Dual-supported nanoscale zero-valent iron for As(III) contaminated groundwater remediation

Nanoscale zero-valent irons (nZVIs) are easy to agglomerate and deactivate, which limited the practical applications in the subsurface for in situ remediation of contaminated groundwater due to poor radius of influence. Here, we utilized the dual support effect of coupling surface-modified carbon black with a surfactant (carboxymethyl cellulose (CMC) or sodium dodecyl sulfate (SDS)) to manipulate the charge, electron, and geometric structure of the interface, the obtained Fe/CB/CMC (wt%=1:1:2) and Fe/CB/SDS (wt%=1:2:1) suspensions exhibited superior removal capacity toward As(III) with capacities of 80.7 and 90.7 mg g-1, respectively. In a clay medium, 25.2% and 18.0% of nZVIs in Fe/CB/CMC-1:1:2 and Fe/CB/SDS-1:2:1 can break through the column while approximately 100% are retained in bare nZVIs under the same conditions. In addition, input velocity and ionic strength demonstrate a positive correlation with the retention of nZVIs in the Fe/CB/CMC-112 and a slight impact on the deposition of nZVIs in the Fe/CB/SDS-121 due to the rheology and charge differences between CMC and SDS. This study demonstrates the feasibility of combining anionic surfactants and carbon supports to enhance the reactivity and mobility of nZVIs for in situ remediation.