Wet milling-induced defects in microscale zerovalent iron significantly enhance its performance for metal(loid) sequestration

The modification of lattice structure holds promise to impart excellent performance to zerovalent iron (ZVI) while facing limitations in large-scale manufacturing and technical challenges related to additives. Here, a scalable and additive-free method, wet milling, is employed to modify ZVI by introducing lattice defects. Density functional theory analysis suggests defects can enhance reactivity by providing an electronic structure favorable for adsorption and electron transfer to the adsorbed metal(loid)s. Vacancy-type defects were induced in ZVI by milling in a liquid medium, confirmed by systematic characterizations including positron annihilation lifetime spectra. Compared to ethanediol medium, milling in water causes more Fe(0) loss in ZVI but requires shorter milling time for optimal performance. Wet-milled ZVI exhibits large removal rate constants that are up to 4836 times greater than pristine ZVI, achieving 96% Se(VI) removal in 10 s, and its specific removal capacity is also higher (4.58-fold) than pristine ZVI. Additionally, wet milling significantly improves the removal rates of a wide range of metal(loid)s by ZVI and effectively reduces costs, suggesting its great potential for metal(loid) wastewater treatment. Therefore, this study presents a novel ZVI lattice modification method for rapid and high-capacity decontamination and may also inspire new modification strategies for metal materials.