Enhanced Removal of Anionic Pollutants Using Active Propulsion of Patchy ZIF-8 Microparticles in Electric Field

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