Incorporation of nanoscale zero-valent iron particles in monodisperse mesoporous silica nanospheres: Characterization, reactivity, transport in porous media

In this study, nanoscale zerovalent iron (nZVI) was incorporated inside the channels of monodisperse mesoporous silica nanospheres (MSN). The techniques of TEM, XRD, FTIR, N-2 adsorption-desorption and XPS were conducted to characterize the composition and structure of the composite materials. Results revealed that nZVI was well dispersed in the channels of MSN, and the synthesized Fe/Si composite materials (nZVI@MSN) remained monodisperse nanospheres with the size of 100 nm which was in the optimal size range for transport through porous media. The loading of Fe (wt %) in nZVI@MSN was 4.3% and the BET surface area of nZVI@MSN was 743.49 m(2)/g. Batch experiment results revealed that the removal efficiency of nitrobenzene (NB) by nZVI@MSN was 42.9% higher than that of bare nZVI. Lower initial solution pH could favour the removal of NB. Most of the common ions including Na+, K+, Cl-, NO3- and SO42- presented no obvious effect on NB removal. While, Ca2+, Mg2+ and HCO3- showed promoted inhibitory effect on NB degradation with the increased of ion concentration. After seven cycles of reduction, the removal efficiency of NB by nZVI@MSN was higher than 86%, indicating its high stability and durability. Transport experiments showed that nZVI@MSN performed better mobility in porous aquifer media than bare nZVI.