## 5 Novel Magnetic Ferrite Nanoparticle Applications in Wastewater Treatment
### Magnetic Ferrite Nanoparticles' Application in Adsorption of Toxic Materials
studied alkaline metal-doped Ni ferrites via the coprecipitation method, and absorption studies were performed with varying parameters such as pH, concentration, contact time, etc. It was observed that doped Ni ferrites show high absorption rates for Pb(II) and Cd(II) at 97% and 80%, respectively, as compared to undoped Ni ferrites at 83% and 45%, respectively [29]. Similarly, [PERSON] et al. synthesized hydrolyzed Luffa Cylindrica (HLC)-based CoFe\({}_{2}\)O\({}_{4}\) via the coprecipitation method. Ni(II)-based heavy metal removal studies were observed at room temperature at pH = 6, with a contact time of 60 min. It was observed that there was 99.13% Ni(II) ion removal from wastewater at 44.42 mg/g, and after eight cycles, no significant decrease occurred in the adsorption efficiency [265]. In a study, [PERSON] et al. showed the versatile adsorption potential of cobalt-based magnetic ferrite nanoparticles to adsorb heavy metals and dyes from wastewater. The synthesized cobalt ferrite nanoparticles via the coprecipitation method showed effective absorbance of lead, zinc, Congo red, and malachite green in monolayer adsorption capacities of 275, 390, 831, and 161 mg/g, respectively. The dynamic behavior of Co-based ferrite was validated via modeling [266]. In another study, [PERSON] et al. synthesized (Co\({}_{0.7}\)Zn\({}_{0.3}\))\({}_{0.9}\)Ni\({}_{0.1}\)Fe\({}_{2}\)O\({}_{4}\) ferrite and used it for the removal of Pb (II) ions from wastewater by exploring a medium pH and the contact time. It was observed that the current system performed well at pH 7 after 40 min of contact time [20]. [PERSON] et al. synthesized Co\({}_{0.7}\)Ni\({}_{0.3}\)Fe\({}_{2}\)O\({}_{4}\) spinel nano ferrites via the coprecipitation method and obtained a nanoparticle powder after post-annealing at 700 \({}^{\circ}\)C for 1 h. The effective adsorption of 99.9% Cr(III) ions from waste was observed for a contact  
Figure 13: Ferrite nanoparticle applications as adsorbents for metal ions’ removal. Reproduced with permission from Ref. [263]. time of 30 min [267]. Mg-based ferrites show exceptional chemical and thermal stability, offering many active sites at the surface and high surface area. In this respect, [PERSON] et al. synthesized magnesium ferrites (MgFe\({}_{2}\)O\({}_{4}\)) via a one-step solvothermal method and applied the removal of arsenic ions from water as a function of various Mg and Fe ratios. Variations in Mg:Fe ratios affect nanoparticles' physical and magnetic properties. The observed best As(III) and As(V) absorbances at room temperature on pH = 7 via an Mg:Fe ratio of 33:67 were 103.5 mg/mL and 45.52 mg/mL, respectively [268]. Although magnetic ferrite nanoparticles show their potential as a cost-effective and versatile adsorbent material for pollutants that are adsorbent from wastewater, there has not been enough research to make them suitable adsorbent sites for multiple pollutants. It is essential to overcome the current challenges that restrict using magnetic ferrite nanoparticles for wastewater treatment. Catalyst recovery, cost-effectiveness, and the creation of reliable reactor designs are some of the most crucial challenges. The detailed summaries of the described synthesis methods can be found in Table 3.