span style="font-size:11.0pt;mso-bidi-font-size: 14.0pt;font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:Mangal;mso-ansi-language:EN-US;mso-fareast-language:EN-US; mso-bidi-language:HI" lang="EN-US"Synergistic interactions in W/O microemulsions containing imidazolium based Csub12/submimBr and sodium lauryl sulfate/span

摘要

The physicochemical properties and synergistic effects of W/O microemulsion systems containing imidazolium based surfactant, 1-dodecyl-3-methylimidazolium bromide (Csub12/submimBr)-sodium lauryl sulfate (SLS)/ alcohol/alkane/5% NaCl solution at different molar ratios of water-to-surfactant (?sub0/sub) are studied. The W/O microemulsions are formed at the molar fractions of SLS-to-Csub12/submimBr+SLS (XsubSLS/sub) ranges of 0.0-0.3 and 0.7-1.0. The synergism between Csub12/submimBr and SLS can be seen from the values of iX/isubsubimg src='http://www.niscair.res.in/jinfo/avalue.gif' border=0/sub/sub(mole fraction of alcohol in the oil phase), Xsubsubimg src='http://www.niscair.res.in/jinfo/ivalue.gif' border=0/sub/sub(mole fraction of alcohol in the interfacial layer) and -iG/isubsubimg src='http://www.niscair.res.in/jinfo/o.gif' border=0/sub/subsub??ii/i/sub (the standard free energy change of transferring alcohol from the continuous oil phase to the interfacial layer). The increase in the values of iX/isubsubimg src='http://www.niscair.res.in/jinfo/avalue.gif' border=0/sub/sub and Xsubsubimg src='http://www.niscair.res.in/jinfo/ivalue.gif' border=0/sub/sub, and the decrease in -iG/isubsubimg src='http://www.niscair.res.in/jinfo/o.gif' border=0/sub/subsub??ii/i/sub values with ?sub0/sub is attributed to the increasing hydrophilicity of the microemulsions. By increasing the carbon chain lengths of the alcohol molecules, or by increasing the salt concentrations, the values of iX/isubsubimg src='http://www.niscair.res.in/jinfo/avalue.gif' border=0/sub/sub and Xsubsubimg src='http://www.niscair.res.in/jinfo/ivalue.gif' border=0/sub/sub decrease, whereas that of -iG/isubsubimg src='http://www.niscair.res.in/jinfo/o.gif' border=0/sub/subsub??ii/i/sub increases for the W/O microemulsions containing the mixed surfactants. On the other hand, the effect of the alkane carbon chain lengths is exactly the effect of the alcohol carbon chain lengths on the these parameters.