Fabrication and characterization of 3D-printed PLA-based composite filters for cationic dye removal

This study presents the fabrication and characterization of 3D-printed biodegradable composite filters for the removal of cationic dyes from aqueous solutions. Inspired by the hierarchical structure of tree leaves, the filters were produced using commercially available polylactic acid (PLA) and a PLA/wood composite filament containing 30% wood dust, via fused deposition modeling (FDM). Post-printing modification was performed by treating the filters with aqueous potassium hydroxide (KOH) solutions at varying concentrations (0.1, 0.2, and 0.4 M). The adsorption behavior was assessed using Crystal Violet (CV) as a model cationic dye at concentrations ranging from 10 to 200 mg L^-1 under gravity driven filtration. KOH treatment significantly enhanced the dye adsorption capacity of PLA/wood composite filters, achieving removal efficiencies up to 97.5%. Surface characterization via SEM, FTIR, XRD, and pHpzc analysis confirmed that KOH activation increased surface roughness and introduced functional groups, leading to enhanced electrostatic interaction with cationic species. Moreover, the bioinspired filter geometry with hierarchical porosity contributed to improved mass transfer and dye retention. These findings demonstrate the synergistic effect of material composition, surface modification, and structural design in developing 3D-printed filtration media. The study offers a reproducible and scalable approach for designing polymer-based sorbents for potential applications in water purification.