Nano zero-valent iron-based technology for environmental remediation: Synthesis techniques and strategies to address limitations

Abstract

Nano zero-valent iron (nZVI) is a promising technology for the remediation of both organic and inorganic pollutants in groundwater and wastewater. Despite its potential, there are several limitations of as-prepared nZVI particles, including surface passivation, agglomeration, reduced mobility, and reactivity in subsurface environments, as well as pH sensitivity. This comprehensive review aims to address these limitations by evaluating different nZVI production techniques in terms of their intrinsic properties, such as particle size and surface area, and their implications. Furthermore, practical limitations associated with as-prepared nZVI particles are described, and potential countermeasures are discussed. These countermeasures include pretreatment methods such as acid washing, hydrogen gas, liquid nitrogen activation, and coupling with weak magnetic force, as well as surface modification methods such as metal coupling, sulfidation, polymer, surfactant, and cellulose coating, emulsification, and support with other adsorbent materials. The review also provides examples of pilot-scale and field-scale applications of nZVI particles. Overall, the review offers a comprehensive overview of nZVI synthesis methods and their implications for production processes. The strategies presented for improving the reactivity and performance of nZVI particles in practical applications are valuable for researchers and practitioners in the field of environmental remediation.