Synergistic adsorption of As(V) from aqueous solution onto mesoporous silica decorated orderly with Al2O3 and Fe2O3 nanoparticles.

An improved incipient wetness process was developed to decorate mesoporous silica, in which Al was preloaded onto mesoporous SBA15 followed by decoration of Fe2O3 nanoparticles. This decoration process exploited the homogeneous dispersivity of Al in silica framework and overcome the problem of aggregation of Fe2O3 nanoparticles, which in turn resulted in a synergistic adsorption of As(V) much higher than that of either metal oxide alone. It was found that the prepared adsorbent had mesoporous structure, large specific surface area, and high pore volume according to TEM, N2 adsorption-desorption isotherms, and XRD analysis. Adsorption kinetics was elucidated by pseudo-second-order kinetic equation and abided by a three-stage intraparticle diffusion mode. Langmuir and Freundlich models were applied to fit the adsorption isotherm. It was proved that Fe@Al-SBA15 is a more efficient and effective adsorbent for As(V) than single metal oxide impregnated mesoporous materials, yet it maintains a desirable life cycle.