Environmental remediation by an integrated microwave/UV illumination technique - VI. A simple modified domestic microwave oven integrating an electrodeless UV-Vis lamp to photodegrade environmental pollutants in aqueous media

A simple device is described based on a modified domestic microwave oven that incorporates an UV-Vis lamp encased in Teflon to photodegrade environmental pollutants in aqueous media. The performance of this device was examined using the photodegradation of the agrochemical pollutant 2,4-dichlorophenoxyacetic acid (2,4-D) as the test process driven by a coupled photocatalytic/microwave method in an aqueous TiO2 dispersion. The aqueous dispersion was contained in a high-pressure Teflon batch (TB) reactor that also integrated a double glass cylindrical plasma lamp (DGCPL) as the source of the UV-Vis radiation. This DGCPL lamp contained mercury gas with a minute amount of neon gas and was powered solely by microwave radiation. The coupled microwave-UV-Vis irradiation of the TB-DGCPL reactor led to an enhancement of the decomposition of the 2,4-D target substrate in the modified microwave oven relative to the photocatalytic method alone. Specifically, the rates of degradation were 2x10(-3) mM min(-1) (photocatalytic/microwave method (PD/MW)) and 1.1x10(-3) mM min(-1) (photocatalytic method (PD)) even though the light irradiance was some six-fold greater in the latter method. That is, the coupled PD/MW method was about 10 times more efficient than the PD method alone. (C) 2004 Elsevier B.V. All rights reserved.