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

The soil in primary explosives sites have been contaminated by high concentrations of antimony(Sb) and co-occurring heavy metals (Cu and Zn), but which is largely overlooked and neglected. In this study, we investigated the concentrations and species of Sb and studied the effect of Fe based, Fe-Al based sorbents combined application on the mobility of Sb and co-occurring metals. The content of Sb in soil samples was from 26.7 to 4255.0 mg/kg, occurring predominantly as Sb(V) (65.57 ~ 95.46%). In batch experiments, FeSO 4 showed ideal sorption of Sb (up to 97% sorption with 10% FeSO 4 ·7H 2 O), while sorption rates 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 in varying levels, especially FeSO 4 ·7H 2 O. Al(OH) 3 was necessary to prevent mobilization of Cu and Zn. In this study, 5% FeSO 4 ·7H 2 O and 4% Al(OH) 3 mixed with soil was the optimal choice to solve this problem with stabilization effect of Sb, Zn, Cu being 94.6%、74.2% and 82.2% respectively. Column tests spiked with 5% FeSO 4 ·7H 2 O and 4% Al(OH) 3 showed significant retention of Sb (85.85%), Zn (83.9%), Cu (94.8%). pH regulated results indicated that acid condition was more beneficial for retention of Sb than alkaline condition. However, there was no significant difference between sets of acidification and sets without pH regulation. Overall, the experimental results showed that 5% FeSO 4 ·7H 2 O + 4% Al(OH) 3 without pH regulation could be effective for the stabilization of Sb and co-occurring metals in primary explosives soils.