An experimental study on the use of iron oxide magnetic nanoparticles synthesized through watermelon rind extracts for industrial applications

•WRE@Fe3O4 MNPs prepared by green extraction method.•The synthesized iron oxide nanoparticles are conjugated with FITC for helping to visible.•Green synthesized WRE@Fe3O4 MNPs show magnetic behavior.•Experimental studies exhibit that the cracks between 1.29 mm and 1.55 mm can be detected in the test block during MPI testing. In this study, an easy and eco-friendly way for the synthesis of magnetic nanoparticles was investigated and mainly focused on its use on magnetic particle inspection (MPI) as a fluorescent magnetic particle. For this purpose, iron oxide magnetic nanoparticles (Fe3O4 MNPs) were prepared via rapid and green route using watermelon rinds extract (WRE). The synthesized WRE@Fe3O4 MNPs have been characterized by Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and Dynamic light scattering (DLS). From the SEM images of the WRE@Fe3O4 MNPs, it has been shown that particle size was ranging from 50 nm to 100 nm. EDS spectrum indeed confirmed the presence of significant amounts of Fe and O. The average particle size was found to be 554.8 nm by DLS method. The magnetic property of WRE@Fe3O4 MNPs was analyzed by Vibrating sample magnetometer (VSM). The analysis of synthesized nanoparticles showed an amount of 24.35 emu/g for magnetic saturation. All of the results, the green synthesized WRE@Fe3O4 MNPs demonstrated good potential for identifying cracks in the test block during MPI testing. Thus, the cracks between 1.29 and 1.55 mm in the test block were successfully identified.