Removal of reactive blue RB238 azo dye by Ni-Cu nanoparticles produced using eucalyptus leaf extract

Abstract

This paper aims to develop an effective method for removing organic dye from polluted water by adsorption using nanoparticles prepared from eucalyptus leaf extract. Synthetic dyes, particularly azo dyes, have attracted significant attention due to their toxic and harmful impacts on human health and the environment. In this context, an eco-friendly green synthesis method utilizing eucalyptus leaf extract was employed to prepare nickel-copper nanoparticles (Ni-Cu NPs). The nanoparticles were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and scanning electron microscopy (SEM). AFM images showed that the nanoparticle sizes ranged from 10 to 40 nm in great abundance. These results are in agreement with the calculations made using the Debye-Scherrer equation, where the crystallite size of the three main peaks was found to be (32, 19, 21) nm. The removal of Reactive Blue 238 dye (RB238) using nanoparticles was investigated. The dye removal effectiveness was found to be dependent on the initial pH (3.5-9) and temperature (293-313K), as well as the concentration of Eucalyptus nickel and copper nanoparticles, or (E-Ni-Cu/NPs) (0.5-2.5 g.L^-1) and dye (25-100 mg.L^-1). With an appropriate adsorbent concentration of 0.1 g per 25 mg.L^-1 and an acidic medium with a pH of 3.5, it was found that 293K would produce the best decolourization of 100% in 45 minutes. The results of the kinetic adsorption models indicate a pseudo-second-order model.