Abstract
Nanoscale zerovalent iron (nZVI)-based materials are widely utilized for remediation of heavy metal-contaminated groundwater. However, the physicochemical transformations of nZVI-heavy metal (nZVI-HM) reaction products and the dynamic changes of heavy metals in groundwater environments remain insufficiently understood. Herein, this work investigates the long-term transformation of nZVI, sulfurized nZVI (S-nZVI), and carboxymethyl cellulose (CMC) modified nZVI during remediation processes using Pb and Zn as representative pollutants, along with their potential for heavy metals release under varying environmental conditions. Results indicate that over a two-month period, all three materials exhibited excellent pollutant removal capabilities across various aquatic environments. The structural evolution and composition of nZVI-HM hybrids are influenced by groundwater constituents, reaction duration, and nanomaterial type. The ability of these nanomaterials to sequester Pb/Zn is largely unaffected by humic acid but is sensitive to pH fluctuations. A sudden drop in environmental pH can lead to the release of adsorbed Zn2+ . Notably, modified materials, particularly S-nZVI, demonstrate enhanced tolerance to acidic conditions. Nevertheless, with prolonged aging time, the dissolved Zn2+ could be re-stabilized by the material. These findings offer a scientific basis for assessing the long-term efficacy and potential environmental risks associated with different types of nZVI in groundwater heavy metal remediation.
