Study on removal effect of Cr(VI) and surface reaction mechanisms by bimetallic system in aqueous solution.

Fe/Al bimetallic particles were synthesized by chemical deposition. The materials were characterized by XRD and SEM. The structures of material with lower iron loading are solid ball like with a small amount of zero-valent iron. The structures of material with higher iron loading are porous ball like whose outer surface is almost entirely coated with zero-valent iron and provides more active sites. Different parameters affecting Cr(VI) removal rates were listed as research targets. The results showed that the removal rates can reach more than 90% under optimum conditions. In addition, Cr(VI) removal experiment was in accordance with the pseudo-first-order kinetics. SEM, FT-IR and XPS analysis were characterized after the reaction and the results proved that galvanic cell effect, the properties of reducibility of zero-valent metals, Fe(III)-Cr(III) mix phase hydroxides were the main surface reaction mechanisms for the reaction of Fe/Al bimetal with Cr(VI).