## 6 Conclusions and Future Perspectives  
Nanosized magnetic ferrite nanoparticles such as CoFe\({}_{2}\)O\({}_{4}\), MnFe\({}_{2}\)O\({}_{4}\), ZnFe\({}_{2}\)O\({}_{4}\), NiFe\({}_{2}\)O\({}_{4}\), and CuFe\({}_{2}\)O\({}_{4}\) have received impressive attention in the last decade due to their properties and practical applications in many fields, including wastewater treatment. Cobalt ferrite especially shows promising results in its application in visible light photocatalysis, a field which is developing fast nowadays. The exponential application growth created a demand for large-scale synthesis methods for ferrite nanoparticles with desired properties. However, some challenges remain to be solved before the broad commercial application of this type of particle in everyday life. One of the primary challenges is the synthesis of ferrite nanoparticles of a uniform size and high surface area. These factors are crucial for maximizing adsorption efficiency, yet controlling them during large-scale production remains difficult. Additionally, the stability of nanoparticles in diverse wastewater environments poses a problem, as factors like pH, temperature, and the presence of competing ions can impact their performance. Agglomeration of ferrite nanoparticles in water also reduces their surface area, making it difficult to maintain high adsorption rates. Another challenge is the regeneration and reuse of ferrite nanoparticles after pollutant removal. While their \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Ferrite Photocatalyst** & **Crystal** & **Synthesis** & **Metal Ions** & **Removal \%** & **Conditions** & **Ref.** \\ \hline \multirow{2}{*}{\begin{tabular}{c} Diocal \\ \end{tabular} } & Octahedral & \multirow{2}{*}{\begin{tabular}{c} Copperipitation \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} Ni(II) \\ \end{tabular} } & 97\%, 80\% & 60 min exposure at RT & [269] \\  & Octahedral & & & & NA & 10–140 min contact & [265] \\ CoFe\({}_{2}\)O\({}_{4}\) & Cubic & & & Pb(II), Zn(II). & 96\%, 92\%, NA & 10–120 min contact & [266] \\  & & Flash & & & & \\ (Co\({}_{0.2}\)Zn\({}_{0.3}\))\({}_{0.3}\)\({}_{0.1}\)\({}_{0.1}\)Fe\({}_{2}\)O\({}_{4}\) & Cubic & auto-combustion & Pb(II) & 99\% & 10–60 min contact & [270] \\  & & method & & & & \\ Co\({}_{0.7}\)Ni\({}_{0.3}\)Fe\({}_{2}\)O\({}_{4}\) & Cubic & & & & & \\ MgFe\({}_{2}\)O\({}_{4}\) & Cubic & & & & & 25 \({}^{\circ}\)C for 12 h & [268] \\  & & & & & & \\ NiFe@BAL & Cubic & & & & & \\ Ag\({}_{0.5}\)Zn\({}_{0.5}\)Fe\({}_{2}\)O\({}_{4}\) & Cubic & & & & & \\ hybrid composite & & & & & & \\ \multirow{2}{*}{Activated carbon} & \multirow{2}{*}{Amorphous} & Thermal & & & & \\ decomposition & & & & & & \\ \multirow{2}{*}{\begin{tabular}{c} Zeolite-based Ag NPs \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} Tetrahedral \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} Hydothermal \\ treatment \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} Ioine & 94.85\% \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} - \\ - \\ - \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} [275] \\ \end{tabular} } \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparison of various nano materials used for photocatalytic wastewater treatment. magnetic properties allow for easy recovery, the desorption of contaminants without degrading the nanoparticles' performance over multiple cycles is still not fully optimized. Current industrial-scale treatment systems are not designed to accommodate nanomaterials, requiring significant modifications or entirely new systems. Despite the challenges, advances in nanotechnology and materials science are expected to address many of these challenges. Improved synthesis techniques could lead to more environmentally friendly and scalable production methods for ferrite nanoparticles. Additionally, surface modification of nanoparticles with functional groups may enhance their selectivity for specific pollutants, increasing treatment efficiency.