Antimony Immobilization in Primary-Explosives-Contaminated Soils by Fe-Al-Based Amendments

Soils at primary explosives sites have been contaminated by high concentrations of antimony (Sb) and co-occurring heavy metals (Cu and Zn), and are largely overlooked and neglected. In this study, we investigated Sb concentrations and species and studied the effect of combined Fe- and Fe-Al-based sorbent application on the mobility of Sb and co-occurring metals. The content of Sb in soil samples varied from 26.7 to 4255.0 mg/kg. In batch experiments, FeSO4 showed ideal Sb sorption (up to 97% sorption with 10% FeSO4 center dot 7H(2)O), whereas the sorptions of 10% Fe-0 and 10% goethite were 72% and 41%, respectively. However, Fe-based sorbents enhanced the mobility of co-occurring Cu and Zn to varying levels, especially FeSO4 center dot 7H(2)O. Al(OH)(3) was required to prevent Cu and Zn mobilization. In this study, 5% FeSO4 center dot 7H(2)O and 4% Al(OH)(3) mixed with soil was the optimal combination to solve this problem, with Sb, Zn, and Cu stabilizations of 94.6%, 74.2%, and 82.2%, respectively. Column tests spiked with 5% FeSO4 center dot 7H(2)O, and 4% Al(OH)(3) showed significant Sb (85.85%), Zn (83.9%), and Cu (94.8%) retention. The pH-regulated results indicated that acid conditioning improved Sb retention under alkaline conditions. However, no significant difference was found between the acidification sets and those without pH regulation. The experimental results showed that 5% FeSO4 center dot 7H(2)O + 4% Al(OH)(3) without pH regulation was effective for the stabilization of Sb and co-occurring metals in primary explosive soils.