(180j) Sunlight-Induced Photocatalysis of Azithromycin: Role of Cnc-TiO2 Nanocomposite

Antibiotics play a crucial role in treating bacterial infections, but their overuse can contaminate our water sources. This contamination raises concerns about the development of antibiotic resistance, which is becoming a global issue. Azithromycin (AZM), a widely used antibiotic, has been found in both wastewater and natural water bodies, highlighting the need for practical solutions to mitigate its environmental impacts. TiO₂ nanoparticles are recognized for their photocatalytic efficiency. However, they encounter practical challenges, such as difficulty in recovery, which can lead to secondary pollution. Thus, it is essential to develop an appropriate substrate material or scaffold that can match the catalytic performance of these nanoparticles. This study explores the use of innovative cellulose nanocrystals (CNC) as a framework for creating composites with high-loading TiO₂ nanoparticles, offering a simple and efficient solution for the degradation of AZM. This study explored the effectiveness of sunlight for the photocatalytic degradation of AZM in water. The synthesized nanocomposite served as a catalyst for breaking down AZM. Maximum removal efficiency of 98.8% was achieved in 5 hours at a catalyst dose of 175 mg/L for an AZM solution with 10 mg/L concentration. Scavenger studies identified O₂^•- and •OH radicals as the primary active species. Further analysis via liquid chromatography-tandem mass spectrometry (LC-MS/MS) revealed the pathways and intermediate products involved in the degradation. Toxicity assessments indicated that harmful byproducts decreased over time, and reusability study confirmed that the catalyst could be reused effectively. In conclusion, CNC-TiO₂ nanocomposites are highly effective catalysts for the photocatalytic degradation of AZM. The developed method further ensures the hygiene of water sources and prevents the spread of antibiotic resistance.