Efficient On-the-move Separation of Polycyclic Aromatic Hydrocarbons from Soil by MXene-derived Micromotors

Limited mass transfer in heterogeneous environments has posed a great challenge to the removal of environmentally persistent polycyclic aromatic hydrocarbons (PAHs) from soil. This work presents Mxene-derived TiO 2 /MnO 2 /MnFe 2 O 4 -βCD (TMMF-βCD) micromotors capable of self-propulsion for efficient on-the-move soil purification. A thermal annealing process was used to convert Ti 3 C 2 T x MXene into multilayer TiO 2 , followed by in-situ growth of MnO 2 , exfoliation, and functionalization with magnetic MnFe 2 O 4 and βCD-SH. Coupling self-propulsion and host-guest complexation effect induced by the βCD-SH modification, the micromotors can efficiently trap PAHs on their surface. The kinetic process of soil decontamination monitored by in-situ electrochemical impedance spectroscopy (in-situ EIS) and distribution of relaxation times (DRT) unveiled the effective migration of micromotors in the heterogenous environment and the dynamic capture of PAHs by the propelled micromotors. The phenanthrene (PHE) removal efficiency of propelled micromotors was more than 4.77 and 38.78 times that of static micromotors and propelled βCD-unmodified micromotors. The removal efficiency could reach 98.82% at 4   mg   kg -1 of PHE and maintained beyond 90% within PHE concentrations of 2~20   mg   kg -1 . We anticipate this proof-of-concept study would shed light on treating PAHs-contaminated soil with synthetic micromotors.