The overlooked role of carbonaceous supports in enhancing arsenite oxidation and removal by nZVI: Surface area versus electrochemical property

Carbonaceous supports (e.g. biochar) have been widely applied to enhance the performance of nanoscale zero-valent iron (nZVI) for removing heavy metals arsenic; As) due their large surface areas (SSA) alleviate nZVI particles aggregation, while electrochemical properties are largely overlooked. Herein, role these two characteristics in enhancing As(III) removal has systematically investigated through designing parallel experiments identify effects biochar. Our results suggest that biochar with varying (33.38–470.36 m2/g) supported exhibits a substantially higher oxidation rate (29.7–34.3%) and [295.5–371.5 mg/(g·nZVI)] efficiency compared by [27.1%; 192.7 mg/(g·nZVI)]. Despite importance SSA, extremely low SSA 33.38 m2/g appears comparable capacity nZVI’s loading up 50%. On contrary, analysis suggests highly related electron accepting biochar, indicating strong effect pyrolysis temperature. Surface quinone moieties found responsible transfer between [up 0.25 mmol e·(g biochar)−1] nZVI, promoting corrosion generation reactive oxygen species (ROS; mainly ·O2-) removal. These findings highlight important carbonaceous rather than developing nZVI-based materials further improving