Adsorption of MC-LR enabled by customizable 3D printed graphene-coated structures

This proof-of-principle study investigates a novel adsorptive coated polymer structure for the efficient removal of the hazardous algal toxin microcystin-LR (MC-LR), produced by cyanobacteria during harmful algal blooms. While graphene demonstrates high adsorption capacity for MC-LR, its powder form limits practical application due to poor handling and recovery. Here, we introduce a new material combining 3D-printed poly(lactic acid) (PLA) substrates with graphene nanoplatelet (GnP) coatings to enable efficient MC-LR removal in a form factor suitable for field deployment. Surface characterization using laser confocal microscopy, Raman spectroscopy, and thermogravimetric analysis confirmed successful and stable GnP deposition on the printed substrates. Batch adsorption experiments revealed pseudo-second-order kinetics consistent with chemisorption, and a maximum adsorption capacity (qmax) of 596 µg/g, best described by the Langmuir isotherm model. Intraparticle diffusion modeling indicated multi-phase adsorption behavior involving both surface and pore diffusion. Although the graphene coated polymer (GCP) showed lower adsorption capacity compared to the pristine GnP, its structured, retrievable design enables practical use in environmental settings. Notably, over 90% MC-LR removal was achieved in simulated field water after 48 hours. These findings highlight the potential of GCP as a promising platform for scalable water treatment applications targeting algal toxin contamination. Future work will focus on improving adsorption performance through enhanced surface functionalization and pore accessibility to optimize MC-LR removal efficiency. • Graphene-coated 3D-printed composites enable efficient MC-LR toxin removal • Adsorption follows PSO kinetics and Langmuir model with qmax of 596 µg/g • GCPs offer scalable, retrievable platforms for field-deployable HAB treatment