Structural and Phase Behavior Studies of Pyridine and Alkyl Pyridine at the Interface of Oil/Water by Molecular Dynamics Simulation

Abstract

Polar fractions of crude oil play an important role in the state and structure of the oil/water interface, and understanding their behavior is crucially important in oil recovery. In studying different properties of oil/water interface, there are issues to be resolved and understood on the basis of molecular structure. A synthetic oil/water system is usually used to model and to simulate molecular-based behavior of the interface involving a polar surfactant. This paper is devoted to modeling the behavior of pyridine and its alkyl derivative at the interface of synthetic oil/water by molecular dynamics simulation. Solutions of pyridine and 4-ethylpyridine in octane/water system were studied for the density distribution and the structure in bulk phases as well as their molecular orientation at the interface. The interface of the octane/water system was first studied by simulation of density profile and interfacial properties to validate the force field applied. The distribution of pyridine and 4-ethylpyridine in and at the interface was studied, and the orientation of these molecules was determined accordingly. The results of simulation indicate that pyridine dissolves in water and avoids the interface leaving no residue in the octane phase, while 4-ethylpyridine mainly occupies the interface and dissolves partly in water. The bivariat maps gives molecular orientations in terms of spherical polar angles and indicate that the pyridine ring plane takes a parallel position with respect to interfacial plane surface; the nitrogen atom in pyridine takes any direction toward water and octane equally, but in 4-ethylpyridine preferentially is oriented toward water.

Molecular Dynamics Simulation Insight into Interfacial Stability and Fluidity Properties of Microemulsions

“…Molecular dynamics simulations have been used to investigate the oil/surfactant/water interfacial structure in previous work. − On the whole, our microemulsion systems are constituted of water, AOT, and n -heptane molecules, as heptane represents one of the most common oil components in the O–W interface study. − The interfacial properties are systematically studied at various concentrations of AOT molecules.…”

Vinylpyridines as Building Blocks for the Photocatalyzed Synthesis of Alkylpyridines

“…2‐Alkylpyridine alkaloids (e.g., phormidinine A, Figure ) were isolated from marine organisms as well . Substituted alkylpyridines were recently investigated for their peculiar umami flavor or as polar surfactants …”

“…[3i] Substituted alkylpyridines were recently investigated fort heir peculiar umami flavor [4] or as polar surfactants. [5] From as ynthetic pointo fv iew,v inylpyridines are useful substrates for the preparation of alkylpyridines through direct addition of nucleophiles onto the double bond. Differents trategies are known for the C-alkylation of ethenylpyridines by addition of C-nucleophiles (benzyl anions [6a] or enolate anions [6b-d] ), under reductive, [6e] acid-catalyzed, [6f] N-heterocyclic carbene-catalyzed, [6g] or metal-catalyzed [6h-j] conditions.…”

Molecular dynamics study of oil detachment from an amorphous silica surface in water medium

“…Some experiments on detachment of oil drops from silica substrate were carried out, and the mechanisms of oil detachment from substrate had been analyzed [4][5][6][7][8][9][10]. Recent papers [4,5] show findings that the detachment process of oil from silica surface involves three stages.…”

“…There are also some experiments where different organic pollution is used to do simulations. These involve the simulations about adsorption and detachment of oil on the solid surface [6][7][8][9][10][11][12][13]. The simulation objects of oil molecules include Pyridine and Alkyl Pyridine [9], dodecane [10], organic methanol [11] and so on.…”