Due to the increased demand for clothes by the growing population, the dye-based sectors have seen fast growth in the recent decade and also the industrial waste water. This waste water contains heavy metals such as cadmium, mercury which raises the stakes for the environment. The numerous sources of heavy metal in wastewater and their effective treatment procedures are addressed in the current review. Even among nanoparticles, photocatalytic materials, such as TiO2, ZnO, and Fe3O4 have shown greater potential for photocatalytic degradation of heavy metals such as cadmium and mercury. Such nano-sized metal oxides are the most ideal materials for the removal of water pollutants, as these materials are related to the qualities of flexibility, simplicity, efficiency, versatility, and high surface reactivity. The use of nanoparticles generated from waste materials to remediate heavy metals is highlighted in the present research.