| Summary: | 碩士 === 中原大學 === 環境工程學系 === 105 === Nowadays, although TiO2 is widely used, because of rapid recombination and limited visible light absorption, resulting in low quantum efficiency and decreasing content, it is possible to overcome these problems by trying to find new photocatalysts.
In this study, g-C3N4 / Bi2O2CO3 composite photocatalyst was synthesized by using self-made g-C3N4 and Bi2O2CO3 to enhance the effect of light absorption and reduce the recombination of electron-electric hole. g-C3N4 was prepared by urea at different calcination temperatures, method and time. Bi(NO3) 3．5H2O and Na2CO3 were used to prepare Bi2O2CO3, and the g-C3N4 / Bi2O2CO3 composite photocatalyst was synthesized by two different methods. The adsorption and degradation test of Reactive black dye (RB5) at 25ppm concentration was carried out to find the best synthetic material and ratio, and to investigate the influence of reaction temperature and light intensity.
In the 25ppm RB5 removal test, Bi2O2CO3 has a good adsorption effect of 60%, while the adsorption of g-C3N4 is low but the degradation is better than Bi2O2CO3, the total removal is 60%. The differences is not significant in the g-C3N4 crystals prepared by the one-stage or two-stage calcination, the adsorption effect of the two-stage calcination is better than that of the one-stage calcination. In terms of total removal, the best removal effect was achieved in the two-stage calcination for two hours, and the removal rate of 55.33% and the removal of 27.66 mg / g. In the direct composite (C+B), the adsorption of the two-stage calcination is better than that of the one-stage calcination. The adsorption of the direct composite is better than that of the mixed synthesis(C/B). C/B-2/2 ratio of 1: 3 can achieve the best adsorption and degradation effect, the total removal rate of 60%. In the high temperature, the dissolved oxygen in the water will decline, it will inhibit the photocatalytic reaction of the electron - hole reduction of oxygen capacity, affecting the photocatalytic effect. The more the photon, unit time and area of electrons - holes also increase, and the oxidation capacity will be enhanced, so the light intensity is very critical to photocatalysis, with greater than 140 Lux the intensity, the catalytic reaction will have significant increase. In this study, the composite photocatalyst can effectively use the visible light for the decolorization of the dye, but not for TiO2.
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