Heterogeneous Activation of Sulfite by a Three-Dimensional Printed Hierarchically Porous Copper Catalyst for the Degradation of Tetracycline Hydrochloride in Water

Sulfite [S(IV)]-based advanced oxidation processes (AOPs) have emerged as a promising strategy to address ever-growing water pollution. In this study, a novel three-dimensional hierarchical porous copper (3D-Cu) catalyst was fabricated via laser 3D printing. The 3D-Cu catalyst demonstrated remarkable efficiency as an S(IV) activator for the efficient removal of tetracycline hydrochloride (TC), comparable to that of copper powder under similar conditions. Impressively, the 3D-Cu catalyst manifested superb stability and reusability, maintaining a high reactivity even after 40 successive cycles. The results indicated that Cu(II) sites functioned as active sites for S(IV) oxidative activation, with the unique 3D hierarchically porous structures enhancing accessibility to these active sites and facilitating the migration of S(IV) and contaminants. Furthermore, ryegrass seeds and Vibrio fischeri exposure experiments suggested that the mineralization process of TC could effectively reduce its biotoxicity. Additionally, the CaSO3/3D-Cu system exhibited excellent adaptability to different natural water matrices and was even effective in eliminating contaminants in actual wastewater. Overall, this study provides a new strategy for the preparation of efficient and durable heterogeneous S(IV) activators and advances the application of S(IV)-AOPs in real-world wastewater treatment.