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Synthesis of CuWO4/Bi2S3 Z-scheme heterojunction with enhanced cephalexin photodegradation
Journal of Photochemistry and Photobiology A: Chemistry ( IF 4.3 ) Pub Date : 2020-03-05 , DOI: 10.1016/j.jphotochem.2020.112463
Najmeh Askari , Masoud Beheshti , Dariush Mowla , Mehrdad Farhadian

Herein, a new visible-light driven CuWO4/Bi2S3 Z-scheme composite was synthesized by a hydrothermal method. The photocatalyst was specified by XRD, FT-IR, EDX, SEM, TEM, HRTEM, BET, UV–vis DRS and PL analyses. The prepared heterojunction greatly improved the CFX photodegradation performance compared with pristine Bi2S3 and CuWO4 under LED illumination. The enhanced degradation efficiency was assigned to the higher visible-light adsorption spectrum, higher redox ability, effective separation and reduced recombination of photoinduced electron-hole pairs due to the Z-scheme construction. The point of zero charge (pzc) pH for the binary CuWO4/Bi2S3 heterojunction was calculated as 6.2 through pH drift method. The maximum degradation efficiencies in batch (76 %) and continoues flow (81.7 %) reactor were achieved at optimum values of the operating parameters as follows: irridation time = 150 min, CFX concentration = 10 ppm, pH = 3 and 0.8 g/L of catalyst dose. The optimum values for temperature and light intensity were 25 °C and 400 W/m2, respectively. According to the kinetic studies, the photocatalytic degradation of CFX followed the first order kinetic. The new Z-scheme composite indicated desirable reusability and chemical stability after five cycles. According to the trapping tests, the Z-schematic construction was proposed for the photocatalytic mechanism and superoxide and hydroxyl radicals were found to be the main active species in the degradation process. This work recommended a novel Z-scheme heterojunction as a new idea for CFX removal.



中文翻译:

头孢氨苄光降解作用增强的CuWO 4 / Bi 2 S 3 Z-方案异质结的合成

在此,通过水热法合成了新型的可见光驱动的CuWO 4 / Bi 2 S 3 Z-方案。通过XRD,FT-IR,EDX,SEM,TEM,HRTEM,BET,UV-vis DRS和PL分析指定了光催化剂。与原始Bi 2 S 3和CuWO 4相比,所制备的异质结在LED照明下大大提高了CFX的光降解性能。降解效率的提高被归因于更高的可见光吸收光谱,更高的氧化还原能力,有效的分离以及归因于Z方案结构的光诱导电子-空穴对的重组减少。二元CuWO 4 / Bi 2的零电荷(pzc)pH点通过pH漂移法计算出S 3异质结为6.2。在最佳运行参数值下,分批反应器(76%)和连续流量反应器(81.7%)的最大降解效率如下:冲洗时间= 150分钟,CFX浓度= 10 ppm,pH = 3和0.8 g / L催化剂剂量。温度和光强度的最佳值为25°C和400 W / m 2, 分别。根据动力学研究,CFX的光催化降解遵循一级动力学。新的Z型复合材料在五个循环后显示出理想的可重用性和化学稳定性。根据俘获试验,提出了Z-结构的光催化机理,发现超氧化物和羟基自由基是降解过程中的主要活性物质。这项工作推荐了一种新颖的Z型异质结作为CFX去除的新思路。

更新日期:2020-03-05
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