Efficient synergistic degradation of tetracycline hydrochloride by protonated g-C3N4 and Chlorella pyrenoidosa: Kinetics and mechanism

The combined application of microalgae and photocatalytic materials in degrading and detoxifying organic pollutants has shown good application prospects. However, the combined application of the two technologies had problems such as the difficult recovery of photocatalytic materials and poor biocompatibility. Therefore, this study combined the protonated graphitized carbon nitride (P-g-C3N4) with Chlorella pyrenoidosa through electrostatic adsorption to form a new photocatalytic microalgae composite degradation system. At the same time, Chlorella pyrenoidosa enhanced the photocatalytic activity of P-g-C3N4 through EOMs photosensitization and electron transfer, and there was a synergistic effect between P-g-C3N4 and Chlorella pyrenoidosa, which realized the efficient degradation and mineralization of tetracycline hydrochloride. Meanwhile, the new compound degradation system had a good solid–liquid separation effect and recycling efficiency. Electron paramagnetic resonance (EPR) and free radical capture experiments showed that superoxide radical was dominant in the reaction pathway. The research results can provide theoretical and practical support for the application of the combined technology of microalgae and photocatalytic materials.