Microfluidic synthesis of graphene oxide/MnO2-incorporated self-propelling micromotors for organic dye removal

Abstract

Dye contamination in water poses a significant threat to public health and the environment. Hence, numerous studies have attempted to develop new systems and materials for the rapid and effective removal of dyes from contaminated water bodies. However, most designs involve multiple intricate steps and sophisticated equipment, which makes mass production of these removal systems highly challenging. In this study, using a microfluidic technique, we synthesized asymmetrically dimpled microbead-based micromotors capable of removing substantial amounts of contaminants from polluted water via MnO₂-mediated fuel decomposition. To endow the micromotors with wastewater treatment properties, the well-established adsorbent graphene oxide (GO) and catalytic MnO₂ nanoparticles were simultaneously incorporated into a poly(ethylene glycol) diacrylate matrix. Subsequently, using a microfluidic technique, monodisperse and asymmetrically shape-regulated micromotors were generated based on aqueous two-phase separation and subsequent UV solidification, in which the polymer matrix could be easily tuned for wastewater treatment by incorporating functional nanomaterials. In our designed micromotors, GO functions as an adsorbent to remove dye contaminants from the environment, whereas MnO₂ catalyzes H₂O₂ to produce O₂ bubbles, the driving force for the self-propulsion of the micromotors; promotes mixing; and enhances the dye molecule absorption process by GO. As a result, compared to the non-MnO₂ stationary (solely GO-loaded) microbeads, the micromotors exhibited a significantly higher water remediation performance. In addition, by refining the morphology of the micromotors to enable their active motion at even lower fuel concentrations, this technology is anticipated to be utilized extensively for bio- and environment-related applications.