Controllable synthesis of amidoximated self-propelled tubular micromotors for enhanced uranium recovery: non-invasive mixing and on-the-move capturing

Abstract

Micro-/nanomotors that combine attributes of autonomous movement and adsorption performance are attractive for efficient pollutant treatment. However, micro/nanomotors design still suffers from challenges including complex manufacturing processes, specific instrument demands and low yields. Herein, we proposed amidoxime-functionalized polydopamine tubular micromotors (DNBMs-AO) and demonstrated their application for rapid selective adsorption of uranium from contaminated seawater. The whole fabrication procedure is simplified and straightforward by curcumin templating and in-situ reduction/graft method. The manganese dioxide (MnO2) catalyst and amidoxime groups are subsequently anchored on the outer and inner side of nanotube surface. Besides, the distribution and amount of modified MnO2 and amidoxime groups can be manipulated via directly changing the reduction time. DNBMs-AO are driven and propelled by microbubbles produced by MnO2-triggered catalytic decomposition of hydrogen peroxide, which can reach high velocity at 302.6 μm s−1. The static adsorption results indicate that the adsorption of U(VI) onto DNBMs-AO can be better described by Langmuir model with the maximum adsorption capacity of 313.9 mg/g. Moreover, the motion of DNBMs-AO can efficiently improve the U(VI) diffusion under low H2O2 concentration, and enhance the adsorption kinetics to approximately 2.5 times. DNBMs-AO also exhibits high selectivity towards U(VI) and excellent performance stability, endowing its potential application in environmental engineering field.