Interaction of Surface Modified Silica Nanoparticles with Clay Minerals

C.O. Metin, Q.P. Nguyen
The University of Texas at Austin, US

Keywords: surface modified silica nanoparticles, adsorption, clay, montmorillonite, formation damage, clay swelling, polyethylene glycol, sulfonate, quaternary ammonium

Summary:

The interaction of silica nanoparticles with montmorillonite clay was investigated by visual swelling tests, Fourier Transform Infrared (FTIR), and x-ray diffraction (XRD). The adsorption of silica nanoparticles onto montmorillonite was also studied with a UV-Vis spectrophotometer. Silica nanoparticles with four different surfaces (unmodified, surface modified with anionic (sulfonate), cationic (quaternary ammonium (quat)) or nonionic (polyethylene glycol (PEG)) surfactant) were used. The adsorption of unmodified and sulfonate modified nanoparticles on clay was found to be insignificant. However, PEG and quat/PEG modified nanoparticles adsorbed significantly on montmorillonite. Adsorption isotherms were calculated for those nanoparticles.It is concluded that unmodified or sulfonate modified silica nanoparticles do not have any effect on clay swelling. However, PEG modified or quat/PEG modified silica nanoparticles decrease the extent of clay swelling. The presence of potassium ion improves the effectiveness of the inhibition of clay swelling by these nanoparticles. This study brings new insight into the understanding and modeling of the adsorption of surface modified silica nanoparticles onto clay minerals.