Adsorption performance of antimony by modified iron powder

Antimony pollution resulting from industrial production is a great threat to the environment, ecology and the human body. Zero-valent iron powder is low-cost and easy to obtain. Nevertheless, the lower adsorption capacity limits its application when it is used as an adsorbent. In the present study, ball-milling and acid modification were developed to change its surface characteristics and γ-Fe₂O₃, γ-FeOOH and Fe₃O₄ were obtained after treatment, which promoted its adsorption capacity. Compared with the raw iron powder, the adsorption capacities for Sb(iii) and Sb(v) using the modified material were increased from 12.93 mg g^-1 and 5.47 mg g^-1 to 17.96 mg g^-1 and 10.58 mg g^-1, respectively. The study showed that the experimental data fitted the Langmuir model and the pseudo-first-order kinetic model better; the adsorption process was monolayer and chemically controlled at pH 5.0 ± 0.2. XPS and FT-IR analysis showed that Fe-O-Sb bonds arose during the adsorption process. The effect of pH on the adsorption capacity was also studied and the pH affected the adsorption of Sb(v) more than the adsorption of Sb(iii). In addition, the modified iron powder presented better efficiency when applied to the removal of low levels of antimony in drinking water. Based on the increase of adsorption capacity and low cost, iron powder should be a promising adsorbent for aqueous antimony removal.