Size distribution of ferrihydrite aggregate and its implication for metal adsorption and transport

Haruka TSUBAKI, Takumi SAITO, Takashi MURAKAMI
2012 Journal of Mineralogical and Petrological Sciences  
Adsorption experiments of Zn onto ferrihydrite were carried out at different initial Fe concentrations and pH, and at room temperature. Zincadsorbed ferrihydrite was fractionated to examine Zn adsorption among differentsize aggregates of ferrihydrite. Primary ferrihydrite particles were as small as 5 -7 nm in diameter and they formed aggregates of <0.25 to >32 µm in size. The dominant size of the aggregates decreased with a decrease in the initial Fe concentrations and pH. Zinc was adsorbed on
more » ... nc was adsorbed on the surface of individual ferrihydrite nanoparticles but not on that of ferrihydrite aggregates, indicating that ferrihydrite nanoparticles were so loosely attached to one another in aggregates that individual nanoparticles could adsorb Zn. The size distribution of ferrihydrite aggregates and the Zn adsorption on individual ferrihydrite nanoparticles can change the sedimentation rate of ferrihydrite aggregates and the behavior of Zn during the transformation of ferrihydrite to goethite and hematite. Therefore, our results will give a deeper understanding of metal transport by ferrihydrite.
doi:10.2465/jmps.120618 fatcat:xq4xkuhmhbcijg7252fwvwlqw4