Project

High affinity adsorption to Fe-oxide nano particles. Does it occur and is sulfate involved?

Sulfate is an anion omnipresent in natural systems, where it is bound by metal (hydr)oxides. Ferrihydrite is the most reactive nano-Fe-oxide material in nature. Therefore, its ion adsorption properties are crucial for understanding the chemical behaviour of soils. Ferrihydrite is chemically heterogeneous and may have a range of reactive sites with a different affinity (logK) for the binding cations.

Background

For anions, chemical heterogeneity of ferrihydrite has not been considered, but this is presently questioned. This study aims to contribute to an improved understanding of the adsorption of oxyanions to ferrihydrite in general, using SO4 as a proxy because this anion typically covers the range of surface loadings where oxyanions are sensitive to sites that differ in chemical affinity. The challenge is to collect new SO4 adsorption data using ferrihydrite material that is well-characterized and this may serve as a reference to also include literature data. Collectively, this can be interpreted with state-of-the-art surface complexation modelling to reveal the chemical heterogeneity (logK) of sites that bind oxyanions.

Used skills

  • Experimental work using lab-synthesised and well-defined ferrihydrite;
  • Depending on the interest of the student, surface complexation modelling can also be part of the work.

Requirements

  • Knowledge of ion adsorption and reactive materials as treated in Chemical Processes in Soil, Water and Atmosphere (SOC22306);
    • Introduction in surface complexation modelling as given in the MSc course Applications in Soil and Water Chemistry (SOC34806) can be helpful;
    • Environmental Analytical Techniques (SOC-33806) can be helpful.

Supervisor