Upcycling Red\nMud into a Stable Electro-Fenton Catalyst\nvia Ingenious Sn Doping for Efficient Antibiotic Wastewater Treatment

The limited stability of catalysts and their high operational\ncosts\npresent significant challenges to the widespread application of heterogeneous\nelectro-Fenton (HEF) in practical water treatment. Herein, we developed\na scalable production (∼1 kg) of a Sn-doped red mud (RM-Sn1.5)\ncatalyst via a straightforward methodology for the HEF system aimed\nat antibiotic wastewater purification. The RM-Sn1.5 catalyst could\nremove over 90% of nine antibiotics and two phenolic compounds from\nwater within 90 min, with an electrical energy consumption of 7.37\nkWh·m<sup>–3</sup> per order. The incorporation of Sn\ninduced the formation of intrinsic oxygen vacancies, which act as\nelectron donors, significantly enhancing the internal electron transfer\nbetween Sn and Fe, thereby ensuring sustainable iron cycling to generate\nhydroxyl radicals. Importantly, the RM-Sn1.5 catalyst demonstrated\noutstanding catalytic performance, even after 30 cycles of reuse and\n6 months of placement. During the treatment of actual pharmaceutical\nwastewater, 54.5% of COD removal was achieved in just 90 min. This\nstudy provides a novel approach to converting industrial waste into\na low-cost, sustainable catalyst for the economic treatment of practical\nwastewater.