Highly Efficient Reductive Detoxification of Sulfamethoxazole by Palladium Nanoparticles Deposited on H2-Transfer Membranes

As one of the most widely used antibiotics, sulfamethoxazole (SMX) is frequently detected in wastewater, imposing a high risk to human health. Current biological and chemical methods for SMX removal are generally lacking in efficiency or are cost-intensive. Here, we demonstrated highly efficient catalytic SMX removal by using a H2-based membrane palladium-film reactor (H2-MPfR), which delivered H2 directly to palladium (Pd0) nanoparticles through bubbleless hollow fibers. The SMX removal rate using this system could reach up to 4.25 mg/L per h, much higher than many other biological or chemical reduction processes. Low H2 partial pressure (e.g., 0.025 MPa under the experimental condition) was proved sufficient for high-rate SMX removal, while appropriate Pd dosage (e.g., 100 mg/dm2) and hydraulic retention time were favorable for maintaining the efficiency of SMX removal. Furthermore, high-performance liquid chromatography and quadrupole-time-of-flight mass spectrometry analyses revealed that the H2-MPfR may remove SMX by destroying the isoxazole ring, and the transformation products have a lower toxicity than SMX. Overall, this study sheds light on catalytic SMX degradation and is helpful in developing cost-effective strategies for removing antibiotics from wastewater.