posted on 2021-04-29, 16:36authored byWenjing Xie, Peng Zhang, Wenjuan Liao, Man Tong, Songhu Yuan
The potential of oxygenating Fe(II)-bearing
sediments for hydroxyl
radical (·OH) production and contaminant degradation
has been proposed recently. Here, we further show that specific ligands
can largely enhance contaminant degradation during sediment oxygenation
due to increased utilization efficiency of sediment electrons. With
the addition of 0–2 mM sodium ethylene diamine tetraacetate
(EDTA) or sodium tripolyphosphate (TPP) in sediment suspension (50
g/L, pH 7.0), trichloroethylene (TCE, 15 μM) degradation increased
from 13% without ligand to a maximum of 80% with 2 mM TPP and was
much higher with TPP than EDTA because EDTA competes for ·OH. Electron utilization efficiency for ·OH production
increased with increased ligand concentration and was enhanced by
up to 6–7 times with 2 mM EDTA or TPP. Electron transfer from
sediment to dissolved Fe(III)-ligand is mainly accountable for the
enhanced electron utilization efficiency by the ligands with low adsorption
affinity (i.e., EDTA), and additional variation of sediment surface
Fe(II) coordination is mainly responsible for the enhancement by the
ligands with high adsorption affinity (i.e., TPP). Output of this
study provides guidance and optional strategies for enhancing contaminant
degradation during sediment oxygenation.