Zero-valent iron-based technologies for removal of heavy metal(loid)s and organic pollutants from the aquatic environment: Recent advances and perspectives

Heavy metal(loid)s and organic pollutants have garnered global concern due to their potential for bioaccumulation and carcinogenic effects. The aquatic environment is one of the most important receiving compartments for these pollutants. Therefore, researchers are committed to developing inexpensive and highly efficient technologies for the removal of these recalcitrant contaminants from water. Zero-valent iron (ZVI), which has a strong reduction ability, low cost and can be recycled, has been considered as an environmentally benign element for removal of heavy metal(loid)s and organic chlorinated pollutants. However, some factors limit the ZVI application, with passivation of ZVI considered as the main limitation. Recent research has focused on methods to eliminate or alleviate these interferences and maximize ZVI performance. This review summarizes recent findings for the removal of typical heavy metal(loid)s and organic pollutants in the aquatic environment by ZVI-based technologies. Different combinations of chemical, physical, biological, or other methods with ZVI and their operating conditions and influencing factors are presented and discussed. Finally, we also present the removal mechanisms of ZVI-based technologies and recommendations for future research. This review provides an up-to-date perspective on the removal of pollutants using ZVI-based technologies and collates references for future large-scale application to wastewater treatment.