Synthesis of iron oxide nanoparticles using <i>Hydrilla verticillata</i> (L.f) Royle plant extract and determining its efficiency to treat fabric dyeing effluent

Abstract In the present investigation, Fe 3 O 4 nanoparticles were synthesized via co-precipitation method using an extract obtained from the freshwater aquatic flora Hydrilla verticillata (L.f) Royle and subjected to various characterization studies, including UV-DRS, XRD, FTIR, EDX, SEM, followed by HR-TEM. The UV-DRS spectrum was found in the range of 375 nm–737 nm, and the optical reflectance band gap energy was determined by the Kubelka-Munk equation, and the value was 1.74449 eV. The XRD pattern of Fe 3 O 4 nanoentities showed diffraction peaks in the regions of 2 θ at 30.764°, 36.324°, 43.835°, 57.743°, and 63.469° corresponding to crystal plane miller indices (220), (311), (004), (115), and (404), respectively (JCPDS File No. 01-076-1470). The crystallite structure of the nanoparticle was tetragonal, and the lattice constant measurements were found to be a = 8.471 Å, b = 8.471 Å and c = 8.396 Å. The crystallite structure of the particle was 7.5 nm. The peak observed at 590 cm −1 , and 605 cm −1 is consequents to the strong band for Fe–O–Fe bonding. The EDX analysis showed 67.12 % of Fe and 32.88 % of oxygen molecule. The dispersed irregular spherical form of morphology was observed in the SEM result. From the HR-TEM results, the morphological structure and size of the particle were found to be spherical and 11.57 nm. The SAED pattern indicates the polycrystalline properties of the nanoparticles. The application of Fe 3 O 4 nanoentity resulted in the reduction of 71 % of color, 69 % of solids in a dissolved state, 73 % of organic matter that could be degraded by strong oxidizing agents, and 37 % of Cl − ion from the wastewater generated during fabric dyeing processes. The antibacterial activity of the particle showed a better inhibition effect (15 mm) against Escherichia coli . After the treatment phase, the Fe 3 O 4 NPs that have been used can be retrieved by applying an apt magnetic field, which allows for their re-utilization in the remediation of dyeing wastewater. Henceforth, this is an environmentally friendly approach for dyeing industry waste water treatment, which enhances the conservation of existing water and land resource for sustainable development.