Experimental Study on the Removal of Fe2+ and Mn2+ from Zinc Sulfate Water by Micro-nano Ozonation

Abstract

In the production process of zinc sulfate, the presence of Fe and Mn had an adverse effect on the crystallization process of zinc sulfate production and reduce the purity of MgSO4·7H2O. Traditional chemical treatment methods are costly and easy to introduce new impurity ions. To obtain high-quality zinc sulfate, it is essential to develop a new Fe2+ and Mn2+ removal process. In this experiment, micro-nano bubble and ozone oxidation combined technology was used to explore the influence of different gas sources, temperature, CaCO3 dosage method and dosage on the oxidation effect of Fe2+ and Mn2+, and to analyze the feasibility of the technology in a practical production application. Results showed that the removal rate of Fe2+ and Mn2+ was more than 99.5% with ozone as the gas source, which was much higher than that with air and oxygen as the gas source. The increase of temperature had an effect on the stability of micro and nano bubbles and the solubility of ozone, which was not conducive to the oxidation of Fe2+ and Mn2+. The treatment time of Mn2+ at the maximum temperature of 18℃ was shortened by 12.5% compared with that at 24℃. The addition of CaCO3 significantly improved the removal efficiency of Fe2+ and Mn2+ by micro-nano ozone. When the relative dosage of 0.44 g/L CaCO3 was added every 15 min, the adequate total amount of CaCO3 was 17.6 g, and the complete Removal of Fe2+ and Mn2+ took about 50 min, which shortened the treatment time by 33% compared with the treatment time without CaCO3. Effect of intermittent dosing was better than that of one-time dosing, and the amount of CaCO3 consumed was more petite.

Keywords

• micro-nano bubble
• ozonation
• iron manganese removal
• calcium carbonate