新型复合光催化剂可见光催化处理含铬有机废水的研究
发布时间：2019-05-21 19:40
【摘要】：光催化技术是一种绿色水处理技术,其在矿化去除难降解有机物的同时,能够还原回收重金属,光催化技术的核心在于研发高可见光响应的光催化材料,提高对太阳光的利用率。本文采用刻蚀-沉淀法制备了 CsPMo/Bi203复合光催化剂。结果表明α-Bi_2O_3与CsPMo复合后形成异质结,带来了光电流的提高和光生电子转移速率的加快。进一步,以苯酚为主要污染物,考察了 CsPMo/Bi_2O_3的光催化性能。结果发现,在相同可见光的照射下,CsPMo/Bi_2O_3降解苯酚的速率约为Bi_2O_3的2.68倍。机理研究表明,CsPMo/Bi_2O_3光催化降解苯酚过程中,超氧自由基(O2·-)起主要作用,羟基自由基(·OH)、空穴(h+)起辅助作用。在此基础上,采用刻蚀-沉淀法,通过构造α-Bi_2O_3、BiOI、AgI多异质结,制备了光催化剂AgI/BiOI-Bi_2O_3,并使用多种表征手段对催化剂的结构、光的吸收、电化学性质等进行表征。结果发现,相比于Bi_2O_3,AgI/BiOI-Bi_2O_3展现出:光电流提升、带隙减小、电子传输阻抗减小、平带电势负移,最终带来了在异质结界面电子产生的增加、光生电子和空穴分离的加快。然后以Cr(Ⅵ)及含铬有机废水为研究对象,考察了AgI/BiOI-Bi_2O_3还原Cr(Ⅵ)的性能,发现其在可见光下、实际废水的pH条件下展现出优异的光催化活性。当制备条件为KI:Bi_2O_3=1:1、AgNO3:Bi_2O_3=1:10 时,制备的 AgI/BiOI-Bi_2O_3 活性最高。最佳的 AgI/BiOI-Bi_2O_3对Cr(Ⅵ)的还原速率约为Bi_2O_3的16倍。多次循环使用,催化剂依然有很好的活性,说明本催化剂能够很好地适用于含铬废水的处理。进一步,采用刻蚀-沉淀法和煅烧结合,通过构造AgI、β-B12O3、Bi_2O_2CO_3 多异质结,制备 AgI/β-Bi_2O_3-Bi_2O_2CO_3,采用 XRD、FT-IR 对结构表征,SEM对形貌表征,XPS对表面谱学表征,UV-Vis-DRS研究其吸收光谱。结果表明:(1)AgI、β-Bi_2O_3、Bi_2O_2CO_3很好复合在一起;(2)煅烧温度对制备AgI/β-Bi_2O_3-Bi_2O_2CO_3有很大的影响,呈现出显著的性能差异,325℃为最佳煅烧温度;(3)AgI/β-Bi_2O_3-Bi_2O_2CO_3可见光吸收显著增加。以Cr(Ⅵ)-苯酚废水为研究对象,考察了催化剂的可见光催化性能,发现其对实现Cr(Ⅵ)与苯酚同步消减有很好的效果。
[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 伪-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 伪-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，
本文编号：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 伪-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 伪-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，
本文编号：2482339
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