Recycling Waste Aluminium Foil to Bio-Acceptable Nano Photocatalyst [Aluminium oxide (Al2O3) & Aluminium oxyhydroxide (AlOOH)]; Dye Degradation as Proof-of-Concept

Abstract

The surge in the world's population resulting from urbanization and industrialization has led to a significant uptick in water and soil pollution. Aligning with the United Nations goals of sustainability, it is recommended to earnestly investigate innovative methods for repurposing waste into beneficial materials and effective catalysts that are compatible with ecosystems and capable of efficiently decomposing dyes. Additionally, aligning with the objectives of a sustainable society, this study serves as a prototype for repurposing discarded aluminium foil-an everyday single-use material contributing to landfill accumulation-into aluminium oxide (Al2O3) and aluminium oxyhydroxide (AlOOH) nanocatalysts, intended for efficient photodegradation applications. Both Al2O3 and AlOOH nano-systems were synthesized using a well-optimized chemistry route. The developed nano-systems were characterized using FTIR, EDX mapping, XRD, FE-SEM, and TGA/DTA which found the bonds, composition, structure, morphology of the particles, and thermal stability, respectively. These particles are used for the degradation of cationic Methylene Blue (MB) in neutral (pH 7), basic (pH 9), and acidic (pH 5) mediums. Liquid chromatography mass spectrometry (LC-MS) was performed to check the MB intermediate product formation on photodegradation. The findings suggest that exposing cationic MB to light in neutral pH conditions with Al2O3 is highly effective, with a dye degradation rate of 99.29%. Exposing MB to the dark in neutral conditions with AlOOH is the least effective, with a dye degradation rate of 6.64%. As the pH is made more acidic and/or basic, the effectiveness of Al2O3 and AlOOH also slightly changes. The outcomes related with both reusability and toxicity studies also proven positive acceptability of the developed systems. The degradation using both compounds led to more germination when compared to MB, and both compounds showed outstanding reusability. The research emphasizes the importance of sustainable materials synthesis and offers valuable insights for the development of efficient photocatalysts tailored for specific environmental conditions in the context of dye degradation.