Boosting the activity and environmental stability of nanoscale zero-valent iron by montmorillonite supporting and sulfidation treatment

Abstract

Given its high activity and nontoxicity, nanoscale zero-valent iron (nZVI) has been intensively used to remediate the groundwater contaminated by trichloroethylene (TCE). However, the long-term stability of nZVI could be impaired by aging and natural organic matter. Herein, a montmorillonite-supported sulfurated nZVI (S-nZVI/MMT) was successfully synthesized, which exhibited robust activity and stability under environmental conditions through the interlayer interaction of MMT. The removal efficiency of TCE by S-nZVI/MMT reached 78.7%, which was much higher than that by S-nZVI and nZVI/MMT, within 12 h with Fe/S dosage ratio of 1:1 and particle dosage of 4 g/L. Importantly, the presence of high concentration of humic acid (up to 50 mg/L) caused unobvious effect on the performance of S-nZVI/MMT toward TCE removal, and more than 68.1% of removal efficiency of TCE could be maintained when the particle was aged in water for 30 days. The high activity and stability of S-nZVI/MMT may be attributed to the formation of nano-sized S-nZVI clusters in the MMT interlayer, protecting the active sites from passivation of humic acid. This work may promote the application of nZVI under complex natural conditions.