Photocatalytic Degradation of Polycyclic Aromatic Hydrocarbons in Water by 3D Printed TiO₂Composites

Recent progress in developing composites embedded with photocatalysts indicates application for wastewater treatment. However, significant gaps remain in developing effective photocatalyst-polymer composites for use as customizable, deployable, and retrievable structures for mitigating environmental contamination. The goal of this study was to generate and evaluate the performance of 3D printed TiO2 composites for degrading polycyclic aromatic hydrocarbons (PAHs) in waters affected by contaminated sediment. Photocatalytic structures were fabricated using polylactic acid (PLA) compounded with TiO2 nanoparticles as filament feedstock and printed using a benchtop 3D printer. Photocatalysis and photolysis experiments were conducted in controlled environmental chambers under full spectrum light (λ = 280-750 nm). 3D printed PLA-TiO2 disks increased the degradation kinetics (compared to photolysis) of a complex mixture of 4- to 5-ring PAHs achieving nondetectable concentrations within hours to days. The PAH removal rate was relatively rapid, with 3D printed PLA-TiO2 treatments achieving degradation half-lives within ∼6 to ∼24 h. After 48 h of treatment, both photolysis and photocatalysis eliminated toxicity to Ceriodaphnia dubia. These data indicate the potential application of 3D printable photocatalytic polymers to mitigate problematic organic constituents in water and highlight the benefits of additive manufacturing to rapidly prototype and optimize innovative structures.