Crescent-shaped micromotor sorbents with sulfonic acid functionalized convex surface: The synthesis by A Janus emulsion strategy and adsorption for Li.

Self-propelled micromotor (SPM) plays a vital role in recycling of lithium (Li) from wastewater in battery industry. In this work, a crescent-shaped micromotor sorbent (CSMSs) with sulfonic group on convex surface was prepared by Janus emulsion to extract Li. Using sodium p-styrene sulfonate as a functional monomer, well-designed CSMSs was prepared by UV-induced monomer interfacial polymerization, and their pit size can be controlled by adjusting the ratio of two incompatible oils (ethoxylated trimethylolpropane triacrylate and liquid paraffin). In addition, MnO nanoparticles, which embedded into concave interface, generated O bubbles in the presence of HO, and constant circular or line motion of CSMSs was observed. Zeta potential of CSMSs was -51.66 eV at pH = 10, and strong electrostatic attraction between sulfonate groups and Li endowed the maximum monolayer adsorption capacity of 31 mg g at 25 °C. Self-propelled effect further enhanced kinetic performance for Li, and equilibrium time can be reduced from original 10-6.0 h, suggesting autonomous movement achieves rapid mixing and mass transportation. After three adsorption/desorption cycles, the adsorption capacity of the material remains above 90%. This simple and large-scale preparation strategy provided a synthetic method for functional and Janus SPM, as well as sorbents for Li enrichment.