An Effective Method to Remove Antimony in Water by Using Iron-Based Coagulants

The effectiveness of antimony (Sb) removal by using iron-based coagulants was investigated in this study. The effects of pH, coagulant types and dose, equilibrium concentration, co-existing humic acid (HA) and anions, and oxidation process were studied. Effective Sb removal was achieved by using Fe(III)-based coagulants. However, the removal efficiency of Sb by using Fe(II)-based coagulants was very low. The removal capacity of Sb fitted the Sips adsorption isotherm well, which revealed that the heterogeneous adsorption process onto the formed hydrous ferric oxide played an important role in Sb removal, and the mechanism was further supported by Fourier transform infrared spectrum analysis. Sb removal was inhibited by the presence of HA and phosphate, as well as oxidation and aeration. Therefore, coagulation by using Fe(III)-based coagulants without oxidation is an effective and promising method for removing Sb in aqueous solution.