Indigo Carmine Removal By The Biogenic Mn Oxides And Active Carbon Doped With Mn Oxides

Indigo carminre is a dye which has a long history and high toxicity. Waste containting IC from industrial textile, paper and plastic industries has caused serious pollution to the environment. Therefore, green and efficient removal ways of IC has the vital significance in the environmental protection work.The biogenic Mn oxides are produced by Mn(Ⅱ) oxidation of manganese oxide bacteria, which has a strong adsorption and oxidation ability for a variety of material. This research has found that deep-sea manganese oxide bacteria Marinobacter sp. MnI7-9 in 10 mM Mn (II) can remove 90.24% of 45.45 mg/l IC. The specific surface area and bore diameter of the biogenic Mn oxides produced by Marinobacter sp. MnI7-9 is 27.68 m2/g and 1.55 nm, respectively. The IC removal by the biogenic Mn oxides contains degradation and adsorption, while adsorption is chief and the equilibrium time was about 45 h; the removal process was fit for pseudo-first-order kinetics for 5 mg L"1 IC and fit for pseudo-second-order kinetics for 20 mg L"1 IC; intra-particle diffusion was the sole rate-controlling step. The amount of IC removal was increased with increasing the amount of the biogenic Mn oxides, and optimum amount of the biogenic Mn oxides was found to 2 g/l. The maximum amount removal is on pH=6.5. The equilibrium data fitted well with the Langmiur isotherm equation, the maximal adsorption capacity were 115.6 mg/g.The biogenic Mn oxides is attached on the surface of microorganisms, its carbonization product is named as active carbon doped with Mn oxides. In this study, biogenic manganese oxides was impregnated with NaOH, then heated to prepare active carbon doped with Mn oxides and the optimal condition was 350℃ activation temperature,3 h activation time, agent ratio of 1:4 and in present of O2. The active carbon doped with Mn oxides contained 44.22% Mn, the ratio of Mn and O is 1:1.899 by XPS analysis. It was plate shaped, the specific surface area and pore diameter was 130.942 m2/g and 1.72 nm, respectively., The XRD analysis indicates it is s-MnO2. The increase of initial concentration of IC and temperature can increase the removal amount of IC. And the change of Mn ion concentration proves the existence of oxidation degradation. The analysis of the reaction products of IC showed that the degradation efficiency of IC is higher than commercial MnO2 and commercial activated carbon.These research provides a new thought and method to remove dyes pollution, and a new way to recycling utilization of Microbial remediation products from Mn pollution.