Exploring UV-light-driven photocatalytic activity of BiOBr supported on ZIF-67 as catalyst for amitriptyline degradation

Organic contaminants classified as contaminants of emerging concern (CECs) represent a growing environmental challenge due to their persistence and low removal efficiency in conventional water treatment systems. In this study, a BiOBr@ZIF-67 composite photocatalyst was developed and evaluated for the degradation of the pharmaceutical amitriptyline in aqueous media. Structural and morphological characterizations confirmed the successful deposition of BiOBr particles onto the ZIF-67 surface, forming a well-integrated composite. Optical analysis indicated that BiOBr and the BiOBr@10% ZIF-67 composite are mainly active under UV irradiation (3,19 eV), while ZIF-67 acts as structural support contributing to improved interfacial properties. The composite photocatalyst exhibited enhanced photocatalytic performance, achieving 45% degradation efficiency, higher than that obtained with the individual components, demonstrating a synergistic effect between the phases. The degradation efficiency further increased to 52% in the presence of persulfate, indicating improved reactive species generation. Moreover, a removal efficiency of 60% was achieved in tap water, confirming the applicability of the system under more realistic conditions. The photocatalytic reactions followed pseudo-first-order kinetics, and the catalyst showed good stability and reusability after recycling tests. These results highlight the potential of the BiOBr@ZIF-67 composite as an efficient and cost-effective material for the treatment of recalcitrant pharmaceutical contaminants.