Enhanced Removal\nof Anionic Pollutants Using Active\nPropulsion of Patchy ZIF‑8 Microparticles in Electric Field

Active colloids are microparticles capable of self-propelling\nat\nlow Reynolds numbers, presenting unique opportunities to enhance adsorption\nprocesses at the microscale. In this study, we develop patchy zeolitic\nimidazolate framework-8 (ZIF-8) microparticles with asymmetrically\ndeposited gold patches as a class of active adsorbents for the removal\nof ionic pollutants from water. By applying an alternating current\nelectric field, these patchy ZIF-8 particles propel via induced-charge\nelectrophoresis, exhibiting linear and helical propulsion trajectories\nbased on the geometric configuration of the patch. Our experiments\ndemonstrate that this electric field-driven active propulsion significantly\naccelerates the adsorption kinetics of anions, including perchlorate,\nsulfide, and fluoride. Our study provides insights into the potential\nof active particles to overcome mass transport limitations in pollutant\nadsorption, highlighting a fuel-free approach for targeted water remediation.\nWe present the design principles of patchy ZIF-8 particles, explore\nthe influence of particle symmetry on propulsion dynamics, and demonstrate\nthe practical implications of using active colloids for environmental\nremediation. These findings lay the groundwork for future research\nfocused on optimizing particle design and expanding the applicability\nof active porous adsorbents to a broader range of pollutant removal\nchallenges.