Preparation of Fe-enhanced manganese sand-based ceramic catalytic membranes for tetracycline removal from water

Fe-enhancement improved the performance of the ceramic membranes. • Modifying manganese sand method is the optimal Fe-enhancement pathway. • Water flux and TC removal rate increased to 746.24−949.76 L m −2  h −1 and 72%−78%. • Fe-enhancement initiated the Fe-Mn synergistic catalysis. In this study, three types of Fe-enhanced natural manganese sand-based ceramic membranes were prepared by the methods of integrated sintering, surface impregnation, and modifying manganese sand, respectively, and were used to activate peroxymonosulfate for tetracycline (TC) removal from water. The membrane catalytic performance, anti-fouling ability, catalytic mechanisms, and the differences among the enhancement methods, were investigated. After Fe enhancement, the membrane porosity increased from 7.20% to 14.72%–20.20%, while the water contact angle decreased from 77.23° to 45.19–57.81°, leading to a significant improvement in pure water flux from 180.91 L m −2  h −1 to 746.24–949.76 L m −2  h −1 . Additionally, the TC removal rate increased from 54% to 72%–78% and the water flux attenuation was significantly mitigated, with the J/J 0 rising from 0.11 to 0.50. Multi-cycle repeated experiments showed that the ceramic membranes exhibited good catalytic stability. The average removal rate of TC remained above 68% after six successive runs. The iron leaching concentrations of all the membranes, except for the NMSFe-CM, were below 0.057 mg/L within 24 h, demonstrating their excellent structural stability. Mechanism analysis indicates that Fe enhancement initiates a unique bimetallic synergy between Fe and Mn active sites, which promotes the generation of reactive oxygen species, especially singlet oxygen, thereby improving the degradation efficiency of tetracycline. As Fe 3+ was uniformly distributed on the surface of manganese sand and fully interacted with the Mn active sites, the membrane prepared by the modified manganese sand method exhibited optimal catalytic activity and good iron stability. A new insight into the preparation of natural mineral ceramic membranes and the reliable loading of catalytic materials within the membrane matrix was provided in this study. Download: Download high-res image (310KB) Download: Download full-size image