Recycling of Solid and Electronic Waste for the Synthesis of CoFe2O4/γ-Fe2O3@SiO2/NaAlSi3O8 and Its Application as a Photocatalyst and Pseudocapacitor

Disposing of industrial and electronic waste poses a significant environmental challenge. A sustainable solution involves converting waste into raw materials for new components. This study synthesized the mixed oxide CoFe2O4/γ-Fe2O3@SiO2/NaAlSi3O8 using abrasive sludge from the marble and granite industry and spent lithium-ion battery cathode material. X-ray diffraction (XRD) identified LiCoO2 and graphite C in the battery cathode, while abrasive sludge contained iron (α-Fe), magnetite (Fe3O4), albite (NaAlSi3O8), mica (KAl2(AlSi3O10)(OH)2), calcite (CaCO3), and dolomite (CaMg(CO3)2). The structure and morphology of the mixed oxide revealed clusters of nanometric particles. The mixed oxide had a band gap of 3.1 eV. It was applied as a catalyst for dye degradation via the photo-Fenton process and as an electrochemical pseudocapacitor. Methylene blue (MB) decolorization reached 100% after 50 min, with pseudo-first-order kinetics (coefficient of determination (R2 ) = 0.98). This efficiency remained even after six successive decolorization cycles. Electrochemical analysis revealed a maximum capacitance of 45.50 F g–1, specific capacity of 87.26 mAh g–1, energy density of 36.41 Wh kg–1, and coulombic efficiency of 88.81%. These findings highlight its reversible pseudocapacitive profile and efficiency, underscoring its importance for sustainable development and circular economy.