Glass bead-supported Eu3+/Bi2WO6 packed-bed reactor for efficient photocatalytic removal of tetracycline

The widespread use of antibiotics like tetracycline (TC) poses a significant threat to water safety, and while photocatalysis offers a solution, the irrecoverability of powdered catalysts hinders its practical application. To overcome this, a novel packed-bed photocatalytic microreactor (GPR) was constructed by immobilizing a Eu 3+ /Bi 2 WO 6 composite onto glass beads via a sol-gel method. The reactors performance was rigorously evaluated through the continuous degradation of TC. Under optimized conditions (70 μL/min flow rate, 1 mg/L initial concentration), the GPR achieved a remarkable TC degradation efficiency of 98 %, with a high apparent pseudo-first-order rate constant of 0.305 min −1 . This performance represents a 5.2-fold enhancement over conventional slurry reactors. The system also demonstrated exceptional stability, maintaining over 96 % of its initial activity during 12h of continuous operation, and proved effective in complex environments by achieving 96.67 % removal in real wastewater. Computational fluid dynamics simulations corroborated these findings, revealing enhanced mass transfer and optimized flow dynamics within the microchannels. This study successfully demonstrates an efficient, stable, and easily retrievable photocatalytic system, providing a scalable strategy and valuable design principles for advancing continuous-flow water treatment technologies.