Column experiments and mathematical modeling results demonstrated that rhamnolipid biosurfactant can enhance the stability and mobility of iron oxide nanoparticles in water-saturated quartz sand.
Iron oxide nanoparticles were stabilized in water using the biosurfactant rhamnolipid, and the adsorption of U(vi) to these nanoparticles was measured and modeled as a function of water chemistry.
The application of positively
charged polymers is a common treatment
strategy for the sorption and separation of dissolved hexavalent chromium
Cr(VI). In particular, polyethylenimine (PEI) has been demonstrated
as an effective polymer for Cr treatment due to abundant amine groups
and cost-effectiveness. However, PEI as a photoactive polymer has
not been previously explored for Cr treatment. Toward this, we demonstrate
the significant photoactive potential of PEI for Cr sorption and reduction
[to Cr (III)], delineating amine structure–function relationships.
Overall, Cr(VI) photoreduction is enhanced dramatically as a function
of amine group density. Additionally, among the types of amine groups
evaluated, tertiary amines are observed to be the most reactive followed
by secondary and primary amines. When PEI is incorporated onto graphene
oxide (GO) as a stabilizing scaffold, mass loading of PEI is a key
variable for Cr(VI) treatment performance, which is observed to be
a function of PEI molecular weight and oxidation extent of GO. Finally,
when combined with magnetic nanomaterials, low energy, high efficiency
separation, and reuse are demonstrated. For these, sorption-based
separation processes maintained excellent performance over five cycles.
Taken together, this work demonstrates that PEI can serve as highly
effective, multifunctional material coating(s) not only for chromium
treatment but potentially for other oxidized aqueous species as well.
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