Three-dimensional hierarchical Aa/Mg(Ni)Al-layered double hydroxide Janus micromotor derived from lotus pollen for active removal of organic pollutant

摘要

Micromotors have gained considerable attention in the field of environmental remediation owing to their self-propulsion motion that can efficiently accelerate the mass transfer and mixing in solution. Herein, we reported a novel Ag/Mg(Ni)Al-layered double hydroxide (LDH) Janus micromotor derived from lotus pollen for dynamic removal of organic pollutant from water. The as-prepared three-dimensional (3D) flower-sphere micromotor was composed of freestanding Mg(Ni)Al-LDH nanosheets half-deposited with Ag nanoparticles. Under the recoil force caused by the oxygen bubbles those were generated via the decomposition of H2O2 catalyzed by Ag nanoparticles, Ag/Mg(Ni)Al-LDHs micromotors could move rapidly with a speed of 115.4 +/- 10.3 mu m s(-1) (approximate to 2.2 body lengths s(-1)) in 5 wt H2O2. Furthermore, the maximum Congo red (CR) adsorption capacity of Ag/MgAl-LDH micromotor was up to 350.16 mg g(-1), which was 1.33 times greater than the MgAl-LDHs (non-micromotor). Meanwhile, the adsorption rate was significantly accelerated compared to the non-micromotor counterparts. The results show that the enhanced adsorption capacity of micromotor benefited from the combination of 3D porous microstructure with high surface area (209.7 m(2) g(-1)), electrostatic attraction and self-propelled movement.