Synthesis and characterization of manganese-iron oxide composites for adsorption of transition metal ions

Abstract

The composites of iron oxide and managanese oxide are synthesized using various approaches, in order to improve the heavy metal capacities and filtration quality of iron oxide. The exfoliation-precipitation approach is successful to produce the composites with highly distribution of Fe and Mn over the composites as observed by SEM-EDX, and high BET specific surface area. This approach utilizes two steps (1) the exfoliation of preformed birnessite (layered managanese oxide) using tetrabutylammonium hydroxide solution, and consequently (2) the precipitation with Fe-polycation in basic solution. The composites are comprised of the nanocyrstallites of birnessite and goethite, indicating by XRD and FT-ir. The adsorption capacities towards copper and lead ions are much (10-35%) higher than the physical mixtures of pure goethite and birnessite. The filtration qualities of all composites are also improved, comparing to that of pure goethite. The clear filtrate is found using the composite with 80 wt% Fe to total metal as an adsorbent.