Asphaltene Aggregation in Aqueous Solution Using Different Water Models: A Classical Molecular Dynamics Study

Abstract

The aggregation behavior of asphaltene in aqueous solution is systematically investigated based on a classical molecular dynamics study. In this work, a novel approach is adopted in order to investigate the structural and dynamical properties of the asphaltene nanoaggregates using different water models. The end-to-end distance of the asphaltene molecule is probed in order to understand the aggregation behavior in aqueous solution. The accuracy of different water models, that is, simple point charge, TIP4P-D, and TIP5P, is thoroughly investigated. In order to probe the dynamical properties of the asphaltene nanoaggregates, the transport coefficients, namely, diffusion coefficient and shear viscosity, are computed. The obtained results highlight the importance of using the appropriate water model in order to accurately study the aggregation behavior of asphaltene in aqueous solution.

Combined experimental and molecular dynamics investigation of 1D rod-like asphaltene aggregation in toluene-hexane mixture

“…The extended chain length for asphaltene is found to be 24.5 Å. The aliphatic sidechains can change the persistence length in aqueous solution [40] and in organic solvents. The stiffer aliphatic side chains are found on shorter length scales and the longer length scale side chains bend to participate in the aggregation process.…”

“…The distance between one end of the aliphatic side chain to the other end is termed as the end-to-end distance. This distance is crucial in understanding the aggregation behaviour of asphaltenes in aqueous solution as established by one of our previous works [40]. In this study, we probed the end-to-end distance to understand the aggregation behavior of asphaltenes in hexane and toluene mixture considering the semi-flexible side chains [41] within the worm-like chain model [42].…”

“…The end-to-end distance of the asphaltene molecule averaged over all asphaltene molecules is evaluated over the entire MD production run using the following Eq. 2 [41,40]:…”

Role of Ionic Liquid in Asphaltene Dissolution: A Combined Experimental and Molecular Dynamics Study

“…In the heavy crude oil, the asphaltene component holds the major fraction . Asphaltenes form aggregates in n -alkanes, water, and water–oil emulsion and are responsible for the high viscosity of crude oil. , The chemical treatment of asphaltenes is done using cyclic aromatic compounds, such as benzene, toluene, xylene, and pyridine, in which asphaltene is soluble. These solvents are, however, hazardous and volatile.…”

Molecular Dynamics Study of Solvent Effect on the Structure and Characteristics of Asphaltene aggregates.

“…In their study, four different solvent mixtures were considered, their results showed that pure CO 2 enhances hydrogen bond formation and dipolar interaction between aggregating molecules. The aggregation behavior of Asphaltene in aqueous solution was studied by Vatti et al [23], in the study, Violanthrone-97 was considered as the model Asphaltene compound while three water models were considered. The results obtained from the study emphasized the importance of using appropriate water models in studying the aggregation behavior of Asphaltenes.…”