Efficient photodegradation of acid orange 7 in water using a facile ultrasound-assisted microwave-combustion synthesized Ag-ZnAl2-xFexO4 solid-solution photocatalyst

This study explores the development of Ag-ZnAl_2-xFexO₄ solid-solution photocatalysts for Acid Orange 7 (AO7) degradation under visible light irradiation. The microwave auto-combustion method was employed to synthesize these photocatalysts, allowing for the investigation of the influence of Fe substitution (x) on their properties and performance. Characterization techniques revealed a trade-off between Fe content, surface area, pore size, and light absorption capacity. The Ag-ZnAlFeO₄ variant achieved an optimal balance, demonstrating exceptional photocatalytic activity for AO7 degradation. This optimized photocatalyst achieved a removal efficiency of 99.3 % under neutral pH conditions, highlighting its effectiveness and potential for practical applications. Interestingly, the mineralization efficiency of AO7 reached 85.2 % after 160 minutes of reaction time. Kinetic studies supported the superior performance of Ag-ZnAlFeO₄, attributing its success to its favorable morphology, high surface area, strong light absorption, and minimal electron-hole pair recombination. The proposed degradation mechanism involves light absorption, generation of electron-hole pairs, and their subsequent reactions with water and oxygen molecules to degrade AO7. This work establishes Ag-ZnAl_2-xFexO₄, particularly Ag-ZnAlFeO₄, as a promising visible-light photocatalyst for the efficient degradation of organic pollutants.