Homogeneous-phase Degradation of Bromacil in Water Using Concentrated Sunlight and Organic-Dye Photocatalyst

摘要

The present investigation was undertaken to determine conditions for the photochemical destruction of organic contaminants in water by means of concentrated solar irradiation, using dissolved organic dye catalysts. Several investigators have reported accelerated oxidation of organic materials dissolved in water by use of solar radiation in the presence of organic dye catalysts such as methylene blue, singlet oxygen being the active oxidant. The WIS solar furnace was the principal test site, providing a range of solar flux up to about 5000 kW/m~2-onto a quartz tube reactor. The furnace consists of a flat heliostat (100 m~2) with twoaxis tracking of the sun, mounted outdoors, that reflects to a spherical mirror made of 600 curved mirror facets located in a building. This 2-stage optical system produces a solar image approximately 5 cm in diameter in the focal plane. The range of solar flux is achieved by opening the door of the building, acting as a shutter. The receiver consists of a quartz tube 1 cm OD (0.8 cm ID), 7 cm long positioned at the focus of the furnace backed up by a 2-dimensional CPC. The CPC is water-cooled. Supporting solar irradiations were carried out under static conditions using heliostats of the WIS solar tower, and also with normal sunlight. Bromacil was tested extensively as a model compound. Attempts were made to correlate the rate of bromacil disappearance with process variables. The bulk of the chemical analysis was conducted using spectrophotometry and high pressure liquid chromatography (HPLC).