Development of Glycosmis mauritiana plant extract mediated polycrystalline Cerium oxidenanoparticles for the Hydrogen Peroxide Assisted photocatalytic degradation of organic pollutants and biological studies

Abstract

In the presebt study, bio cerium oxide-nanoparticles synthesised by using Glycosmis mauritiana plant extract were compared with Cerium oxide-Nps prepared by chemical method. The ultraviolet - visible, x-ray diffraction, Dynamic light scattering , Zeta Potential, HR - TEM, FT - IR, and Photoluminescencestudies were the characteristics of synthesized Cerium oxide-Nps. UV –Maximum absorption of 318–347 nm was demonstrated by the UV-visible spectrum. The average Cerium oxide-Nps size was about 50 nm, according to dynamic light dispersal studies.and that a possible zeta value of −27.8 mV was obtained for Cerium oxide-Nps. HR-TEM images revealed 45 nm bio cerium oxide-Nps with spherical morphology, as well as the polycrystalline nature of Cerium oxide-Nps, which is consistent with the XRD results. FT - IR analyses have also confirmed the presence of metal oxide.  After being exposed to UV light in the presence of H2O2, biologically synthesised Cerium oxide-Nps demonstrated greater photocatalytic activity for Trypan blue (TB) colour degradation than chemically synthesised Cerium oxide. Only 65 and 51% of TB dye (100 mL; 20 mg L-1) were photocatalytically degraded by bio and chem mediated Cerium oxide NPs in a 60-minute reaction under UV light. However, when H₂O₂ was added, the photocatalytic activity of bio and chem mediated Cerium oxide NPs was significantly improved, reaching 90 and 82% dye removal, respectively.Scavengers of reactive species tests and EPR analysis revealed that the main species in this system are h+ and •OH. The mechanism of TB dye photodegradation in the presence of bio and chem mediated Cerium oxide NPs and H₂O₂ was proposed based on the experimental results. Because electron transfer from the conduction band of bio and chem mediated Cerium oxide NPs to H2O2 is thermodynamically advantageous, the •OH can be formed by either direct water oxidation or H2O2 reduction. Furthermore, H₂O₂ slows e^--hole recombination in bio and chem mediated Cerium oxide NPs, increasing photocatalytic activity. Bio and chem mediated Cerium oxide NPs revealed to be a promising photocatalyst to be tested in the oxidation of emerging pollutants for environmental decontamination due to their high efficiency in degrading TB in water. Trypan blue dye degrades at rates of 82.14 and 92.70% in chem and bio cerium oxide-Nps, respectively. Furthermore, the antibacterial and antioxidant activity of the synthesised Cerium oxide-Nps is investigated. The bio cerium oxide-Nps are antibacterial with the highest antibacterial activity of Pseudomonas aeruginosa(15 ± 0.28 mm) and Staphylococcus aureus(16 ± 0.48 mm) with the lowest concentrations at 100 μl. The Cerium oxide-Npsbio showed greater inhibition of radical DPPH IC₅₀ μg / ml, at 90.41 ± 21. The paper showed that Cerium oxide-Nps have environmentally friendly properties that are useful for dye degradation, antimicrobial and antioxidant activities.