Fuel-free magnetic COF–alginate microbead motors for active removal of dual carcinogenic pollutants

The presence of carcinogenic and persistent micropollutants in the aquatic systems exist at ng–μg·L −1 levels, yet their active, selective, and recoverable removal remains challenging. Micro/nanomotors (MNMs) offer propulsion-enhanced mass transfer mechanisms in pollutants removal. However, widely explored metal–organic framework (MOF-MNMs) suffers from chemical/structural instability, multistep or high-temperature fabrications, and difficult in post-use recovery. Owing to the covalent organic frameworks (COFs) superior intrinsic stability which can be considered as alternative emerging MNMs. However, some of the conventional COF-MNMs are hindered by hydrophobicity, limited adsorption, reliance on peroxide or light fuels, expensive building blocks and face recovery issues (due to powder nature). Here we report a mesoporous COF functionalized with magnetic particles (MP-COF) and ionically crosslinked with alginate biopolymer to obtain fuel-free, steerable, retrievable microbead motors. Under rotating field, they navigate in complex environment achieving ~58 % DOX removal in 15 min and up to 72 % DOX and 86 % CV with modest removal performances in river, sea, rain and tap waters and only a 10–20 % decline in natural organic matter. Further, synergistic π–π, hydrogen bonding, electrostatic and pore-filling interactions underpin adsorption mechanisms and validated with better reusable feature. This magnetically recoverable COF microbead motors platform overcomes several limitations providing a modular route toward an active remediation approach for dual carcinogenic pollutants in aqueous environments.