Enhanced Removal of Toxic Heavy Metals Using Swarming Biohybrid Adsorbents

The increasing accumulation of heavy metal ions in our surroundings is posing a serious threat to living systems. Adsorption means based on a variety of micro/nanomaterials and micro/nanomanipulation are being employed for fast and highly efficient removal of various pollutants. Here, a kind of biohybrid adsorbents is developed through in situ growing magnetic Fe3O4 nanoparticles on hydrothermally-treated fungi spores. Such organic/inorganic porous spore@Fe3O4 biohybrid adsorbents (PSFBAs) can effectively adsorb and remove heavy metal ions due to porous structuring and high-adsorbing components. Once combined with a magnetically-driven microrobotic technique, magnetic PSFBAs in controllably collective motion show enhanced adsorption capacity and shorter removal time for multiple heavy metal ions compared to nonmotile counterparts. The corresponding magnetic actuation of collective PSFBAs swarming into a narrow fluidic channel is demonstrated. When utilizing these adsorbents together with magnetically-propelled swarming microrobotic technique, lead ions in contaminated water are rapidly removed from 5 ppm down to 0.9 ppm, superior to untreated and static counterparts. Furthermore, such magnetically-propelled PSFBAs can be reused after facile separation and post-treatment, which is demonstrated by four consecutive cycles. The combination of biological entities and swarming microrobotic techniques would provide a promising avenue for the decontamination of pollutants in environmental remediation.