Abstract
The demulsification of model water-in-oil (w/o) emulsions containing 1% wt. water by [Omim][PF6] and Aliquat® 336 ionic liquids (IL) as demulsifiers was investigated in batch mode at different temperatures (30, 45 and 60 °C) and demulsifier concentrations (2.5×10‒3, 1.2×10‒2 and 2.9×10‒2 mol L‒1). The model oil is a mixture n-heptane/toluene (70/30% wt.) with 1% wt. of Span® 83 as a surfactant. Experimental results showed that the main differences in demulsification dynamics between systems containing IL and blank (i.e., in the absence of demulsifier) are detected at 30 °C and for short demulsification times (t≤4 h). In particular, the demulsification efficiency is 8, 21 and 74% for the blank sample, [Omim][PF6] and Aliquat® 336 tested under the more concentrated IL condition, respectively. The superior demulsification performances of Aliquat® 336 with respect to [Omim][PF6] were related to the greater molecular weight and more hydrophobic character of its cation, likely able to induce a faster desorption of the surfactant at the w/o interface and consequently promoting water droplet coalescence. Moreover, the kinetic demulsification data were successfully interpreted by an empirical pseudo-first order model. In general, the obtained outcomes encourage future research efforts in the use of ionic liquids for the removal of low water fractions from w/o emulsions.
Highlights
The formation of water-in- oil (w/o) emulsions is a critical issue in industrial applications such as the petroleum sector
This paper aims at providing a contribution in the assessment of the applicability of ionic liquids for separating w/o emulsions with low water content, by adopting a model emulsified system as a first stage of investigation
The results clearly testify that both the tested ionic liquids (IL) are effective in inducing a higher water separation with respect to the blank sample, mainly at 30 °C and under more concentrated demulsifier conditions (i.e., concentration levels (CIL)=2.9×10‒2 mol L‒1)
Summary
The formation of water-in- oil (w/o) emulsions is a critical issue in industrial applications such as the petroleum sector. The formation of emulsions is promoted by the mixing in the equipment used in. Lancia fields (electrocoalescers), conventional heating and microwave demulsification, pH adjustment, membrane separation and chemical demulsification (Abdurahman et al, 2007; Djuve et al, 2001; Ekott and Akpabio, 2010; Guzmán-Lucero et al, 2010; Hajivand and Vaziri, 2015; Issaka et al, 2015; Yang et al, 2009). The mechanical separators and electrostatic grids commonly adopted for the destabilization of crude oil emulsions have high equipment volume and high cost for the installation on offshore platforms as main drawbacks (Ekott and Akpabio, 2010)
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