Enhanced removal of emerging pollutants through visible light-activated carbon nitride materials immobilized over 3D printed structures

This study investigates the performance of carbon nitride (CN) photocatalysts immobilized on 3D printed cylindrical supports for the removal of selected emerging pollutants, namely venlafaxine (VFX), citalopram (CTP), fluoxetine (FXT), and carbamazepine (CBZ), due to their rising consumption as antidepressants and the significant concerns for public health and the environment, mainly due to the direct impact of their presence in surface waters. The CN photocatalysts were synthesized using two precursors (dicyandiamide and urea), forming four different CN materials. Among the immobilized CN photocatalysts tested, the bulk CN prepared from urea (CNB-U/PLA) revealed the highest efficiency for the removal of VFX as the target antidepressant (above 90% after 30 min), which was ascribed to the lower recombination of photogenerated charges of this photocatalyst. The reuse tests confirmed the robust and effective photocatalytic performance of the CNB-U/PLA photocatalyst over multiple cycles, while its versatility with different support configurations demonstrates its adaptability and broad potential for various photocatalytic applications. The simultaneous removal of the four antidepressants was performed at low concentrations (1.8 μM), employing the most efficient immobilized photocatalyst (CNB-U/PLA), yielding remarkably high conversion rates (above 90% for VFX, CTP, and FXT, and around 70% for CBZ, after 60 min) under visible irradiation. The results demonstrate the ability of the immobilized CN system to effectively eliminate contaminants with different chemical properties. This study emphasizes the potential of this approach for comprehensive emerging pollutants removal, highlighting its significance in water treatment and environmental remediation strategies.