Immobilization and transformation of co-existing arsenic and antimony in highly contaminated sediment by nano zero-valent iron

摘要

Arsenic(As)and antimony(Sb)are usually coexistent in mine wastes and pose a great threat to human health.The As immobilization by nano zero-valent iron(n ZVI)is promising,however,the stabilization for co-occurring As and Sb is not known.Herein,the immobilization and transformation of As and Sb in n ZVI-treated sediments were evaluated using complementary leaching experiments and characterization techniques.Raw sediment samples from a gold-antimony deposit revealed the co-existence of ultrahigh As and Sb at 50.3 and 14.9 g/kg,respectively.Leaching results show that As was more efficiently stabilized by n ZVI than Sb,which was primarily due to the soluble fraction that was readily absorbed by n ZVI of As was higher.As the n ZVI treatment proceeds,the oxidation and reduction of As and Sb occur simultaneously as evidenced by XPS analysis.The primary oxidant,hydroxyl radicals,was detected by EPR studies,proving the occurrence of n ZVI induced Fenton reaction.This study sheds light on differences in the interaction and immobilization of n ZVI with Sb and As in co-contaminated sediments.