Green synthesis and characterization of manganese oxide nanoparticles using Equisetum diffusum D. Don. extract for...

Industrial dyes and organic pollutants pose a significant water contamination and environmental challenges. Herein, manganese oxide nanoparticles (MnO₂NPs) were biosynthesized using Equisetum diffusum extract as the reducing and stabilizing agents. The successful biosynthesis of MnO₂NPs was confirmed by a characteristic UV-Vis absorption peak at 416 nm, a band gap of 2.4 eV, and XRD analysis, which showed a tetragonal crystalline phase with an average crystallite size of 15 nm. SEM and DLS analyses revealed spherical nanoparticles with average sizes of 55.73 ± 1.17 nm and 66.2 ± 3.4 nm, respectively, while a zeta potential of - 63.4 ± 5.8 mV indicated excellent colloidal stability. The biosynthesized MnO₂NPs were investigated for their photocatalytic efficiency in the degradation of methylene blue (MB), methyl orange (MO), and para-nitrophenol (PNP) under sunlight irradiation. The biosynthesized MnO₂NPs exhibited improved degradation efficiencies of 92 for MB, 93 for MO, and 90% for PNP in 100 min under pH 7 conditions. At a dye concentration of 10 mg/L, the degradation of MB, MO, and PNP was 92, 93, and 90%, respectively. Additionally, MnO₂NPs dosage of 10 mg/L, the degradation of MB, MO, and PNP reached 92, 93, and 91%, respectively. Moreover, recyclability studies demonstrated minimal loss of catalytic activity over five consecutive cycles, indicating the stability of the MnO₂NPs. This eco-friendly synthesis of MnO₂NPs offers a sustainable and cost-effective solution for wastewater treatment, highlighting their potential application in environmental remediation and pollutant degradation.