Biosynthesis and characterization of MnO2 and Zn/Mn2O4 NPs using Ziziphus spina-Christi aqueous leaves extract: Effect of decoration on photodegradation activity against various organic dyes
Rouiha Zohra, Souhaila Meneceur, Laouini Salah Eddine, Abderrhmane Bouafia, Hamdi Ali Mohammed, Gamil Gamal Hasan
Abstract
An aqueous leaf extract of Ziziphus spina-Christi is used to synthesize manganese oxide nanoparticles (MnO 2 NPs) and zinc-coated manganese oxide nanoparticles (Zn/Mn 2 O 4 NC). The study aims to investigate the photocatalytic degradation efficiency of MnO 2 NPs and Zn/Mn2O4 NC in relation to the azo dyes methylene blue (MB), m-Toluidine (mT), and P-Toluidine (pT). X-ray diffraction analysis (XRD) confirmed the crystalline nature of the biosynthesized MnO2 NPs and Zn/Mn 2 O 4 , revealing their respective crystallite sizes to be approximately 14.65 nm and 22.97 nm. The scanning electron microscope (SEM) images demonstrated that the MnO 2 NPs exhibit a tetragonal and spherical shape, while the Zn/Mn 2 O 4 particles possess a spherical shape. UV–vis spectroscopy measurements indicated that the MnO 2 NPs and Zn/Mn 2 O 4 exhibit indirect bandgaps with energy values of 1.46 eV and 1.14 eV, respectively. Fourier transform infrared (FTIR) analysis revealed the presence of organic compounds containing C O and OH groups, such as carbohydrates, phenolic acids, tannins, and flavonoids derived from Ziziphus spina-Christi , suggesting a high likelihood of stability for the biosynthetic MnO 2 and Zn/Mn 2 O 4 materials. Interestingly, the photocatalytic degradation of the biosynthetic MnO 2 and Zn/Mn 2 O 4 provided good efficacy against the Methylene Blue (MB), m-Toluidine (mT), and P-Toluidine (pT) where the Zn/Mn 2 O 4 exhibit an excellent degradation were 99.2, 99.8 and 98.4 % after 75 min. The biosynthetic MnO 2 NPs and Zn/Mn 2 O 4 NCs resulting from using aqueous ZSCLE were cost-effective and eco-friendly, and the decoration of MnO 2 NPs by Zn improved their effectiveness.