Enhanced Treatment\nof Antimony Mine Wastewater by\nSulfidated Micro Zerovalent Iron (S-mZVI)

Commercial\nmicron zerovalent iron (mZVI) and sulfur were used to\nprepare sulfidated micro zerovalent iron (S-mZVI) through ball milling.\nThe corrosion potentials of mZVI and S-mZVI were −0.01 and\n−0.37 V, respectively, indicating S-mZVI possessed a stronger\nelectron-donating ability. The practical antimony mine wastewater\n(<i>C</i><sub>0(Sb(V))</sub> = 3.8296 mg/L, pH = 8.29) was\ntreated. If meeting the national discharge standard of 5 μg/L,\n2.0 g/L mZVI and 1.6 g/L S-mZVI were required within 120 min. Passing\nN<sub>2</sub> or reducing wastewater pH enhanced the treatment of\nSb(V) by S-mZVI, in which the wastewater acidification was more effective.\nOnce the wastewater pH was adjusted to 3.00, only 0.7 g/L S-mZVI and\n40 min long time were needed to achieve the emission below 5 μg/L.\nEven S-mZVI underwent four cycles, and the final concentration of\nSb(V) was as low as 4.67 μg/L. As the pH<sub>zpc</sub> value\nwas 4.09 and the corrosion potential was −0.56 V at pH 3.0,\nthe electron-donating ability of S-mZVI as well as the electrostatic\nattraction between the surface of S-mZVI and Sb(V) increased. Sulfidation\nof mZVI and then application under the acid condition significantly\nimproved the treatment efficiency of Sb(V).