Ionic Liquids Derived from Proline: Application as Surfactants

Abstract

Ionic liquids derived from prolinium esters, previously described as fully green and stable, were found to decompose in the presence of water by ester hydrolysis. To avoid this problem, a new family of these biodegradable salts incorporating an alcohol instead of the ester group is proposed. From this family, two novel ionic liquids that incorporate the prolinolium cation [HOPro] and the [DS] or [DBS] anion were selected (DS=dodecylsulfate; DBS=dodecylbenzenesulfonate). Both salts are liquid at room temperature, a property not usually found in ionic surfactants, and are also chemically and thermally stable. Moreover, they are more effective in reducing the surface tension of water than the corresponding traditional surfactants in the form of sodium salts, being useful for applications related to their aggregation capacity. They were tested for surfactant enhanced oil recovery and an optimal formulation for reservoirs at high salinity and temperature, able to produce ultra-low interfacial tension, was found with [HOPro][DBS].

Synthesis and Characterization of Surface‐Active Ionic Liquids Used in the Disruption of Escherichia Coli Cells

“…A number of ILs containing long alkyl chain substituents (typically more than eight carbons – octyl chains) have been reported to be surface‐active (or tensioactive). These ionic compounds are currently termed as surface‐active ionic liquids (SAILs) and are attracting increased interest in classical colloid and surface chemistry research . As the conventional surfactants, SAILs have the capacity to self‐aggregate in aqueous media above their critical micelle concentration (CMC) .…”

“…Recently, a new family of biodegradable SAILs composed of a cation derived from prolinium esters and dodecylsulfate and dodecylbenzenesulfonate anions was proposed . These SAILs proved to be more effective in reducing the surface tension of water than the respective sodium salts, being promising candidates for enhanced oil recovery applications . Although the phenomena of IL self‐organization in aqueous solutions are currently under investigation by a number of authors, their correlation with ILs structure is limited ,.…”

“…These ionic compounds are currently termed as surface-active ionic liquids (SAILs) and are attracting increased interest in classical colloid and surface chemistry research. [8][9][10][11][12][13][14][15][16] As the conventional surfactants, SAILs have the capacity to selfaggregate in aqueous media above their critical micelle concentration (CMC). [17] Due to their tunable structure, these compounds allow to design many new families and types of surfactants.…”

“…A number of analytical applications have emerged in separation science regarding the use of SAILs, not only as solubilization media for proteins, [18] and cell disruption, [19,20] but also in analytical techniques, namely chromatography or electrophoresis, [21][22][23][24] in biocatalysis [25] and also in extractive, preconcentration and recovery techniques. [11,26,27] The potential industrial application of SAILs, as well as their impact on the environment, is closely dependent on their self-assembly behavior and aggregate structure in aqueous solution. [28] Thus, the study of the aggregation behavior of these compounds in water is of high importance.…”

“…[11] These SAILs proved to be more effective in reducing the surface tension of water than the respective sodium salts, being promising candidates for enhanced oil recovery applications. [11] Although the phenomena of IL self-organization in aqueous solutions are currently under investigation by a number of authors, their correlation with ILs structure is limited. [36,[46][47][48] This lack of information is limiting their study and compromises the development of potential industrial applications.…”