Nowadays, the act of releasing dyes and colored effluents into bodies of water poses a significant problem as it can lead to the formation of toxic and carcinogenic compounds, ultimately polluting the water [1]. Consequently, numerous techniques have been developed to address this issue. However, traditional methods like reverse chemical precipitation, ion exchange, adsorption, and filtration tend to be expensive and may inadvertently transfer dyes from primary pollutants to secondary pollutants, necessitating further treatment [2]. Among the available methods, the adsorption of dyes onto sorbents emerges as a cost-effective approach for removing pollutants. Its initial cost, simplicity, ease of operation, and sensitivity to toxic pollutants make it superior to alternative water re-use methods. Nonetheless, it is important to acknowledge that adsorption does transfer organic pollutants to secondary ones, which subsequently require additional treatment. Hence, researchers have made an important discovery a safe and environmentally friendly wastewater treatment method known as the photodegradation of dyes [3]. In this study, zinc-nickel ferrite magnetic nanoparticles were synthesized using the sol-gel method. The synthesized nanoparticles were characterized using various techniques including field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), dispersive X-ray analysis (EDX), Brunauer-Emmett-Teller (BET), Fourier transforms infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), and UV-Vis diffuse reflectance spectroscopy (DRS). The X-ray powder diffraction analysis confirmed the formation of cubic spinel phase nanoparticles. Furthermore, the photocatalytic activity of the magnetic nanoparticles was assessed by measuring the degradation of reactive blue 21 dye under visible light irradiation. The study also investigated the effects of various process parameters such as catalyst dosage, initial dye concentration, and visible light irradiation on the degradation of the dye.
