Asphaltene Adsorption onto an Iron Surface: Combined Near-Infrared (NIR), Raman, and AFM Study of the Kinetics, Thermodynamics, and Layer Structure

Abstract

A combination of near-infrared (NIR) spectroscopy, Raman microscopy, and atomic force microscopy (AFM) was used to analyze the adsorption behavior of petroleum macromolecules (asphaltenes) on an iron (Fe) surface. A partial least-squares (PLS/PLSR) regression method was used for determining the concentration from NIR spectroscopic data. A Langmuir model was used to fit the experimental data. Effective kinetic and thermodynamic parameters (Gibbs energy of adsorption, adsorption/desorption rate constant, maximal adsorbed mass density) of asphaltenes adsorbed from benzene solution were evaluated: the maximum adsorbed mass density (Γ max ) was found to be 4.90 ( 0.07 mg m -2 ; the adsorption constant (K) was found to be 0.084 ( 0.007 L mg -1 ; and a value of 34.3 ( 0.2 kJ mol -1 was calculated for the effective Gibbs energy of absorption (-ΔG ads ). The structure of the adsorbed layer was also analyzed by AFM. Asphaltenes were found to form aggregates on Fe surface with an average size of a few hundred nanometers. The notion of a nonuniform distribution of crude oil macromolecules adsorbed on metal surfaces was experimentally confirmed.

Asphaltene fractionation based on adsorption onto calcium carbonate: Part 1. Characterization of sub-fractions and QCM-D measurements

“…[39] Asphaltene adsorption of upto 5 mg/m 2 has been observed on iron oxide surface. [46] However, multilayer adsorption of asphaltenes onto mineral surfaces (Bedford limestone, Berea sandstone and dolomite) with adsorbed values in the range 100 -200 mg/m 2 at very high asphaltene concentrations in toluene has also been reported. [47] The multilayer step wise asphaltene adsorption has been attributed to the asphaltene association and formation of aggregates.…”

Determining the Kinetics of Asphaltene Adsorption from Toluene: A New Reaction–Diffusion Model

“…Although generally stable in liquid crude oil under the conditions present 25 in the reservoir, changes in pressure, temperature, composition and shear rate may result in the 26 precipitation and subsequent deposition of asphaltene. Deposited asphaltene can build up at many 27 places along the oil production system, for example, inside wellbores, pumps, tubing, wellheads, safety 28 valves, flowlines and surface facilities [1]. These deposits reduce the efficiency of oil production and in 29 extreme cases they can completely plug the wellbore.…”

Genetic Algorithm Development for Prediction of Modified Langmuir Isotherm Parameters of Asphaltene Adsorption onto Metal Surfaces: Using Novel Quartz Crystal Nanobalance

“…A Langmuir model fitted the experimental data. [32] Marczewski and Szymula studied adsorption of asphaltenes on soils arguing it to be one of the important problems, though largely under estimated, in environment protection of Lublin region. The adsorption study for different kinds of soil involved using spectroscopy technique wherein the asphaltene content of solution before and after adsorption was measured.…”