocrystalline TiO2 slurry: Mechanism, by-products and carbonate ion effect

Abstract

Methyl tert-butyl ether (MTBE) was removed from aqueous solution by photochemical reaction catalyzed by nanocrystalline TiO2 and UV radiation as a treatment strategy. The experiments were conducted at high concentration of MTBE (10,570μL−1) in a recirculating batch reactor. The optimum loading of TiO2 was found experimentally. The concentrations of MTBE and its by products were measured using a purge-and-trap gas chromatography and ion chromatography methods. Additionally, in order to explore the degradation mechanism of MTBE, by-products of MTBE oxidation were identified by using a Head space gas chromatograph–mass spectrometer (HS/GC/MS) as tert-butyl formate (TBF), tert-butyl alcohol (TBA), acetone, 2-methyl-1-propene and isopropanoic acid, all are readily degraded photocatalytically. Nearly complete removal of MTBE (>99.9%) was achieved after 2h of reaction and a pseudo first order rate constant for the degradation of MTBE was estimated to be 6.4×10−2min−1. Moreover TBF degradation rate was slower and proceeded with a first-order rate constant of 2.8×10−2min−1. Finally, the percent of photocatalytic degradation of MTBE was studied in the presence of carbonate ion. Mass balance calculations have shown that MTBE is virtually completely mineralized. This study offers a potential remediation technique for treating MTBE-contaminated groundwater.