Efficient Degradation of Carbamazepine in Continuous and Batch Modes by Laccase-Photo-Fenton-Intensified Hybrid Treatment

Despite advances in the removal of pharmaceutical residues from aqueous effluents, carbamazepine (CBZ) remains challenging due to its persistence. The low removal efficiency of conventional wastewater treatments reinforces the need to develop innovative approaches, such as hybrid systems. This study combined photo-Fenton reactions with the enzyme laccase (Lac) to effectively remove CBZ from aqueous solutions in batch and continuous-flow regimes. Lac was immobilized on functionalized magnetite nanoparticles (MNPs) to improve stability and operational efficiency. Investigation of the effects of pH, temperature, UVC radiation, and H₂O₂ dose on Lac activity revealed promising results. Immobilized Lac retained 77.7% of its initial activity after 60 min of UVC exposure. In contrast, the free enzyme lost its activity within 30 min of exposure. In batch mode, the Lac-MNPs/UVC/H₂O₂ system with 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) as the inducer degraded 91.9% of CBZ in 15 min of reaction at neutral pH. For continuous operation mode, optimization based on a Central Composite Rotatable Design achieved 91.1% CBZ removal at 10 min space-time, 20:1 H₂O₂:CBZ molar ratio, and 30 μmol L^-1 ABTS. The high removal efficiency in both batch and continuous modes indicates the potential application of the developed hybrid laccase-photo-Fenton treatment for effective CBZ degradation.