Preparation of Fe₃O₄/C Composite Material from Red Mud for the Degradation of Acid Orange 7

This study presents a novel Fe₃O₄/C composite material synthesized from red mud through a process of magnetic roasting and separation. The research explores the impact of Fe₃O₄/C dosages, sodium persulfate (PS) concentrations, and initial solution pH on the chemical oxygen demand (COD) removal efficiency using Acid Orange 7 as a model pollutant. Optimal conditions were identified as 3 g/L Fe₃O₄/C, 20 mM PS, and an initial pH of 2, achieving a 94.11% COD removal efficiency within 30 min. X-ray diffraction and photoelectron spectroscopy analyses confirmed that the magnetization roasting process effectively transformed red mud's ferric oxide (Fe₂O₃) into magnetite (Fe₃O₄). Concurrently, Fe₃O₄ interacted with residual carbon to form the Fe₃O₄/C composite. This composite demonstrated superior catalytic performance, along with excellent recyclability and reusability.