**4. Conclusion and outlook**

It can be seen from the summarized statements that using "green" agents to fabricate materials is a possible route. However, many studies have shown that the efficiency in both the reaction yield and the properties of the obtained MNPs is very impressive, the plant source is immense, and scientists still need to do more research to improve the effectiveness and activity of MNPs products.

The results show that integrating a sufficiently large amount of Fe3O4 will make the composites magnetic enough to separate them from the aqueous solution by an external magnetic field. This characteristic is significant, overcoming the inherent disadvantage of nanomaterials which disperse too well to be challenging to recover. Since then, this defect has been resolved smoothly. Recent studies have also considered the applicable conditions closer to reality when the effects of cations, anions, and natural organic matter (NOM) are thoroughly investigated and evaluated. In addition, with many contaminants such as arsenic, and several organic pollutants,

ferromagnetic oxide not only acts as a recovery aid but also enhances the treatment efficiency thanks to its unique properties. The summarized research results also show an excellent combination between a magnetic metal oxide and a semiconductor metal oxide, which plays a crucial catalytic role in the photodegradation of pollutant compounds, especially organic pollutants. Some studies have shown the mechanism of the entire treatment process, including the adsorption of pollutants on the material's surface and the photodegradation reaction taking place at the catalytic sites under the catalysis activation of UV radiation or visible light.
