## 5 Novel Magnetic Ferrite Nanoparticle Applications in Wastewater Treatment
### Magnetic Ferrite Nanoparticles for Photocatalytic Degradation of Wastewater Pollutants
Pesticides and pharmaceuticals are sustainable for a long time in the ecosystem, and there is a need for sustainable water treatment that contains these complex organic molecules. Conventional methods show significant drawbacks, e.g., sludge formation. Chemical oxidation and photodegradation methods exhibit significant importance for wastewater treatment [250]. Pharmaceuticals are frequently used to promote human, animal, and ecological health and control diseases. Antibiotics are among the most widely used medications because of their strong ability to combat dangerous bacteria and infections. Phenol and phenolic compounds are frequently utilized as raw materials in the production of pesticides and pharmaceuticals [251]. Ferrite nanoparticles and their composites have been employed as photocatalysts for the degradation of different kinds of organic materials, e.g., dyes and pharmaceuticals [252]. [PERSON] et al. used ferrite nanoparticles to decorate graphene oxide (GO). A GO-CoFe\({}_{2}\)O\({}_{4}\) composite was deployed for the photodegradation of acetamiprid (an insecticide) and achieved 97% degradation efficiency under controlled conditions [253]. [PERSON] et al. synthesized copper-doped a cadmium aluminum ferrite (Cu\({}_{x}\)Cd\({}_{1-x}\)A\({}_{02}\)Fe\({}_{1.8}\)O\({}_{4}\) (x = 0, 0.2)) photocatalyst for the photodegradation of triazophos (a pesticide) and observed a reasonable increase in triazophos degradation within 100 min under 100 W visible irradiation; these doped ferrite nanoparticles exhibited 91.21% efficiency as compared to an undoped control photocatalyst. Cu-doped ferrite nanoparticles show improved  
Figure 12: CoFe\({}_{2}\)O\({}_{4}\)-based visible light photocatalyst mechanism for decomposition of organic pollutants. Reproduced with permission from Ref. [252]. light absorption, charge carrier separation, and a greater surface area; hence, they exhibit increased photocatalytic activity [254]  
Continuous efforts have been made to develop optimized magnetic ferrite nanoparticle-based photocatalysts. This is because different types of magnetic ferrite nanoparticles show different photocatalytic activities for different contaminants, so it is challenging to fabricate high-efficiency ferrite-based photocatalysts that should be low-cost, effectively applicable, and efficient photocatalysts for large-scale applications. Such a photocatalyst based on magnetic ferrite nanoparticles has yet to be demonstrated. Combining these characteristics in a single nanomaterial simultaneously is a challenging task. Therefore, in the past years, modified nanomaterials, doped magnetic ferrite nanoparticles, and composites with suitable additives have been studied as promising candidates for working as suitable photocatalysts for mitigating different contaminants in wastewater. Recently, the combination of magnetic ferrite nanoparticles with carbon allotropes, metal oxides, metal nanoparticles, polymeric materials, and other compounds has been investigated actively. Summaries of the methods described are provided in Table 2.