The application of nano Fe3O4 particles and their modified products in the field of environmental protection is mainly as a magnetic adsorbent to purify water. In the process of water treatment, adsorption technology has received widespread attention due to its advantages of simple operation, low cost and high efficiency. Surface-modified magnetic nanoparticles have the characteristics of large specific surface area, strong adsorption capacity, easy separation, and recyclability, and have very broad application prospects in environmental purification.
With the development of modern industry, the problem of heavy metal pollution in water environment is becoming more and more serious. Heavy metal pollutants in water are mainly Pb2+, Hg2+, Cr6+, Cd2+, Cu2+, Co3+, Mn2+ and so on. Heavy metal ions have obvious toxicity even at very low concentrations, enter water, soil and atmosphere, causing environmental pollution; they can also enter the human body through the food chain through bioconcentration, which seriously threatens human health.
Magnetic separation technology to treat sewage has advantages that other technologies cannot match, and it has played a great role in the adsorption of heavy metals.

Above for your reference only, detailed application would needs your own testing, thanks.