Green synthesis of Pt-Cu-based bimetallic nanoparticles and magnetic biochar-supported nanocomposites for antioxidant and dye degradation applications

The discharge of dye-containing wastewater poses significant risks to both ecological systems and human health, underscoring the urgent need to develop efficient and sustainable degradation methods for such pollutants. Herein, platinum nanoparticles (Pt NPs), bimetallic platinum-copper nanoparticles (Pt-Cu NPs) with varying molar ratios, and magnetic nanocomposites were successfully synthesized using Aloe vera extract. In three different in vitro antioxidant assays, pure Pt NPs demonstrated the highest antioxidant activity. The efficiency of dye degradation by nanomaterials in a hydrogen peroxide-based Fenton-like system was found to be strongly dependent on the reaction conditions. Among the bimetallic nanoparticles, the Pt-Cu (1:2) sample exhibited the highest catalytic efficiency, achieving complete degradation of methylene blue (MB) within 80 min and methyl orange (MO) within 390 min, with degradation rates of 96.32% and 94.86%, respectively. Remarkably, when the magnetic nanocomposite was employed as a catalyst under identical reaction conditions, the degradation time for MB was significantly reduced to 15 min and that for MO to 24 min, with corresponding degradation rates of 96.93% and 95.2%. Moreover, both the nanoparticles and magnetic composite materials demonstrated favorable recyclability and reusability, and break through the narrow pH condition limitations of the traditional Fenton method. Aloe vera extract was employed for the green synthesis of nanomaterials, which demonstrated favorable performance in both antioxidant activity and dye degradation. This approach offers a more economical, facile, and rapid alternative for functional nanomaterial preparation.