The Chemical Oxidation and Immobilization of Arsenic and Antimony in Simulated AMD in Karst Areas.

The widely distributed carbonate rock in karst areas can neutralize AMD, increase pH and promote Fe(II) oxidation, which produce reactive oxidation species (ROS) and iron (hydr)oxides. (ROS) and iron (hydr)oxides can facilitate oxidation and immobilization of As and Sb. The flow, pH and Fe(II) concentration of AMD may affect oxidation or immobilization of As/Sb via affecting of Fe(II) oxidation in AMD. This study investigated the influence of Fe(II) oxidation on the transfer and transformation of As/Sb in simulated AMD induced by carbonate. Low flow and high pH were beneficial for Fe(II) oxidation to produce ROS/Fe(IV) and iron (hydr)oxides to oxidize As(III)/Sb(III). Fe(II) concentration (100-500 mg/L) had negligible influence on oxidation and sediment of As(III)/Sb(III). With increase of reaction time, difference in As(III)/Sb(III), total As/Sb concentrations between different flow distances were decreasing.