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  • 學位論文

製備g-C3N4/Bi2O2CO3複合光催化劑降解染料之研究

Application of g-C3N4/Bi2O2CO3 layered composite photocatalyst in dye degradation

指導教授 : 王雅玢 游勝傑

摘要


現在雖TiO2被廣泛的應用,但因為快速的重組及有限的可見光吸收造成低量子效率,並且含量逐漸減少,現今嘗試找尋新的光催化劑能克服這些問題。本研究製備g-C3N4與Bi2O2CO3合成g-C3N4/Bi2O2CO3複合光催化劑,來提升光吸收的效果及減少電子-電洞的重組,進而提升光催化的效率。 本研究以尿素在不同煅燒溫度、方式、時間下製備成g-C3N4,Bi(NO3).5H2O及Na2CO3以複分解方式製備成Bi2O2CO3, 並依重量比例用兩種不同方法合成g-C3N4/Bi2O2CO3光催化劑,在25ppm濃度下之活性黑染料 (RB5)進行吸附及降解測試,找尋最佳的合成材料及比例,並觀察此光催化劑與反應溫度及光強度對光催化之效果,探討不同製備條件及環境條件對光催化劑的影響。 在25ppm RB5的去除測試中,Bi2O2CO3有很好的吸附效果可達64.48%, g-C3N4的吸附效果較低但降解效果優於Bi2O2CO3,總去除率皆可達59.77%。一段式或二段式煅燒兩種方式所製備的g-C3N4晶體差異並不明顯,而二段式煅燒的吸附效果皆優於一段式的煅燒,以總去除量來看,在二段式煅燒的兩小時是有最好的去除效果,可以達到55.33%之去除率、27.66mg/g之去除量。直接複合光催化劑中,二段式煅燒的吸附效果皆優於一段式的煅燒,不論是一段式或二段式煅燒,直接複合的吸附效果皆優於混合合成。C/B-2/2合成比例在1:3時可以達到最好的吸附及降解效果,總去除率為60%。在高溫的環境下,水中溶氧會下降,而會抑制光催化反應中電子-電洞還原氧的能力,而使超氧自由基減少,影響光催化效果。光子越多,單位時間和面積所激發出來的電子也多,電子-電洞也就多,氧化能力也就增強,因此光強度對光催化非常關鍵,強度大於140Lux時,催化反應的效果會有明顯的增加。本研究之複合光催化劑,可有效使用可見光進行染料的脫色而是TiO2無法達到的效果。

並列摘要


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.

並列關鍵字

photocatalysis degradation g-C3N4/Bi2O2CO3 RB5

參考文獻


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