LCQDs modified Bi2MoO6 hydrangea composite photocatalyst for tetracycline degradation from wastewater: Performance, efficiency, and adsorption synergistic photocatalytic mechanism

This study used alkaline lignin as the carbon source for preparing alkaline lignin carbon quantum dots (LCQDs) based on the solvothermal method. To achieve efficient photocatalytic degradation of tetracyclic hydrochloride antibiotics (TCH), hydrangea-shaped LCQDs/Bi2MoO6 composites were prepared in situ by the solvothermal method exploiting the optical properties of LCQDs. The composite material was systematically characterized using XRD, FTIR, XPS, SEM, TEM, EIS, nitrogen adsorption-desorption testing, and UV-vis DRS to determine its crystal structure, microstructure, and optoelectronic properties. The results show that the sample has high purity and good crystallinity. The experiment on photocatalytic degradation further demonstrated that the LCQDs/ Bi2MoO6 composite material modified with LCQDs exhibited superior photocatalytic activity compared to a single Bi2MoO6. Among them, BMO/LCQDs-7 showed the best effect. After 120 min of illumination, the rate of TCH removal through photocatalysis was 98.76%, with a degradation rate constant: K= 0.026 min-1. After five cycles, the removal rate of TCH can still be maintained at 79.35%. The photocatalytic degradation of TCH has been demonstrated through EPR and LC-MS experiments primarily caused by h+ and & sdot;O2- .