Fenton-like Degradation Of Pollutants And Disinfection With Micro-Nano Structured Iron And Iron Based Composites

With the rapid development of industrial society, people’s living standards are improving unceasingly, which leads to serious environmental issues. As a result of the overexploitation and irrational utilization of natural resource, the ecological environment has been seriously polluted and destroyed, which will threaten human health and the sustainable development of society. Water is not only indispensable for people’s survival and development, but also has an influence on the development of economy. Recent years, with the rapid growth of the population and the development of economy, the discharge of domestic sewage and industry wastewater have resulted in the pollution of freshwater. The huge challenge we faced is that how to improve the efficiency of wastewater purification.From last century, scientists have focused on the polluted water purification and developed many wastewater treatment methods. Advanced oxidation processes have been receiving more and more attentions because it can produce reactive oxygen species to oxidize kinds of organic pollutants.In this paper, micro-nano structured Fe2O3@FeB composites were synthesized through reducing Fe2O3 by NaBH4 at ambient temperature and pressure. Through a series of characterizations, like XRD, SEM, TEM, XPS and Mossbauer spectra, we found that nanoscale flake structured amorphous FeB alloys were formed on the surface of Fe2O3 after being treated with NaBH4. We estimated the Fenton-like efficiency of the as-prepared samples with different NaBH4 treatment time for degradation of RhB under acidic and aerobic conditions, the results show that RhB degradation rate dependents on the content of low valent iron (FeⅡ and Fe0) and pure boron on the surface of Fe2O3@FeB composites. The contents of FeⅡ and Fe0 on the surface increased with the increasing of NaBH4 treatment time, leading to the promotion of Fenton-like reaction activity. Pure boron shows strong reducibility, and could reduce FeⅢ to FeⅡ. But the pure boron on the surface would be oxided to oxidized boron species, which is disadvantage to the FeⅢ/FeⅡ cycles. On the base of the characterization results, we put forward the Fenton-like mechanism of micro/nano structured Fe2O3@FeB composites under acidic condition: FeⅡ and Fe0 on the surface of Fe2O3@FeB composites could react with O2 to form H2O2 and ·O2 under acidic condition,·O2- can react with H+ to form H2O2 and follow the formation of H2O2, which could react with FeⅡ to form ·OH for degradation of pollutants. FeⅢ formed in the process could be reduced to FeⅡ by pure boron, leading to the regeneration of Fe.In addition, we prepared the Fe@Fe2O3 core-shell nanowires and investigated the inactivation of Escherichia coli (E. coli) in two different systems (Fe@Fe2O3/TPP system and Fe@Fe2O3 system). The results show that the inactivation efficiency of Fe@Fe2O3/TPP system towards E. coli is much higher than Fe@Fe2O3 system. The results of active species trapping experiments show that the addition of H2O2 scavenger could inhibit the inactivation of Escherichia coli. Then H2O2 was taken into account in these two systems and we found Fe@Fe2O3/TPP system could produce more H2O2 than Fe@Fe2O3 system, H2O2 might play a major role on inactivation of E. coli during the process.