He Xu, Bahk Yeon Kyoung, Wang Jing
Institute of Environmental Engineering, ETH Zurich, Schafmattstrasse 6, 8093, Zurich, Switzerland; Advanced Analytical Technologies Laboratory, EMPA, Überlandstrasse 129, 8600, Dübendorf, Switzerland.
Institute of Environmental Engineering, ETH Zurich, Schafmattstrasse 6, 8093, Zurich, Switzerland; Advanced Analytical Technologies Laboratory, EMPA, Überlandstrasse 129, 8600, Dübendorf, Switzerland.
Chemosphere. 2017 Oct;184:601-608. doi: 10.1016/j.chemosphere.2017.06.011. Epub 2017 Jun 6.
MnO- and Ag- based micromotors were developed recently as new types of micromotors with the advantage of low costs and have been utilized to treat environmental pollutants. However, knowledge about the effects of ambient conditions on the performance of them is still lacking. In this article, the influences of pH, electrolytes and surfactant on the treatment of organic dye (with methylene blue as the representative) by the commercial MnO and Ag micromotors with HO as the fuel were studied. In the motion visualization experiments, besides the routine types of trajectories, the circular motion of micromotors around the already formed bubbles was observed for the first time. In the pollutant removal experiments, two abatement mechanisms (catalytic degradation and adsorptive bubble separation) were studied. The decolorization efficiency for MnO due to catalytic degradation increased with the increasing pH, which disagreed with previous studies in which no HO was added. The inhibitory effects of the tested electrolytes were in the order: CaCl>NaNO>NaCl. Surfactant can increase the decolorization efficiency only under highly alkaline conditions. For Ag, decolorization only occurs with the existence of surfactant at high pH values (pH = 11.4) indicating that the dominant mechanism is adsorptive bubble separation.
基于MnO和Ag的微电机是近年来开发的新型微电机，具有成本低的优势，并已被用于处理环境污染物。然而，关于环境条件对其性能影响的知识仍然缺乏。在本文中，研究了pH值、电解质和表面活性剂对以H₂O₂为燃料的商用MnO和Ag微电机处理有机染料（以亚甲基蓝为代表）的影响。在运动可视化实验中，除了常规类型的轨迹外，首次观察到微电机围绕已形成的气泡做圆周运动。在污染物去除实验中，研究了两种减排机制（催化降解和吸附气泡分离）。由于催化降解，MnO的脱色效率随pH值的升高而增加，这与之前未添加H₂O₂的研究结果不同。测试电解质的抑制作用顺序为：CaCl₂＞NaNO₃＞NaCl。表面活性剂仅在高碱性条件下才能提高脱色效率。对于Ag，只有在高pH值（pH = 11.4）且存在表面活性剂的情况下才会发生脱色，这表明主要机制是吸附气泡分离。
