Enhanced Arsenite Adsorption onto Litchi-Like Al-Doped Iron Oxides

Iron-aluminum complex hydroxide/oxides were synthesized from a hydrothermal process, and litchi-like Al-doped iron oxide nanoparticles were then obtained by removing extra boehmite nanoplates with NaOH washing. While the hydrothermal synthesis induced doping of iron oxide by Al, with the Al dopant concentration increasing with the Al-Fe molar ratio, removal of boehmite greatly increased the specific surface area (SSA) of these Al-doped iron oxide nanoparticles. The resulting litchi-like Al-doped iron oxide nanoparticles were found to strongly adsorb As(III) from aqueous environment at neutral pH without preoxidation., and the As(III) (arsenite) adsorption capacity of Al-doped iron oxides increased with the increase of the initial ratio of Al/Fe in the hydrothermal process, reaching as high as 2.5 times the adsorption capacity of pure iron oxide. The enhanced arsenite adsorption was shown to result from the increases in the amount of the surface hydroxyl group as well as in the SSA of Al-doped iron oxide nanoparticles.