Enhanced degradation of organic pollutant by bimetallic catalysts decorated micromotor in advanced oxidation processes

A novel buoyant force-propelled micromotor is designed by decorating bimetallic catalysts (Ag and Pt NPs) on glassy carbon bead matrix for high efficient removal of organic pollutant via advanced oxidation processes. The micromotor floats to the top of solution when enough number of bubbles are accumulated on its surface and then sinks to the bottom after the evolution of bubbles. Owing to the excellent catalytic effect of Ag and Pt NPs, oxygen bubble generation and evolution frequencies are improved, leading to the ultra-fast movement of micromotor in H2O2 solution with a long lifetime of 6 h and a highest speed of ca. 12 mm/s. Meanwhile, active radical species are produced in the reaction of Ag NPs and H2O2. As a result, the synergy effect of vigorous intermixing and peroxidase mimics activity of Ag NPs speeds up the degradation significantly. In order to improve the decontamination efficiency, key factors that affect the motion performance and the generation of ROS, including H2O2, sodium dodecyl sulfate, buffer solution and the amount of micromotors, are discussed using response surface methodology. Taking methylene blue (MB) as pollutant model, the degradation rate increased from 32.47% to 90.42% after the deposition of Pt NPs on Ag micromotor, indicating the excellent catalytic effect of the bimetallic catalysts modified micromotor. Possible degradation pathway of MB was proposed, based on the results of quantum chemistry calculation and LC/MS analysis. Overall, the ultra-high traveling speed and the excellent catalytic effect make it to be a promise candidate for environmental remediation.