Excellent successive photo-induced degradation of tetracycline using CuO/g-C3N4 nanocomposites: Synergistic effects of CuO integration and H2O2 in a photo-Fenton system

Abstract

Background

Sustainable and cost-effective approaches have not been fully explored. The photocatalysis process effectively removes toxic effluents and wastes, its efficiency is often hindered by suboptimal reaction parameter optimization, leading to excessive material degradation.

Methods

This research investigates the successful synthesis of g-C₃N₄ (Graphitic carbon nitride), CuO (Copper oxide), and CuO/g-C₃N₄ (Copper oxide/graphitic carbon nitride) nanocomposites by thermal decomposition, co-precipitation method, and ball milling process, respectively. The four distinct CuO/g-C₃N₄ nanocomposites were synthesized, varying CuO amounts (300 mg, 600 mg, 900 mg, and 1200 mg) with a fixed amount of g-C₃N₄ (1 g). The CuO/g-C₃N₄ nanocomposite is utilized for a fast breakdown of tetracycline in wastewater samples in a photo Fenton process by adding H₂O₂ under visible light irradiation.

Significant findings

Transmission electron microscopy analysis shows that CuO nanoflakes have successfully been deposited on g-C₃N₄ nanosheets. Further characterization validated enhancing surface area, visible light activity, favourable charge transfer, efficient charge separation, and reduced charge recombination. The photo-induced degradation of tetracycline was optimized with parameters like CuO anchoring, H₂O₂ addition, and pH, which were methodically examined using kinetic, scavenger tests, and reusability studies. The synergy of CuO and H₂O₂ demonstrated exceptional tetracycline elimination following S-scheme mechanism, achieving 99 % degradation in 15 min. Kinetic studies revealed that the degradation of TC adheres to pseudo-first-order kinetics, hence emphasizing the catalytic efficacy. The rate constant for optimized CuO/g-C₃N₄ nanocomposite was obtained 0.12542 min⁻¹, which is approximately 7 times greater than pure g-C₃N₄ in photo Fenton system. Moreover, the degradation efficiency remained at 91.5 % even after the 4th cycle, which suggests higher reusability and stability. The liquid chromatography–mass spectrometry analysis explained the degradation pathway which identified various intermediates that leads to complete minerlization. The findings confirm that CuO/g-C₃N₄ nanocomposites can be effective for high-efficiency antibiotic degradation, offering a scalable and sustainable choice for water treatment applications.