Nowadays, constructing a mechanism to prevent the aggregation petroleum asphaltenes by the use of new acidic ionic liquids has become of fundamental importance. In this research, 3-(2-carboxybenzoyl)-1-methyl-1H-imidazol-3-ium chloride ([CbMIM] [Cl]) and other ionic liquids such as [CbMIM]BF4, [HMIM]Cl, [BMIM]Br, and [HMIM]HSO4 were tested. It should be noted that during the experiment the presence of the acidic ionic liquid moiety enhanced interactions between asphaltenes and acidic ionic liquids and it greatly limited asphaltene aggregation. We considered parameters such as temperature, amount of dispersant, effect of water: toluene ratio, the stirring time and effects of other ionic liquids, and determination of concentration of petroleum asphaltenes after dispersing by acidic ionic liquid under various parameters using UV-Visible spectroscopy. 1. Introduction Asphaltene is defined as a component of the crude oil which is precipitated by adding low molecular weight solvents (n-alkanes) [1]. According to recent studies, asphaltenes are defined as solid soluble asphaltenes in aromatic solvents (e.g., benzene/toluene) and are also regarded as insoluble asphaltenes in paraffinic solvents (n-heptane/n-pentane/petroleum ether, etc.) [2]. Asphaltenes are petroleum hydrocarbons with extremely complex molecular structure containing sulfur (0.3–10.3%), oxygen (0.3–4.8%), nitrogen (0.6–3.3%), and metal elements, such as Fe, Ni, and V in a small amount [3–6]. One of the most important problems in oil industries is the precipitation of heavy components of crude oil such as asphaltenes. The precipitation of these compounds causes different problems like the blockage of crude oil extraction in transport pipes and pollution of ecosystems [7, 8]. The aromatic moiety, through π-π* and dipole interactions, was thought to be one of the dominant contributors to asphaltene self-association. Hence, proper characterization of the asphaltene molecular structure and its aromaticity is fundamental in understanding of the self-association phenomenon [9]. The efficiency of dispersants is dependent on their polarity and structure. Therefore, dispersants should have an affinity to asphaltenes and should either be absorbed on the surface of the asphaltene aggregation or become bond with the polar group of asphaltene molecules [10]. Recent studies show that the petroleum asphaltenes are strong hydrogen bond acceptors and weak hydrogen bond donors [11]. However, strong acids become effective asphaltene dispersants if their alkyl tails are long enough to provide the necessary
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