Simultaneous adsorption/reduction of bromate in water using nano zero-valent iron supported on ordered mesoporous silica

Bromate is mainly produced by ozone oxidation, and it is a kind of highly toxic substance in drinking water and a serious threat to people's health. It is difficult to remove it using traditional processes. The reduction of nano zero-valent iron (nZVI) has proved to be an effective method to remove bromate in water. In this study, we designed and prepared a new kind of nanocomposite by loading nZVI into ordered mesoporous silica materials (nZVI/MCM-41), which avoided nZVI oxide and increased adsorption at the same time. The removal efficiencies of bromate by MCM-41, nZVI, and nZVI/MCM-41 were evaluated respectively. The result indicated that nZVI/MCM-41 showed the highest removal efficiency for bromate at pH 6.5, with an appropriate dose of 25 mg when initial bromate concentration was 0.2 mg/L. In the removal process, adsorption and reduction exist at the same time and reduction was the leading role. Kinetic studies showed that the removal of bromate by nZVI/MCM-41 followed pseudo-first-order kinetics. Finally, bromine mass balance demonstrated that bromide was the only product for bromate reduction, suggesting that bromate was first adsorbed onto nZVI/MCM-41 and reduced to innocuous bromide by nZVI subsequently.