Calcined Aluminum Sludge as a Heterogeneous Fenton-Like Catalyst for Methylene Blue Degradation by Three-Dimensional Electrochemical System

In recent years, aluminum sludge has been studied as a waste in the field of adsorption. In this study, it was prepared as a catalyst for the degradation of dye wastewater in a heterogeneous Fenton system. In this paper, a calcined aluminum sludge (CAS-700) catalyst was successfully prepared at high temperature. The physical and chemical properties of CAS-700 catalyst before and after the modification were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscope (SEM) and Brunner–Emmet–Teller (BET), and the methylene blue (MB) wastewater purification test was carried out through the heterogeneous Fenton system. The optimal experimental conditions are obtained by the response surface method and single-factor experiment. The electrode quantity of CAS-700 is 200 g/L, MB concentration is 20 mg/L, electrolyte concentration (Na2SO4) is 0.14 mol/L, voltage is 8 V, and acidic conditions are removed. The rate can reach 91.26%, which is 32% higher than the traditional two-dimensional system. In addition, CAS-700 exhibits a high catalytic efficiency ( > 88%) after six cycles. Finally, high-performance liquid chromatography-mass spectrometry (HPLC–MS) was performed to reveal the degradation pathway of MB. This not only provides a new and efficient catalyst but also provides a way for the resource utilization of aluminum sludge in water plants, in accordance with “waste for waste treatment.”