pH and Temperature Effects on the Enhanced Oil Recovery with Gemini Ionic Liquids

By growing the demand of energy in the world, attempts to develop new methods in enhanced oil recovery wereincreased. Among them, chemical enhanced oil recovery (CEOR) methods, with impressive impacts, become moreappealing. In other hand, gemini ionic liquids (ILs) are environmentally friendly compounds with high surface/interfaceactivity. In this contribution, current study explores the performance of a homolog series of gemini imidazolium ILswith different alkyl chain lengths, [Cnim-C4-imCn]Br2, n = 4, 8, and 12, for reducing crude oil-water interfacial tension(IFT). In this regard, the influence of pH (within 2.5 - 9.5) and temperature (within 298.2 - 328.2 K) as crucial unitoperation parameters were considered. Results showed a drastic IFT reduction in the presence of ILs to the extent of72.3, 97.8, and 99.97%, respectively, for n = 4, 8, and 12. Results also demonstrate a remarkable synergism byincreasing pH, that causes the maximum IFT reduction to the extent of 49.5, 43.1, and 80.3%, for n = 4, 8, and 12. Thegreater performance of the ILs with pH can be attributed to the hydroxyl ions (OH−) adsorption at the interface andneutralizing electrostatic repulsion between the ILs head groups. Meanwhile, micelles are formed at lowerconcentrations as pH increases. Also temperature intensified IFT reduction by weakening the molecular forces betweenphases. The maximum decrease with temperature was about 12.4, 15.2 and 55.7%, for n = 4, 8 and 12, respectively.

Keywords:

Gemini ionic liquids , Interfacial tension , Enhanced oil recovery , pH , Temperature