The green method was chosen for the preparation of nano iron oxide due to its simplicity, ease of preparation, and purity, compared to other methods. Nano iron oxide was made using a substance that causes precipitation and a coating from the alcoholic extract of orange leaves from Iraq. It was examined structurally and spectrally using several techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, field-emission scanning microscopy (FESEM), energy-dispersive X-ray spectroscopy, and UV-Vis spectroscopy. The diagnosis proved that the nano iron oxide was successfully prepared in a spherical form and with an average size of 71.1 nm. The nano iron oxide particles were tested for their ability to remove crystal violet (CV) dye from an aqueous solution using the adsorption technique, achieving a removal percentage of 51% at 298K, with an adsorbent dose of 0.01 g, a contact time of 90 minutes, and an initial dye concentration of 11 mg/L. The adsorption process data were analyzed kinetically using kinetic models. It was found that the process follows the pseudo-second-order kinetic model, suggesting that the type of adsorption is chemical. The results indicate the potential use of nano iron oxide to protect the aquatic environment.