Heavy metal contamination in industrial effluents presents a serious threat to the environment and human health because of their toxicity, non-biodegradability, carcinogenicity, and bioaccumulation in living organisms. Recently, the preparation and application of iron oxides, especially magnetite nanoparticles, for metals removal have been investigated due to their nano size, magnetic separation, and the ease of synthesis, coating, and modification. However, magnetic nanoparticles lose some magnetization due to air oxidation. Magnetite nanoparticles coating with inorganic shell, like silica and carbon, have been reported and were capable of improving chemical stability. The effects of pH, contact time, and initial concentrations on the removal of heavy metals should be studied using nano-composites in water. In this chapter, the authors present a technical review on different nano-composites used for bioremediation and their limitations.
