How do ions contribute to brine-hydrophobic hydrocarbon Interfaces? An in silico study.

Autor: Badizad MH; Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran. Electronic address: mohammadhasan.badizad@che.sharif.edu., Koleini MM; Sharif Upstream Petroleum Research Institute (SUPRI), Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran. Electronic address: mmkoleini@che.sharif.edu., Hartkamp R; Process & Energy Department, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Leeghwaterstraat 39, 2628CB Delft, the Netherlands., Ayatollahi S; Sharif Upstream Petroleum Research Institute (SUPRI), Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran. Electronic address: shahab@sharif.edu., Ghazanfari MH; Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran.
Jazyk: angličtina
Zdroj: Journal of colloid and interface science [J Colloid Interface Sci] 2020 Sep 01; Vol. 575, pp. 337-346. Date of Electronic Publication: 2020 Apr 16.
DOI: 10.1016/j.jcis.2020.04.060
Abstrakt: Hypothesis: The saltwater-oil interface is of broad implication in geochemistry and petroleum disciplines. To date, the main focus has been on the surface contribution of polar, heavy compounds of crude oil, widely neglecting the role of non-polar hydrocarbons. However, non-polar compounds are expected to contribute to characteristics of oil-brine interfaces.
Methodology: Utilizing molecular dynamics simulation, we aim to characterize ion behavior adjacent to hydrophobic organic phases. Concerning natural environments, NaCl, CaCl 2 and Na 2 SO 4 electrolytes at low (5 wt%) and high (15 wt%) concentrations were brought in contact with heptane and/or toluene which account for aliphatic and aromatic constituents of typical crude oils, respectively. The reproduced experimental data for interfacial tension, brines density and ions' diffusivities adequately verify our molecular calculations.
Findings: Ions accumulate nearby the intrinsically charge-neutral oil surfaces. A disparate surface-favoring propensity of ions causes the interfacial region to resemble an electrical layer and impose an effective surface charge onto the oil surface. Despite absence of any polar site, the effective surface charge density is hydrocarbon-dependent, with the highest and lowest values observed for toluene and heptane interfaces, respectively. Due to accumulation of toluene molecules nearby the brines, the interfacial characteristics of heptol (toluene-heptane mixture) is comparable to that of the toluene phase.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2020 Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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