Magnetic vs. non-magnetic colloids - A comparative adsorption study to quantify the effect of dye-induced aggregation on the binding affinity of an organic dye.
J Colloid Interface Sci
; 481: 20-7, 2016 Nov 01.
Article
em En
| MEDLINE
| ID: mdl-27450888
ABSTRACT
HYPOTHESIS:
Due to attractive magnetic forces, magnetic particles (MPs) can exhibit colloidal instability upon molecular adsorption. Thus, by comparing the dye adsorption isotherms of MPs and non-magnetic particles of the same size, shape and functional group it should be possible to characterize the influence of magnetic attraction on MP aggregation. EXPERIMENTS For a range of particle densities, a comparative adsorption study of malachite green (MG(+)) onto magnetic and non-magnetic colloids was carried out using a combination of a separation technique coupled with UV-vis spectroscopy, optical microscopy, and polarization dependent second harmonic generation (SHG) spectroscopy.FINDINGS:
Significant MP aggregation occurs in aqueous solution due to MG(+) adsorption. This alters the adsorption isotherm and challenges the determination of the adsorption equilibrium constant, Kads. The dye-induced aggregation is directly related to the MG(+) concentration, [MG(+)]. A modified Langmuir equation, which incorporates loss of surface sites due to this aggregation, accurately describes the resulting adsorption isotherms. The Kads of 1.1 (±0.3)×10(7) and a loss of maximum MP surface capacity of 2.8 (±0.7)×10(3)M(-1) per [MG(+)] has been obtained. Additionally, SHG has been established as an effective tool to detect aggregation in nanoparticles.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
J Colloid Interface Sci
Ano de publicação:
2016
Tipo de documento:
Article