MOE Key Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, PR China.
MOE Laboratory of Groundwater Circulation and Evolution, School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China.
Sci Total Environ. 2020 Nov 1;741:140192. doi: 10.1016/j.scitotenv.2020.140192. Epub 2020 Jun 16.
A novel direct Z-scheme NiGaO/CeO nanocomposite was designed and prepared via simple sol-hydrothermal and calcination methods, and its sonocatalytic activity was tested by studying the degradation of a model antimicrobial agent, malachite green (MG), under ultrasonic irradiation. Near complete (96.2%) degradation of MG (at 10 mg/L) could be achieved by the NiGaO/CeO nanocomposite (at 1.0 g/L) after ultrasonic irradiation (40 kHz, 300 W) for 60 min at 25 °C. Under the same conditions, only 51.2 and 72.0% of the MG degraded in the presence of NiGaO and CeO (at 1.0 g/L), respectively. These results demonstrate that the direct Z-scheme NiGaO/CeO nanocomposite has excellent sonocatalytic activity, which is attributed to the matching band-gaps between NiGaO and CeO. The sonocatalytic activity of NiGaO/CeO nanocomposite decreased by 17% after four cycles of reuse, which is indicative of relatively good reusability. Scavenging experiments revealed that sonocatalytic degradation of MG results from the combined action of hydroxyl radicals (OH) and holes (h), with the latter having a greater contribution. The pathways and mechanism of MG degradation were proposed based on the degradation intermediates detected. The results demonstrate that the prepared direct Z-scheme NiGaO/CeO nanocomposite worked as designed and exhibited high and stable sonocatalytic activity during MG degradation, and could thus serve as a promising candidate in sonocatalytic treatment of other organic pollutants in wastewaters. The findings also provide new insights on the mechanism of sonocatalytic degradation and the design of efficient Z-scheme sonocatalysts.
一种新型的直接 Z 型 NiGaO/CeO 纳米复合材料通过简单的溶胶-水热和煅烧方法设计和制备，并通过研究超声辐射下模型抗菌剂孔雀石绿 (MG) 的降解来测试其声催化活性。在 25°C 下，超声辐射（40 kHz，300 W）60 min 后，NiGaO/CeO 纳米复合材料（1.0 g/L）可实现 MG（10 mg/L）近完全（96.2%）降解。在相同条件下，NiGaO 和 CeO（1.0 g/L）存在时，MG 的降解率分别仅为 51.2%和 72.0%。这些结果表明，直接 Z 型 NiGaO/CeO 纳米复合材料具有优异的声催化活性，这归因于 NiGaO 和 CeO 之间匹配的带隙。NiGaO/CeO 纳米复合材料在重复使用四次后，其声催化活性降低了 17%，表明其具有较好的可重复使用性。清除实验表明，MG 的声催化降解是由羟基自由基 (OH) 和空穴 (h) 的协同作用引起的，后者的贡献更大。根据检测到的降解中间产物提出了 MG 降解的途径和机制。结果表明，所制备的直接 Z 型 NiGaO/CeO 纳米复合材料按设计工作，在 MG 降解过程中表现出高且稳定的声催化活性，因此可作为废水处理其他有机污染物的有前途的声催化剂候选物。研究结果还为声催化降解机制和高效 Z 型声催化剂的设计提供了新的见解。
