From nZVI to SNCs: development of a better material for pollutant removal in water

Nanoscale zero-valent iron (nZVI), with its reductive potentials and wide availability, offers degradative remediation for environmental pollutants. However, weaknesses such as easy aggregation, easy oxidation, and nanoscale size have hindered its further applications in the environment to some extent. Therefore, various supported nZVI composites (SNCs) with higher dispersibility, enhanced water stability, and tunable size have been developed to overcome the weaknesses. SNCs family is a great alternative for water purification applications that require high removal efficiency and rapid kinetics, as a result of their multifunctional properties and magnetic separation capacity. In this review, we compare the advantages of SNCs to nZVI for pollutant removal in water, discuss for the first time the synthetic techniques of obtaining SNCs, and analyze the influencing factors and mechanisms associated with the removal of some typical hazardous pollutants (e.g., dyes, heavy metals, nitrogen, and phosphorus) using SNCs. Moreover, limitations and future research needs of such material are discussed. More attention should be paid to the evaluation of toxicity, development of green synthetic routes, and potential application areas of such materials in future research.