Abstract:Applying blast furnace slag, steel slag, desulfurization gypsum and calcium hydroxide as main raw materials, iron-containing amendments were prepared by further adding iron sulfate. The passivation of As and Sb in co-contaminated soil was investigated by using iron-containing amendments. The passivation mechanisms were revealed by investigating the changes of As, Sb and Fe fractions, mineral compositions of soil and chemical states of As and Sb. The results show that the leaching concentrations of As and Sb can be significantly reduced from 69.7 and 172.67 μg/L to 6.95 and 1.61 μg/L respectively, while the dosage of iron-containing amendments with 15% FeSO4 is 20% and H2O2 solution with 2% concentration is used to replace pure water. After passivation, the nonspecifically absorbed As and Sb reduce by 7.3% and 11.7% respectively, and the specifically absorbed As and Sb reduce by 2.7% and 0.9% respectively. Available As and Sb are transformed to Fe/Al hydrous oxide-bound and residual As and Sb species. New phases of goethite and ferrihydrite are generated in passivated soils, and the contents of amorphous/crystal Fe oxides in soils rise remarkably after passivation. Besides, some As(Ⅲ) species are transformed to As(Ⅴ). The results reveal that Fe-As, Fe-Sb and Ca-Sb species might be generated after As and Sb in soil are passivated by iron-containing amendments.