亞甲基藍(Methylene Blue)為一種普遍的染料,能在很多物質表面產生吸附作用,常被用於光觸媒分解實驗中。多氯聯苯(PCBs)具高度穩定性、不易被生物分解且易累積於脂肪中之特性,排放至環境後將危害生物體及人體的健康。本研究以溶膠-凝膠法製備釩酸鉍並添加過渡金屬銅(Copper)與鈷(Cobalt)於系統中,以不同製備條件之BiVO4、Cu/BiVO4、Co/BiVO4改質光觸媒,其原理為添加過度金屬可提高對可見光的吸收能力及降低電子電洞對再結合率,增加觸媒之光催化能力,並進一步探討對亞甲基藍與PCBs水溶液之光解效能。 研究結果顯示摻雜Cu和Co能提高觸媒對可見光的吸收,於XRD分析結果顯示,本實驗所使用之觸媒為單斜白鎢礦相(scheelite monoclinic);SEM分析顯示觸媒的顆粒能增加其表面孔隙,使受光照射面積增多,而提高光催化效果。光降解試驗中得知,以0.3 wt%-Cu/BiVO4經鍛燒溫度600 ℃下,在自然日光照射下對亞甲基藍有最佳降解效果,經光照1小時之後降解率為75 %,光照6小時之後降解率為99 %;以上述最佳操作條件針對絕緣油之多氯聯苯進行降解,其去除率為33 %,礦化率15 %,再以離子層析儀(IC)分析生成Cl-之含量發現,隨著光照時間的增加,Cl-之產量也隨之提升;於持久性試驗的結果證實,本研究自行製備之觸媒可重覆再利用。
Methylene Blue is a common dye, and its high adsorption ability take place with the surface of lots of materials. It is used for photocatalytic decomposition experiments due to decolorization. Polychlorinated biphenyls (PCBs) have been widely used in industries that are highly stable man-made organic matters. However, PCBs are not easily biodegradable, a group of persistent organic pollutants. When PCBs released to the environment through the transportation of atmosphere, water, organisms and soil in the various environmental media they can be accumulated in organisms because of the contamination in the environment. In this study, the sol-gel method was used to prepare BiVO4 photocatalysts with transition metals Cu and Co to synthesize BiVO4, Cu/BiVO4, Co/BiVO4 photocatalysts under different experimental factors. The main goal of using transition metals is to increase the adsorption capability of visible light and suppress the recombination of photogenerated hole-electron pairs. Furthermore, the treatment of methylene blue and PCBs aqueous solution can be explored. The results showed that adding Cu and Co would effectively enhance the absorption visible light on BiVO4. The XRD analytical results showed that the crystal types of the catalysts was scheelite monoclinic in this study. The findings of SEM tests showed that the particles of BiVO4 could increase the surface hole of catalyst and increased the illumination area. The optimum operating conditions of photodegradation test results were using 0.3 wt%-Cu/BiVO4 at 600 ℃ under natural sunlight. The degradation percentages of MB was up to 75 % after 1 hour, and the degradation percentages was 99 % after 6 hours. Using the same experimental factor to degrade the PCBs, the degradation percentage and mineralization were 33 % and 15 %, respectively. The IC analysis found that with increasing illumination time, the yield of Cl- was increased. Durability experiment confirmed that self-prepared catalysts in this study can be economically benefit to environmental protection studies.
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