Removal Of Disinfection By-products Using Nano-iron Supported On Ordered Mesoporous Silica In Water Research

With the rapid development of economy and promote level of urbanization, pollution of surface water is increased year by year. At the same time, drinking water health standards improved, which making the conventional water treatment process can not meet the requirement of the water quality. So, advanced drinking water treatment technology emerged as the times required, Ozone oxidation process was one of them. Although the ozone oxidation effect was good, But it could produce the disinfection by-products such as bromate. Bromate has been classified as a group 2B or possible human carcinogen by the International Agency for Research on Cancer, and according to drinking water quality standards in China(GB5749-2006), the maximum contaminant level for bromate is 10μg/L. So the bromate removal research has become a hot topic in recent years. In this study, we make the nano zero-valent iron load to the surface of ordered mesoporous silica by liquid phase reduction method, which was to avoid nano zero-valent iron harden oxidation, and by nano zero-valent iron and mesoporous materials combined action for bromate removal research.The research mainly included the following three aspects:First, we make the nano zero-valent iron load to the surface of ordered mesoporous silica by liquid phase reduction method, and characterized the composite structure by X-ray diffraction(XRD) and scanning electron microscopy(SEM). The results show that nano zero-valent iron has been successfully loaded to the surface of the ordered mesoporous silica, and even distributed.Then, determined the optimal condition of nano zero-valent iron composite material for bromate removal, and analysised experiment factors specifically. The experimental results show that when the initial bromate concentration was 200μg/L, dosing quantity was 25 mg, pH=6.5, DO=0mg/L, the reaction time for 60 min were the best bromate removal conditions. And the removal efficiency of bromate by nano zero-valent iron composite material was decreased with the increasing of the bromate and DO concentration. Increased with the increasing of material dosing quantity. Acidity and alkalinity could affect the removal of bromate. Meanwhile, the inorganic anions in the water such as Nitrate, phosphate, nitrite, etc have different influenced in bromate removal.Thirdly, the mechanism of the study found that the nano zero-valent iron composite material in bromate removal corresponded Langmuir adsorption isotherm models and pseudo-second order kinetic model. Through the analysised of the product we found that during the first 30 min, adsorption played mainly role in the removal reaction, and then the reduction reaction rised rapidly, bromate adsorption capacity gradually decreased, and the reduction product was only bromide ions.