Study On Degrading Molasses Alcohol Wastewater By Pyrolusite And Simultaneously Leaching Of Manganese

Molasses alcohol wastewater is a high-concentration organic wastewater with many components, which is very difficult to treat, especially the removal of coloring matter's. As an environmental mineral material, pyrolusite has been received abroad attention on dye decolorization. The aim of this study is to degrade molasses alcohol wastewater and leach manganese from pyrolusite simultaneously through the oxidation-reduction reaction between the wastewater and pyrolusite.In this paper, manganese from pyrolusite was leached by sulphuric acid and molasses alcohol wastewater. The single factor experiment was carried out to investigate the effects of leaching temperature, leaching time, the concentration of H₂SO₄, the concentration of pyrolusite and the mass ratio of wastewater/pyrolusite on the leaching of manganese, the COD removing rate and the decoloring rate. The optimal conditions of two sect leaching processes were found to be the following: the concentration of H₂SO₄ 1.13 mol/L, the concentration of pyrolusite 100 g/L, the molasses alcohol wastewater COD 1.27×10⁴ mg/L, the leaching temperature 95℃, the leaching time 2h. Under the optimum leaching conditions, the manganese leaching recoveries achieved were up to 92.3%, the COD removing rate of the wastewater was 78.5%, and the decoloring rate was 98.2%, respectively.The leaching kinetics of manganese from pyrolusite by molasses alcohol wastewater was studied. After reaching 200rpm.min^-1, the stirring speed had little effect on the leaching rate. The leaching rate of manganese can be accelerated by increasing the leaching temperature and the initial concentration of molasses alcohol wastewater and H₂SO₄, and reducing the particle size. A shrinking core model was used to describe the leaching kinetics, and the overall kinetical equation was obtained. The leaching process was controlled by the diffusion through the solid film. The apparent action energy was calculated to be 60.6kJ/mol. The apparent reaction order of wastewater was 1.38, and that of H₂SO₄ was 0.30. The overall kinetical equation of the leaching process was:...