新型復(fù)合光催化劑可見光催化處理含鉻有機廢水的研究
發(fā)布時間：2019-05-21 19:40
【摘要】：光催化技術(shù)是一種綠色水處理技術(shù),其在礦化去除難降解有機物的同時,能夠還原回收重金屬,光催化技術(shù)的核心在于研發(fā)高可見光響應(yīng)的光催化材料,提高對太陽光的利用率。本文采用刻蝕-沉淀法制備了 CsPMo/Bi203復(fù)合光催化劑。結(jié)果表明α-Bi_2O_3與CsPMo復(fù)合后形成異質(zhì)結(jié),帶來了光電流的提高和光生電子轉(zhuǎn)移速率的加快。進一步,以苯酚為主要污染物,考察了 CsPMo/Bi_2O_3的光催化性能。結(jié)果發(fā)現(xiàn),在相同可見光的照射下,CsPMo/Bi_2O_3降解苯酚的速率約為Bi_2O_3的2.68倍。機理研究表明,CsPMo/Bi_2O_3光催化降解苯酚過程中,超氧自由基(O2·-)起主要作用,羥基自由基(·OH)、空穴(h+)起輔助作用。在此基礎(chǔ)上,采用刻蝕-沉淀法,通過構(gòu)造α-Bi_2O_3、BiOI、AgI多異質(zhì)結(jié),制備了光催化劑AgI/BiOI-Bi_2O_3,并使用多種表征手段對催化劑的結(jié)構(gòu)、光的吸收、電化學(xué)性質(zhì)等進行表征。結(jié)果發(fā)現(xiàn),相比于Bi_2O_3,AgI/BiOI-Bi_2O_3展現(xiàn)出:光電流提升、帶隙減小、電子傳輸阻抗減小、平帶電勢負移,最終帶來了在異質(zhì)結(jié)界面電子產(chǎn)生的增加、光生電子和空穴分離的加快。然后以Cr(Ⅵ)及含鉻有機廢水為研究對象,考察了AgI/BiOI-Bi_2O_3還原Cr(Ⅵ)的性能,發(fā)現(xiàn)其在可見光下、實際廢水的pH條件下展現(xiàn)出優(yōu)異的光催化活性。當(dāng)制備條件為KI:Bi_2O_3=1:1、AgNO3:Bi_2O_3=1:10 時,制備的 AgI/BiOI-Bi_2O_3 活性最高。最佳的 AgI/BiOI-Bi_2O_3對Cr(Ⅵ)的還原速率約為Bi_2O_3的16倍。多次循環(huán)使用,催化劑依然有很好的活性,說明本催化劑能夠很好地適用于含鉻廢水的處理。進一步,采用刻蝕-沉淀法和煅燒結(jié)合,通過構(gòu)造AgI、β-B12O3、Bi_2O_2CO_3 多異質(zhì)結(jié),制備 AgI/β-Bi_2O_3-Bi_2O_2CO_3,采用 XRD、FT-IR 對結(jié)構(gòu)表征,SEM對形貌表征,XPS對表面譜學(xué)表征,UV-Vis-DRS研究其吸收光譜。結(jié)果表明:(1)AgI、β-Bi_2O_3、Bi_2O_2CO_3很好復(fù)合在一起;(2)煅燒溫度對制備AgI/β-Bi_2O_3-Bi_2O_2CO_3有很大的影響,呈現(xiàn)出顯著的性能差異,325℃為最佳煅燒溫度;(3)AgI/β-Bi_2O_3-Bi_2O_2CO_3可見光吸收顯著增加。以Cr(Ⅵ)-苯酚廢水為研究對象,考察了催化劑的可見光催化性能,發(fā)現(xiàn)其對實現(xiàn)Cr(Ⅵ)與苯酚同步消減有很好的效果。
[Abstract]:Photocatalytic technology is a kind of green water treatment technology, which can reduce and recover heavy metals while mineralization and removal of refractory organic matter. The core of photocatalytic technology lies in the development of photocatalysis materials with high visible light response. Improve the utilization of sunlight. In this paper, CsPMo/Bi203 composite photocatalyst was prepared by etch-precipitation method. The results show that the heterogeneous junction is formed after the combination of 偽-Bi_2O_3 and CsPMo, which leads to the increase of photocurrent and the acceleration of photogenerated electron transfer rate. Furthermore, the photocatalytic performance of CsPMo/Bi_2O_3 was investigated with phenol as the main pollutant. The results showed that the degradation rate of phenol by CsPMo/Bi_2O_3 was about 2.68 times higher than that by Bi_2O_3 under the same visible light irradiation. The mechanism studies show that the oxidative radical (O2 -) plays a major role in the photocatalytic degradation of phenol by CsPMo/Bi_2O_3, and the hydroxyl radical (OH), hole (h) plays an auxiliary role. On this basis, the photocatalyst AgI/BiOI-Bi_2O_3, was prepared by etch-precipitation method by constructing 偽-Bi_2O_3,BiOI,AgI multi-Heterojunction, and the structure and light absorption of the catalyst were characterized by various characterization methods. Electrochemical properties were characterized. The results show that compared with Bi_2O_3,AgI/BiOI-Bi_2O_3, the photocurrent increases, the band gap decreases, the electron transmission impedance decreases, and the flat band potential moves negatively, which finally leads to the increase of electron generation at the interface of heterojunction. The separation of photogenerated electrons and holes is accelerated. Then, taking Cr (VI) and chromium-containing organic wastewater as the research object, the performance of Cr (VI) reduction by AgI/BiOI-Bi_2O_3 was investigated, and it was found that AgI/BiOI-Bi_2O_3 showed excellent photocatalytic activity under the condition of pH in visible light. When the preparation conditions were KI:Bi_2O_3=1:1,AgNO3:Bi_2O_3=1:10, the activity of AgI/BiOI-Bi_2O_3 was the highest. The reduction rate of Cr (VI) by the best AgI/BiOI-Bi_2O_3 is about 16 times that of Bi_2O_3. After repeated recycling, the catalyst still has good activity, which indicates that the catalyst can be well applied to the treatment of chromium-containing