An innovative method to enhance manganese and ammonia nitrogen leaching from electrolytic manganese residue by surfactant and anode iron plate

Abstract Electrolytic manganese residue (EMR) contains a lot of manganese (Mn2+) and ammonia nitrogen (NH4+-N), which can cause environmental pollution. In this study, surfactant and anode iron plate were used to synergistically enhance NH4+-N and Mn2+ leaching from EMR. The Characteristics of EMR, Mn2+ and NH4+-N leaching mechanism, and the leaching test were systematically studied. The results showed that the leaching efficiencies of Mn2+ and NH4+-N were 89.4% and 65.9%, respectively, when the current density was 20 mA/cm2 and iron as the anode plate, the mass of H2SO4 was 13 wt%, solid-to-liquid ratio of 1:5 at 20 °C reacting for 120 min. In addition, when the surfactant concentration of tetradecyl trimethylammonium chloride (TTC) was 100 mg/L, the leaching efficiency of Mn2+ and NH4+-N in EMR respectively increased from 89.4% to 97.1% and from 65.9% to 98.4% by adding electric field. The leaching efficiencies of Mn2+ and NH4+-N were 28.5% and 93.7%, respectively, which was higher than that attained under the same condition without an electric field and TTC surfactant. Meanwhile, electric field changed the movement and charge distribution of charged particles on the surface of SiO2 and CaSO4·2H2O particles and released soluble compound salt containing Mn2+ and NH4+-N. TTC surfactant also improved the hydrophilic and hydrophobic properties of the EMR surface and promoted the wetting ability of the particles and the leaching of Mn2+ and NH4+-N. This study shows that TTC surfactant and anode iron plate can enhance NH4+-N and Mn2+leaching from EMR.