Study On Adsorption Of Pb(?) On The Biogenic Manganese Oxides And Activate Carbon Doped With Biogenic Manganese Oxides

In recent years,with the rapid development of industry,the pollution of heavy metal has become serious.The excessive manganese?Mn?and lead?Pb?can damage human health.The industrial waste water has become the main source of manganese and lead pollution.Therefore,it is concerned that how to remove the manganese and lead from waste water.The biogenic manganese oxides are formed by the microorganism oxidizing Mn???,which have large specific surface area,weak crystal type,many cation vacancy and large adsorption ability.Now it has become the hot spot of research that biogenic manganese oxides and activated carbon is used to remove heavy metal.The major works of this thesis are as follows;1.The manganese oxidizing bacteria 4-15 was isolated from manganses polluted soil of Guizhou.Its minimal inhibitory concentration of Mn???was 60 mmol/L.Its growth was restrained with the increase of Mn???concentration.At 10 mmol/L Mn???concentration,the removal rate of Mn???was 33.55% and the oxidation rate was 29.5%.2.The total Mn content of the biogenic manganese oxides produced by the strain4-15 at 10 mmol/L Mn???concentration was 33.42%.The biogenic manganese oxides was porous and the surface area was 73.35 m2/g.The Fourier Transform infrared spectroscopy?FTIR?results showed that it has functional groups containing oxygen.The XRD results showed that it belonged weak crystal type of manganese oxide.It would reach the adsorption equilibrium at 6 h at 25? when the initial Pb²⁺ concentration was500 mg/L and the adsorption fitted for pseudo-second-order kinetic model.The adsorption isotherm was fitted for the Langmuir isotherm and the maximum adsorption capacity was 1206 mg/g.The adsorption amount increased with pH increase and reduced with ionic strength increase.3.The activated carbon doped with manganese oxides was prepared by carbonizing the biogenic manganese oxides produced by Mn-oxidizing bacterial Marinobacter sp.MnI7-9 in a tube furnace under N2 at 300? for 2 h.The content of C and Mn were39.3% and 46.76% respectively.SEM results showed that the particles of activated carbondoped with manganese oxides have a layered structure with many pores.The FTIR results showed that its has functional groups containing oxygen.The XRD results showed that it belonged weak crystal type of manganese oxide.It would reach the adsorption equilibrium at 22 h at 25 ? and the initial Pb²⁺ concentration was 500 mg/Land the adsorption kinetics fitted for pseudo second-order kinetics.The adsorption isotherm data could be described by the Langmuir isotherm and the maximum adsorption capacity was1128 mg/g.The adsorption capacity increased with pH increase and the adsorption is weakly affected by ionic strength.After blocked the carboxyl and hydroxyl groups,the adsorption capacity was reduced 24.72% and 20.06%,which indicated the adsorption through forming surface complexation with Pb²⁺.In conclusion,this thesis isolated a strains 4-15 which has manganese oxidation ability,the biogenic manganese oxides produced by strain 4-15 and the activated carbon doped with manganese oxides prepared by carbonizing the biogenic manganese oxides produced by Marinobacter sp.MnI7-9 have a strong adsorption ability on Pb²⁺ which have a certain application prospect.