US EPA

1577882 

Journal Article 

Interaction of Cr 3+ with Silica Gel at the Aqueous Interface Using Fluorescence in Sodium Dodecyl Sulfate Micelles and Confocal Fluorescence Microscopy 

Idrees, M; Silva, M; Silva, AF; Zimmermann, LM; Bruch, J; Mendonça, CO; Almerindo, GI; Nome, RA; Atvars, TDZ; Fiedler, HD; Nome, F 

2012 

Yes 

Journal of Physical Chemistry C
ISSN: 1932-7447
EISSN: 1932-7455 

116 

5 

3517-3523 

English 

10.1021/jp2089164 

WOS:000299985300040 

http://pubs.acs.org/doi/abs/10.1021/jp2089164
Exit
 

Chemical composition and species distribution in clay
surfaces are key factors which control sorption and desorption processes of Cr3+ between sediment
and water. Adsorption of Cr3+ on silica gel has been studied by following the quenching of
naphthalene fluorescence in aqueous sodium dodecyl sulfate (SDS) micelles, which concentrate
naphthalene and Cr3+ in the micellar surface. Adsorption for pH <= 5 follows a Langmuir model,
and experimental data fitting is successfully described by a model based on discrete sites on the
surface with variable charge as a function of pH. Probably the mechanism of Cr3+ adsorption at
the silica gel surface is predominantly electrostatic, with outer-sphere complexation and ion
exchange with adsorbed H+ ions. Confocal laser-scanning fluorescence microscopy measurements
reveal the Cr3+ spatial distribution in three dimensions. Specifically, both images and spectra
measured with confocal microscopy indicate that Cr3+ is distributed across the entire particle,
not just adsorption at the surface.