Photocatalytic degradation of atrazine using TiO(sub 2)-impregnated mesh

摘要

TiO(sub 2) photocatalysis is investigated is a potential means for the disposal of pesticide rinsate waste at agrochemical dealerships. The focus is an evaluation of parameters that affect the rate and mechanism of atrazine degradation using formulated atrazine (ca. 20-25 ppm), TiO(sub 2) mesh, a high-pressure mercury-vapor lamp, and solar irradiation. The UV transmission of a variety of transparent materials was measured and atrazine photocatalysis was carried out using several materials as reactor covers. The pseudo-first-order rate constants were calculated and compared to determine which cover results in the most efficient atrazine degradation. A clear acrylic gave results nearly identical to Pyrex and was chosen for future photocatalytic experiments. UV intensity and photocatalytic rate were studied as a function of different numbers of layers of TiO(sub 2) mesh. It was found that five layers give the optimum rate of degradation without employing excess mesh. In order to assess the general effect of impurities present in water on the rate of atrazine degradation, water from five different sources was obtained and each sample was analyzed for purity and used to prepare aqueous atrazine for photocatalytic degradation. The results show that contaminants specific to different locations are likely to inhibit the rate of photocatalysis to different degrees. While working to maximize the rate of atrazine degradation, studies are concurrently in progress to elucidate the mechanism of degradation for the experimental conditions employed herein. Initial results indicate that the overall degradation of atrazine to the reported end product, cyanuric acid, occurs by two distinct pathways of similar importance.