Recent Advances and Challenges in Nano Zero-Valent Iron and Its Composites for Arsenic Removal from Wastewater: Synthesis Strategies, Modification Approaches, and Removal Mechanisms

Abstract

Arsenic contamination poses a severe threat to global aquatic ecosystems and human health, necessitating effective remediation strategies. Nano zero-valent iron (nZVI) has emerged as a promising material for arsenic removal due to its high surface area, excellent reduction capacity, and unique core-shell structure. However, its practical application is hindered by inherent limitations such as particle agglomeration, surface passivation, and oxidative deactivation. This review systematically examines recent advances in nZVI and its composites for inorganic arsenic removal from wastewater. First, we summarize nZVI synthesis methods, including physical and chemical approaches, highlighting the potential of green in situ synthesis for sustainable groundwater remediation. Next, we critically analyze key modification strategies for nZVI, including bimetallic modification, sulfidation modification, surfactant modification, and solid-loading modification, and emphasize the shift from single modifications to synergistic multifunctional designs. Furthermore, we evaluate the influence of environmental factors, including pH, coexisting ions, adsorbent dosage, and reaction time, on arsenic removal efficiency. The underlying mechanisms—primarily adsorption, oxidation, and coprecipitation—are thoroughly discussed. Finally, we identify current challenges and future research directions for nZVI-based materials in global applications. This review provides valuable insights for designing eco-friendly, cost-effective, and high-performance arsenic removal technologies.