Review on nano zerovalent iron (nZVI): From synthesis to environmental applications

For remediation of water and soil, various nanoparticles such as zeolites, metal oxides, carbon materials, metals, or bimetallic nanoparticles (e.g. Fe/Pd, Fe/Ag) have been reported. However, the most extensively applied nanoparticle is nano zerovalent iron (nZVI). It is due to properties and effectiveness of nZVI in the removal of pollutants as well as its cost effectiveness of production. The aim of this work is to present the opportunities and risks arising from the use nZVI from its synthesis to environmental application. Compared to the previous reviews, our paper shows, a new look on nZVI with the common (e.g. milling, chemical reduction) and the latest methods of synthesis (e.g. green synthesis, ultrasound or electrochemical method) and modification of nZVI, whose number is increasing especially in recent years. Therefore, refer to the new trends is very important when selecting nZVI for the treatment of various matrices. This review also identifies problems that may occurs a result of changes in the physicochemical properties of nZVI due to their modification (e.g. other metal doping, coating the surface, or deposition on the support). Research shows that modifications of the nZVI surface can help in their stabilization, reduction of aggregation, and reduction of toxicity. However, the improvement of those properties may simultaneously lead to the creation of other threats related with the application of nZVI. Finally, we present the latest examples of practical utilization of nZVI for the remediation of soil and water in large-scale application. Research demonstrates that nZVI can be an effective and versatile tool for the purification of different matrix and especially groundwater.