Nanoscale zerovalent iron (NZVI) for environmental decontamination:A brief history of 20 years of research and field-scale application

Environmental contamination continues to pose a serious threat to human health and the ecosystem. Over the next several decades, remediation research and business will be actively restoring both legacy and newly spilled sites in many countries worldwide. This chapter critically reviews the 20-year progress (1997–2017) in nanoscale zerovalent iron (NZVI) research and development from laboratory testing to pilot- and field-scale demonstrations. Several major areas of NZVI research, including (1) NZVI synthesis and reactivity, (2) aggregation, (3) transport in porous media, (4) polymer modification including carboxymethyl cellulose (CMC), (5) toxicity, (6) sulfidation, and (7) use of electromagnetic fields to enhance remediation, are discussed. Additionally, we summarize important aspects of pilot- and field-scale NZVI applications from 27 peer-reviewed articles and credible reports including the types of contaminants and NZVI used; delivery techniques; injection concentration, rates, and durations; hydrogeological conditions of the sites; pre-operations (before NZVI application); unexpected phenomena (such as clogging) during or after NZVI application; and performance monitoring including the radius of influence, treatment efficiency, and rebound. Finally, this chapter links the past, present, and future of NZVI research and application to the remaining 15 chapters of this book