Preparation Of The Chemical And Biogenic Fe-Mn Binary Oxide And Their’s Adsorption And Oxidation Characteristics Of Co(Ⅱ)

With the rapid development of economy and industry,the pollution caused by heavy metal has increased prominently and become one of the most threatening environment issues.So looking for the effective treatment method of metal contaminated environment has become an urgent matter.Cobalt is an important mineral resource and plays an irreplaceable role in industrial,medical and military.So the pollution caused by cobalt is relatively common.The wide existence of Iron and Manganese oxides in the environment,has important effect on morphology,transformation and biotoxicity of heavy metal.Thus,the research on the adsorb ability of iron and manganese oxides for heavy metal has practical significance.So far,the adsorb ability for heavy metals of the oxides has been conducted a lot,but iron and manganese oxides usually coexist in soil and water and form mixed state of iron and manganese oxides,which has not been researched systematically.And the mixed state of iron and manganese oxides formed by microorganism has not been reported yet.In this paper,adsorption and oxidation characteristics of Fe-Mn binary oxides for Co(II)was studied.The Fe-Mn binary oxides formed by chemical synthesis were characterized by BET,XRD,SEM,XPS,FTIR,ZATA.Then,the effects of temperature,pH,dosage,iron strength on Co removal were studied.Moreover,the characterization of FTIR and XPS of the oxides before and after adsorption gave information about the changes of its surface structure.At the same time,four Fe-Mn binary oxide formed by Fe-Mn oxidizing bacteria under different conditions were characterized by SEM-EDX and FTIR,XPS of the these oxides after adsorbed Co(II),which provided scientific evidence for the in-depth understanding of the environmental behavior of iron and manganese oxides.The major research results are as follows:The studies showed that the surface area of Fe-Mn binary oxide was 316.8m2/g,which was higher than that of hydrated manganese dioxide(266.9m2/g)and ferrihydrite(172.3 m2/g).The Fe-Mn birany oxide has high BET,small medium mass particle size and the ZPC was 6.02.At the same time,the SEM showed that the particles were string or spherical and sticked to each other,formed a net structure.The XRD and XPS pattern of Fe-Mn binary showed that the main component was FeMnO3,and it also contained small amount of iron and manganese oxides,such as δ-MnO2 and Fe2O3.The FTIR spectra found MnO2 unit cell in Fe-Mn binary oxide and observed the characteristic absorption peak of δ-MnO2,Fe2O3 and surface hydroxyl groups.Then,the impact factors pH,temperature,adsorbent dose and ionic strength were investigated.The results showed that it has the best depletion of Co(Ⅱ)at pH 6-8,and the removal ability increased with the temperature changed form 20℃ to 40℃,and when the ironic strength was 0.01mmol/L,the removal ability better than that in other ironic strength.The removal ability of Fe-Mn binary oxide increased with the increasing of adsorbent dose,but the adsorption quantity decreased,and the adsorption quantity was 29.6 mg/g when dosage was 0.05g/L.The FTIR spectra of the Fe-Mn binary oxide before and after Co(Ⅱ)adsorption showed that surface hydroxyl,Mn-OH and FeOH existed in the surface and there formed Mn-O-Co or Fe-O-Co.The investigation also found that iron oxide mainly showed adsorption ability,while the manganese oxide also showed adsorption and oxidation ability.The XPS spectra confirmed that the Mn of Fe-Mn binary oxides and hydrated manganese dioxide were reduction while Fe of Fe-Mn binary oxide and ferrihydrite had no difference after reaction with Co(Ⅱ).Four biogenic Fe-Mn binary oxides were formed by the isolated Mn oxiding bacterium H1 in different condition.The Fe utilization ability of Mn oxiding bacteria were investigated when Fe supplied in different forrms,and then their difference in removal ability of Co(Ⅱ)was studied.The results showed that the Co(Ⅱ)removal ability of the four biogenic Fe-Mn binary oxides and the biogenic manganese oxide as follows:biogenic Fe-Mn binary oxide A>biogenic Fe-Mn binary oxide C>biogenic Fe-Mn binary oxide D>biogenic Fe-Mn binary oxide B>biogenic manganese oxide.The FTIR and XPS spectra analysis found that the removal mechanism of Co(Ⅱ)by biogenic Fe-Mn binary oxide was the same as chemical Fe-Mn binary oxide.Mn-OH and Fe-OH existed in the surface and there formed Mn-O-Co or Fe-O-Co.the valance of Mn was changed.Iron oxide mainly showed adsorption ability,while the manganese oxide showed adsorption and oxidation ability.