Electrostatic adsorption of hematite nanoparticles on self-assembled monolayer surfaces
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Deposition of nanoparticles (NPs) on different environmental surfaces has important implication on their fate and transport in aquatic systems. This study quantitatively and kinetically analyzed the adsorption of hematite (α-Fe2O3) NPs (HNPs) onto self-assembled monolayer modified surfaces using QCM, AFM, and SEM. Experiments were conducted to study the immobilization of two different sizes of HNPs onto gold substrate and surfaces modified with 1-mercapto-11-undecanoic acid and cysteine. It is shown that the extent and rate of HNPs adsorption onto substrate surfaces can be modulated electrostatically. Control over the surface coverage of the adsorbed HNPs has been demonstrated by pH variation. Size-dependent adsorption kinetics was observed, with the 79 nm HNPs adsorbed 2–3 times faster than the 116 nm HNPs.
KeywordsSolid-water interface Quartz crystal microgravimetry (QCM) Atomic force microscopy (AFM) Scanning electron microscopy (SEM)
Atomic force microscopy
Dynamic light scattering
Natural organic matter
Quartz crystal microgravimetry
Scanning electron microscopy
Transmission electron microscopy
We are grateful to Benny Freeman for the opportunity and access to the SurPASS electrokinetic analyzer. Andrew S. Madden is grateful for laboratory assistance from Matthew Miller, Andrew Swindle, and Virginia Grace. This research was partially supported by NASA award NNX11AH11G to Andrew S. Madden.
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