Imogolite-type nanoparticles in the environment: characterization, adsorption properties and biogeochemical significance

Imogolite-type nanoparticles, consisting of imogolite, allophane and their precursors, are important vectors for the cycling of phosphate, arsenate and other oxyanions, at least in forest soils and probably also in other environments. However, we know little about them compared to other important natural nanoparticles e.g.

Fe oxides.

Our main purpose is to increase the knowledge on the surface chemistry, ion adsorption properties, and biogeochemical significance of ITN.

First we will investigate the composition, size and morphology of ITN in twelve selected soil samples using a range of state-of-the-art methods, e.g. TEM-EDX, FTIR, SAXS, spTOF-ICP-MS, A4F, and XRD. Based on the results, a method for synthesis of ITN for adsorption studies will be optimised.

The surface charge and ion adsorption properties of ITN will be determined, to allow the development of a CD-MUSIC surface complexation model able to predict oxyanion adsorption in the environment.

Further, we will investigate to what extent ITN and ferrihydrite are intergrown through Al/Fe substitutions during their formation, and how this phenomenon may affect ion sorption. The extent to which three different organic acids are able to solubilize PO4 from ITN will be investigated. Finally, the improved model descriptions will be tested and evaluated for soil samples.

The knowledge gained in this project can be used to improve e.g. risk assessment of contaminated areas and fertilization strategies for soils.