1 research outputs found
Polyphosphates and Fulvates Enhance Environmental Stability of PO<sub>4</sub>‑Bearing Colloidal Iron Oxyhydroxides
Iron
oxyhydroxide nanoparticles (Fe-NPs) are natural vectors of
phosphate (PO<sub>4</sub>) in the environment. Their mobility is determined
by colloidal stability, which is affected by surface composition.
This might be manipulated in engineered NPs for environmental or agricultural
applications. Here, the stability of PO<sub>4</sub>-Fe-NPs (HFO/goethite)
was determined across contrasting environmental conditions (pH, Ca
concentration) and by using fulvates (FA) and polyphosphates (poly-P’s)
as coatings. The PO<sub>4</sub>-Fe-NPs are unstable at Ca concentrations
above 0.1 mM. Addition of FA and some poly-P’s significantly
improved stability. Zeta potential explained colloidal stability across
treatments; surface charge was calculated with surface complexation
models and explained for phytic acid (PA) and hexametaphosphate (HMP)
by a partial (1–4 of the 6 PO<sub>4</sub> units) adsorption
to the surface, while the remaining PO<sub>4</sub> units stayed in
solution. This study suggests that Ca concentration mainly affects
the mobility of natural or engineered PO<sub>4</sub>-Fe-NPs and that
HMP is a promising agent for increasing colloidal stability