A novel counterion-coupled gemini (cocogem) surfactant, DBSJ, was synthetized via the 2:1 coupling reaction between 4-(2-dodecyl)benzenesulfonic acid (Lutensit A-LBS) and polypropyleneglycol-bis(2-aminopropyl) ether (Jeffamine D230). The surfactant had a polydispersity index of Mw/Mn = 1.04, as determined by electrospray-ionization mass spectrometry. The micellar properties of DBSJ in water were investigated in the temperature range 283-348 K by conductometry and titration microcalorimetry. The critical micelle concentration (cmc) of the cocogem was found to be more than 1 order of magnitude less than that of monomeric sodium 4-(2-dodecyl)benzenesulfonate (SDBS). The mean degree of dissociation in the temperature range studied proved to be alpha = 0.39. The calorimetric enthalpies of micelle formation agreed well with the enthalpies calculated via the van't Hoff relation. The cmc versus T curve passes through a minimum just below room temperature, after which the micelle formation changes from endothermic to exothermic. The Gibbs free energy of micelle formation was nearly constant as the temperature was increased, due to enthalpy/entropy compensation. The isotherm for DBSJ adsorption from aqueous solution onto sandstone was determined by continuous flow frontal analysis solid/liquid chromatography at 298 K and 60 bar. The adsorption of DBSJ on sandstone followed an S-type isotherm. Surface aggregation occurred over an extended range of concentration. Surface saturation was reached at a solution concentration more than 1 order of magnitude less than for monomeric SDBS. This finding is a point of concern in the chemical flooding of oil reservoir rocks to enhance oil recovery.

No abstract

We report on the inclusion complex formation of β-cyclodextrin (βCD) with a cocogem surfactant (counterion-coupled gemini surfactant; (bis(4-(2-alkyl)benzenesulfonate)-Jeffamine salt, abbreviated as ABSJ), studied by isothermal titration calorimetry (ITC) and surface tension (SFT) measurements. We measured the critical micelle concentration (cmc) of ABSJ in water by the two experimental techniques in the temperature range 283-343 K, and determined the thermodynamic parameters of the complex formation directly by ITC and indirectly by the SFT. The stoichiometry (N), the binding constant (K), and the enthalpy of complexation were determined, and the Gibbs free energy and the entropy term were calculated from the experimental data. A novel method is presented for the determination of N and K by using surface tensiometry.

Considering the common use of sheet filtration for clarification of fruit brandies, the aim of this study was to evaluate the influence of its application on the stability and composition of volatile compounds of apricot brandy after cold stabilisation. Cold stabilisation treatment involved holding of the brandy at -1?C during 24 hours. Five depth filter sheets with the nominal retention rate of 0.3 ?m, 0.5-0.7 ?m, 0.7-1.0 ?m, 1.0-2.0 ?m and 2.5-4.0 ?m, were tested in the study. It was shown that all assessed filter sheets were efficient in removing chill haze by significantly reducing the content of fatty acid esters (primarily ethyl palmitate and ethyl laurate). Other volatile and aromatic compounds were not significantly influenced by the applied treatments. However, the filter sheets with higher nominal retention rate (> 0.7 ?m), had a smaller impact on the sensory characteristics of the apricot brandy. The re-exposure to lower temperatures did not lead to chill haze formation in any sample obtained after sheet filtration. [Projekat Ministarstva nauke Republike Srbije, br. TR-31002]