Natural sustainable and eco-friendly catalyst utilizing lupine peel waste for efficient degradation of organic pollutants via Fenton-like reactions

Abstract

Peels of agricultural wastes are gaining new outlook recognition as affordable and effective catalysts for organic pollutants. This study investigates the potential of untreated (S1) and alkaline-treated Lupine Peels Powder (S2) as an eco-friendly biomaterial for degrading cationic methylene blue (MB) from wastewater. The findings pertain to the catalytic degradation of MB and the improved degradation observed following alkaline treatment. The presence of active manganese sites on the surface of S2 samples enhances the catalytic degradation of MB; as manganese sites accelerate H2O2 breakdown, forming ˙OH radicals that degrade MB. Optimizing H2O2 concentration, MB concentration, and temperature is crucial for high efficiency. The optimum removal efficiency reaches (82.37%) occurs at 25 °C with 6% of H2O2 for MB with Co= 15 ppm which is very close to 4% of H2O2 so, the optimum concentration of H2O2 is 4% for Co ranges from 5 to 15 ppm. Higher MB concentrations and H2O2 levels improve efficiency to a specific limit, but higher temperatures reduce it by accelerating H2O2 decomposition. XPS characterization analysis reveals that NaOH treatment increases the visibility of metal elements such as manganese, copper, and iron, providing better insights into the surface composition and its catalytic potential for MB degradation. In general, NaOH treatment enhances MB removal by improving the surface activity of lupine peels, likely through structural and compositional modifications.