Sulfidation of air-stable iron nanoparticles: A novel strategy how to boost their reactivity demonstrated on Cr(VI) reduction

Sulfidated zero-valent iron nanoparticles (S-nZVI) have been extensively studied as environmentally promising alternative material, which enables reduction of variety of extremely dangerous pollutants directly in the environment. However, synthesis and manipulation with these extremely reactive/pyrophoric nZVI particles represents a challenge and requires special precautions. In this study, we report a synthesis of S-nZVI from air-stable core-shell nZVI, which reactivity with contaminants and properties are comparable with the commonly prepared S-nZVI particles (where the precursor was bare/pyrophoric nZVI particles). The undeniable novelty dwells in the simplicity of the synthetic process, which ensures consequential safe and easy handling, manipulation, and application of S-nZVI particles. This material, especially highly effective against halogenated organic compounds and heavy metals, was characterized in detail and its advanced characteristics were evaluated in the process of hexavalent chromium (Cr(VI)) reduction from model aqueous solutions and polluted groundwater. The results offer valuable insights into the preparation of a novel nanomaterial with high application potential in the effective degradation of heavy metals in polluted water. Overall, the novel way prepared S-nZVI particles, designed for the potential large-scale production, eliminates the drawbacks of S-nZVI synthesized from bare nZVI particles and offers the effective material suitable for any on-site application. • New synthetic approach to production of S-nZVI particles with high reactivity • The advantages are safe handling, on-site and large-scale production • The S-nZVI particles are highly effective in reduction/elimination of Cr(VI) • Adsorption, reduction and precipitation dominate during Cr(VI) immobilization • The reactivity of proposed new S-nZVI compete with conventional (S-)nZVI