wastewater. Furthermore, AgI/ 尾-Bi_2O_3-Bi_2O_2CO_3, was prepared by the combination of etch-precipitation method and calcination, and the structure of AgI/ 尾-Bi_2O_3-Bi_2O_2CO_3, was characterized by XRD,FT-IR by constructing AgI/ 尾-B12O _ 3 and Bi _ 2O _ 2O _ 2CO _ 3 hetero-junction. The morphology was characterized by SEM, the surface spectroscopy was characterized by XPS, and the absorption spectrum was studied by UV-Vis-DRS. The results show that: (1) AgI, 尾-Bi_2O_3,Bi_2O_2CO_3 is well combined; (2) calcination temperature has great influence on the preparation of AgI/ 尾-Bi_2O_3-Bi_2O_2CO_3, and the best calcination temperature is 325 鈩，
本文編號：2482339
[Abstract]:Photocatalytic technology is a kind of green water treatment technology, which can reduce and recover heavy metals while mineralization and removal of refractory organic matter. The core of photocatalytic technology lies in the development of photocatalysis materials with high visible light response. Improve the utilization of sunlight. In this paper, CsPMo/Bi203 composite photocatalyst was prepared by etch-precipitation method. The results show that the heterogeneous junction is formed after the combination of 偽-Bi_2O_3 and CsPMo, which leads to the increase of photocurrent and the acceleration of photogenerated electron transfer rate. Furthermore, the photocatalytic performance of CsPMo/Bi_2O_3 was investigated with phenol as the main pollutant. The results showed that the degradation rate of phenol by CsPMo/Bi_2O_3 was about 2.68 times higher than that by Bi_2O_3 under the same visible light irradiation. The mechanism studies show that the oxidative radical (O2 -) plays a major role in the photocatalytic degradation of phenol by CsPMo/Bi_2O_3, and the hydroxyl radical (OH), hole (h) plays an auxiliary role. On this basis, the photocatalyst AgI/BiOI-Bi_2O_3, was prepared by etch-precipitation method by constructing 偽-Bi_2O_3,BiOI,AgI multi-Heterojunction, and the structure and light absorption of the catalyst were characterized by various characterization methods. Electrochemical properties were characterized. The results show that compared with Bi_2O_3,AgI/BiOI-Bi_2O_3, the photocurrent increases, the band gap decreases, the electron transmission impedance decreases, and the flat band potential moves negatively, which finally leads to the increase of electron generation at the interface of heterojunction. The separation of photogenerated electrons and holes is accelerated. Then, taking Cr (VI) and chromium-containing organic wastewater as the research object, the performance of Cr (VI) reduction by AgI/BiOI-Bi_2O_3 was investigated, and it was found that AgI/BiOI-Bi_2O_3 showed excellent photocatalytic activity under the condition of pH in visible light. When the preparation conditions were KI:Bi_2O_3=1:1,AgNO3:Bi_2O_3=1:10, the activity of AgI/BiOI-Bi_2O_3 was the highest. The reduction rate of Cr (VI) by the best AgI/BiOI-Bi_2O_3 is about 16 times that of Bi_2O_3. After repeated recycling, the catalyst still has good activity, which indicates that the catalyst can be well applied to the treatment of chromium-containing wastewater. Furthermore, AgI/ 尾-Bi_2O_3-Bi_2O_2CO_3, was prepared by the combination of etch-precipitation method and calcination, and the structure of AgI/ 尾-Bi_2O_3-Bi_2O_2CO_3, was characterized by XRD,FT-IR by constructing AgI/ 尾-B12O _ 3 and Bi _ 2O _ 2O _ 2CO _ 3 hetero-junction. The morphology was characterized by SEM, the surface spectroscopy was characterized by XPS, and the absorption spectrum was studied by UV-Vis-DRS. The results show that: (1) AgI, 尾-Bi_2O_3,Bi_2O_2CO_3 is well combined; (2) calcination temperature has great influence on the preparation of AgI/ 尾-Bi_2O_3-Bi_2O_2CO_3, and the best calcination temperature is 325 鈩，
本文編號：2482339
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