Effects of Resin I on Asphaltene Adsorption onto Nanoparticles: A Novel Method for Obtaining Asphaltenes/Resin Isotherms

The main objective of this study is to investigate the effect of resin I on the adsorption behavior of n-C-7 asphaltenes onto silica and hematite nanoparticles. It is worthwhile to mention, for the first time, that competitive adsorption of n-C-7 asphaltene and resin I over nanoparticles is reported. Indeed, a novel method based on thermogravimetric analysis (TGA) and softening point (SP) measurements was used for the simultaneously construction of adsorption isotherms of n-C-7 asphaltenes and resins. The adsorption experiments were conducted in the batch mode at different n-C-7 asphaltene to resin I (A:R) ratios of 7:3, 1:1, and 3:7 and different concentrations of the asphaltene-resin mixture from 500 mg/L to 5000 mg/L. The adsorption isotherms were described by the solidliquid equilibrium (SLE) model. The results showed different shapes of the adsorption isotherms according to the A:R ratio. However, the nanoparticles become more selective for asphaltene at a high asphaltene/resin ratio. In addition, the amount of n-C-7 asphaltenes adsorbed at any of the A:R ratios evaluated was successfully predicted from a known amount adsorbed at a determined A:R ratio, following a simple rule of three. Results indicated that resin I does not have significant influence on the adsorbed amount of asphaltenes, showing that resin I has a solvent-like behavior, such as toluene, mainly at low concentrations (<3000 mg/L).