Removal Of Carbofuran Phenol By Biogenic Manganese Oxides

With the rapid development of modern industry and agriculture,the pollution of carbofuran phenol has been more and more concerned with the use of broad-spectrum pesticide carbofuran and its substitutes.Biogenic manganese oxides with high valent manganese are insoluble and produced by the oxidation of low valent manganese with microorganisms.In this study,a manganese-oxidizing strain was ioslated from sludge of a manganese mine,and the removal of carbofuran phenol was studied in the presence of the biogenic manganese oxides,the manganese-oxidizing bacteria,and the biogenic manganese oxides and hydrogen peroxide,respectively.The carbofuran phenol removal process in real soil environment is simulated in the presence of the manganese-oxidizing bacteria.The result suggests that the biogenic manganese oxides has certain application prospect in the removal of carbofuran phenol.The main research results are as follows:1. The manganese-oxidizing strain Y-23 belongs to the genus of Bacillus,which was isolated from sludge of a manganese mine.The Mn???tolerance of the strain Y-23 was 150 mmol/L.The strain is non-motile,can grow at 15-40 ^oC and at p H 5.0-9.0,and resistant to ampicillin.The removal rate of Mn???was 44.7%and oxidation rate was 23.2%with the strain Y-23 under appropriate conditions.The content of high valent manganese produced by strain Y-23 was 4.16%.2. The crystallinity of biogenic manganese oxides produced by strain Y-23belongs to the amorphous structure.Its pore size distribution was 2 nm to 10 nm,the average pore size was 6.03 nm,and the specific surface area was 7.58 m²/g.3. In the co-culture experiment of manganese oxidizing bacteria and carbofuranphenol,the removal rate of carbofuran phenol was 30%at 10 d,and the introduction of Mn???in the the process could significantly improve the removal efficiency of carbofuran phenol to 60%.The removal efficiency?31.9%?of the Mn???-induced extracellular part was higher than that of the control group.SDS-PAGE results showed that two new protein bands were produced outside the cell after Mn???was introduced.These results showed that the extracellular proteins produced by the strain Y-23 after the inducetion of Mn???significantly improved its ability to remove carbofuran phenol.4. The presence of hydrogen peroxide significantly enhanced the removal of carbofuran phenol by biogenic manganese oxides.50 mg/L carbofuran phenol could be completely removed by 0.4 g/L biogenic manganese oxides and 100 mmol/L hydrogen peroxide.Compared with no hydrogen peroxide,the removal capacity was increased by 86%.In this system,the removal rate of carbofuran phenol was closely related to the initial concentration of biogenic manganese oxide,H₂O₂and carbofuran phenol,but not to the initial p H?5.0-9.0?.The removal process was fitted for first-order kinetic model and accompanied by the precipitation of Mn???and the decrease of p H.According to the experiments of free radical capture and GC-MS,the degradation mechanism of carbofuran phenol was proposed.5. In the simulated soil contaminated with carbofuran phenol,the residual of carbofuran phenol was 4.82%in the treatment added strain Y-23 at 2 d,which was significantly lower than that in the control?11.24%?and dead bacteria treatment?20%??p<0.05?.The effect of strain Y-23 on the removal of carbofuran phenol in manganese-containing soil was proved.