Formation Of Biogenic Manganese Oxide And Oxidative Degradation Of Environmental Representative Enstrogens

It is very popular that environmental estrogens distribute in environment, which is hazardous for humans and animals health. Hence, there is growing concern about the environmental behavior and degradation behavior of environmental estrogens. Biogenic manganese oxides can adsorb and degrade organic compounds or heavy metals. So, it can be used as a new cost-effective technology for water treated by biogenic manganese oxide.In our research, the mixture of manganese oxidizing bacteria was enriched from paddy soil collected from Jinhua. The collected biogenic manganese oxides formed by isolated manganese oxidizing bacteria was used as an oxidant for the oxidative degradation of estradiol (E2) and ethynylestrdiol (EE2). The adsorption of estrogen degradation by mixed bacteria was not very obvious, and the adsorption efficiencies of E2 and EE2 were about 2.4% and 10%, respectively. It was also found that 70% of E2 and 52% of EE2 could be degraded by biogenic manganese oxides, respectively. While compared with the chemical manganese oxides, more E2 and less EE2 were degraded by biogenic manganese oxides. The degradation efficiency was compared in two different systems including solution of biogenic manganese oxides and the mixture solution of Mn oxidizing bacteria with Mn2+, and the similar degradation trend of estrogen degradation was found in two systems, while the degradation efficiency in the former was much higher than that in the latter because more amount biogenic manganese oxides were existed firstly in the former solution. Furthermore, the degradation efficiency was evaluated when some factors such as pH and biogenic manganese oxides loading changed. It was favored for E2 and EE2 degradation when in acid condition and more biogenic manganese oxides added in neutral condition.By analyzing the MS spectrum, it was found that estrone (E1) was the main intermediate during E2 and EE2 degraded by biogenic manganese oxides. And then, E1 was oxidized to low molecular matter. The estrogenic activity was determined by yeast estrogen screen. The data showed that estrogenic activity was decreased significantly by biogenic manganese oxides. It could be concluded that biogenic manganese oxides not only decrease the concentration of estrogen, but also decrease the estrogenic activity.SEM, TEM-EDX, XRD, and XPS were used to characterize the biogenic manganese oxides. There was a little amount of biogenic manganese oxides on the bacterial surface, and the morphology liked Mn2O3 and MnO2. The newly formed biogenic manganese oxides had nano-scale. After 2 to 4 weeks, the biogenic manganese oxides were mineralized to high crystallinity.This study may provide useful information to better understanding the fundamental knowledge relevant to the interaction of organic pollutants and manganese oxides in natural environment.