Effect of aluminum modified mesoporous SBA-15 on surface properties and arsenic adsorption performance

Aluminum-modified SBA-15 mesoporous materials (Al-x-SBA-15) were synthesized and used as the efficient adsorbents for As(V) removal. The effects of aluminum loading on the physicochemical properties such as microstructure, aluminum coordination environment and surface acidity of Al-x-SBA-15 were investigated carefully, and their correlation with adsorption performance was also studied in depth. After aluminum impregnation, aluminum oxide compounds with different coordination environments (AlO3, AlO4, AlO5, and AlO6), which contributed effectively to the active adsorption centers for As(V) removal, were successfully introduced onto the Al-x-SBA-15 samples with the maintenance of the ordered mesoporous structure of SBA-15. However, a decrease in specific surface area and pore volume of the sample was also caused by the increase of aluminum introduction. Moreover, an excessive increase of the aluminum loading led to the overlapping arrangement of aluminum oxides on the surface of SBA-15, which resulted in the obvious decline of the terminal Al-OH functional groups and acid centers. When the loading of aluminum was 10%, the positive and negative factors reached a balance, and then the highest adsorption capacity of 95.7 mg/g(A1) for As(V) was obtained. The adsorption kinetics of As(V) on Al-x-SBA-15 conformed to the pseudo-second-order kinetic equation and the intraparticle diffusion model, and the adsorption rate was controlled by both film diffusion and intraparticle diffusion. In conclusion, Al-10-SBA-15 is an efficient As(V) adsorbent that can treat actual arsenic-contaminated wastewater with the arsenate of 1.998 mg/L (and 1.242 mg/L) to reach drinking water standards.

Automated summary

Aluminum-modified SBA-15 mesoporous materials were synthesized and used as efficient adsorbents for As(V) removal. The effects of aluminum loading on the physicochemical properties of Al-x-SBA-15 were investigated, and it was found that an optimal loading of 10% resulted in the highest adsorption capacity. The adsorption kinetics were found to be controlled by both film diffusion and intraparticle diffusion.