Adsorption of Naphthenic Acids onto Mineral Surfaces Studied by Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D)

Abstract

In the present research, the adsorption of naphthenic acids from n-dodecane solutions onto hydrophilic surfaces of the most common minerals in petroleum reservoirs (silica, alumina, and calcite) has been investigated using the quartz crystal microbalance with dissipation monitoring (QCM-D). The wettability and surface roughness of the mineral surfaces applied for the QCM-D measurements were determined with contact angle and atomic force microscopy (AFM) measurements. Corrections for changes in bulk density and viscosity of the naphthenic acids solutions as a function of concentration are necessary to determine the actual adsorption levels for the QCM-D measurements and have been accounted for in the adsorption calculations. The adsorption affinity of the naphthenic acids to the mineral surfaces is ranked as calcite > alumina > silica. The adsorption data for all systems can be adequately well described by the Langmuir isotherm and adsorption free energies (ΔG°) calculated from the fitted Langmuir isotherms indicate that the binding between naphthenic acids and mineral surfaces is of a physical nature. Plots of change in surface area per molecule (σ) as a function of the variation of concentration indicate that the adsorption process of the naphthenic acids changes as a function of surface coverage and suggest that the naphthenic acids chains undergo conformational alterations during the adsorption. The surface area per molecule (σ) of the adsorbed naphthenic acids onto the mineral surfaces is calcite < alumina < silica for all concentrations, which supports the adsorption affinity ranking.

Asphaltene Adsorption from Toluene onto Silica through Thin Water Layers

“…This conclusion is consistent with available literature. [24][25][26][27][28][29][30] Agreement with the Langmuir equilibrium model in Figure 7 is incompatible because of the observed irreversible attachment of toluene-solubilized asphaltene to the silica surface. However, slow rearrangement kinetics of initially reversible adsorbed configurations can lead to an early-time apparent Langmuir isotherm.…”

“…Our measured amounts are in general agreement with literature despite differences in asphaltene sources. [24][25][26][27][28][29] Asphaltene strongly adsorbs from toluene onto silica when not in the presence of water.…”

Interfacial and Colloidal Forces Governing Oil Droplet Displacement: Implications for Enhanced Oil Recovery

“…Compared to asphaltenes, naphthenic acids are of lower molecular weight, typically less than 450 g/mol, spanning mainly C 10 to C 50 compounds with up to six fused ring structures that are mostly saturated [35]. Naphthenic acids preferentially adsorb on carbonate solid surfaces mainly by chemical interactions to modify the wettability from water-wet to oil-wet as the surface becomes saturated, although the process is reversible at elevated temperatures [36,37].…”

Molecular simulations of NAPL removal from mineral surfaces using microemulsions and surfactants

“…Highly polar components such as carboxyli et al showed that naphthenic acids readily adsorb and are retained by calcite, even after a desorption sequence. 5 Molecular dynamics simulations (MD) revealed that alcohols can adsorb strongly to the calcite surface, effectively altering its wettability. 6 Gomari and Hamouda concluded that medium chain fatty acids are able to alter the wettability of calcite, even when a thin water film is present.…”