Influence of Humic Acid on Nanoscale Zerovalent Iron Reaction in Oxic Water: Structural Evolution, •OH Generation, and As(III) Sequestration

OH-mediated oxidation of As(III) to arsenate [As(V)] at pH 6.0, whereas at pH 9.0, it resulted in faster As(III) sequestration by generating new adsorption sites and enhancing As-Fe coprecipitation. These findings provide valuable insights into the roles of HA in modulating nZVI performance in environmental applications and As(III) fate.