Volume 54, Issue 5

The aim of the study presented in the paper was to demonstrate that using a combination of glycerin and surfactants in the form of sodium salts in the production of laundry liquid detergents might be an alternative to the currently commonly produced products based on surfactants in the form of potassium or triethanol ammonium salts. Tests were performed to determine functional standard properties of model liquid laundry detergent formulations with different contents of glycerin. The analysis focused on foaming power, rheological properties, solubility, washing ability and decrease in fabric strength after washing. The most beneficial functional properties, comparable to those found in formulations containing potassium or triethanol ammonium salts, were achieved at the glycerin content of 20%.

Solubilisation of pyrene (PAHs) in aqueous micellar solutions of natural surfactant saponin and conventional surfactant sodium dodecylbenzene sulfonate (SDBS) has been examined by UV-Vis and steady state fluorescence spectrometry at 30°C. The effect of addition of common salt NaCl on the I 1 /I 3 of fluorescence has also been determined. The experiment concludes that the pyrene molecules were incorporated in the palisade layers of both micelles because of their hydrophobic character. The interaction of pyrene with a neutral saponin micelle resulted in a red shift of UV absorption spectra, while the negative headed surfactant SDBS showed no such phenomena. The resulting thermodynamic parameters proved the better efficiency of the bio-surfactant saponin for the solubilization of pyrene with respect to that of the conventional surfactant SDBS. With increasing ionic strength (on addition of NaCl) the solubilization of pyrene was found to be better and effective in both the surfactant mediums.

Surfactants used in road surface treatments have an optimal application pH value which is an important condition for applications, otherwise stable bitumen emulsions with high solid contents are impossible to achieve. Therefore, a wide range of pH values were employed to investigate its effect on the bitumen/water interfacial properties of a cationic bitumen emulsifier. It is shown that interfacial tension and dilatational modulus have correlations with pH value. The lowest value of interfacial tension declined with the decrease of pH value. The strong acid system has the highest dilatational modulus while this modulus of the neutral system is the lowest. Compared with the neutral system, the maximum of the dilatational modulus also appears in the acid or alkaline system at a relatively low concentration. Physical properties of bitumen emulsions, including storage stability and Zeta potential, show the same changing rule as the interfacial rheology.

The interaction of fatty acid of Morinda citrifolia L. (FAMC) with ink was studied using Hele Shaw Cells. The interaction is compared to that of fatty acid derivates of synthetic surfactant. These interactions are modeled and explained through micro diffusion and its viscous fingering character. The results show that the molecule structure and the number of double bonds have a special effect on the surface tension and the micro diffusion character. FAMC at six-hour extraction has the highest speed of interaction and highest perimeter of diffusion among synthetic surfactants and other fatty acids in Morinda citrifolia L.

The influence of vitamins B 1 (thiamine hydrochloride), B 6 (pyridoxine) and B 12 (cyanocobalamine) on the micellization, surface activity and viscometric behavior of anionic surfactant sodium dodecylsulfate, cationic surfactant cetylpyridinium bromide and nonionic surfactant hexadecylpoly[oxyethylene(20)] alcohol at different temperatures was studied. The critical micelle concentration, the micellization thermodynamics, the maximum adsorption density, the standard free energy of adsorption and the other micellar parameters of surfactants in the presence of vitamins B 1 , B 6 and B 12 were obtained. On the basis of dependence of the relative viscosities on concentration, the viscosity B-coefficients of the Jones-Dole semiempirical equation were calculated for both premicellar and postmicellar regions. The results of our study allowed the conclusion that vitamins B 1 , B 6 and B 12 are solubilized in micelles.

The effects of oil-water ratios (α) on the composition of the balanced interfacial layer and the optimum solubilization of microemulsions C 16 mimBr/butan-1-ol/oil (octane, decane, dodecane)/5% NaCl solution were investigated. As α increases, the alcohol solubility in water and oil phases (S a ) in the microemulsions also tends to increase. The reason is the relatively high solubility of the alcohol in the oil phase compared to the solubility in water. When α increases, the number of surfactant (nss${\rm{n}}_{\rm{s}}^{\rm{s}}$) and co-surfactant (nas${\rm{n}}_{\rm{a}}^{\rm{s}}$) molecules required to balance the interface layer and the proportion of alcohol in the interfacial layer (A S ) increase but the solubilization capacity (SP*) decreases. When the total mass of water and oil is unchanged, the solubilization capacity of the microemulsion systems is lower the higher the relative content of oil is. The effects of different oils, salinity and temperature on the composition of the balanced interfacial layer and the solubilization of microemulsions were also investigated.

The present work deals with the physiochemical properties of polyoxyethylene sorbitan fatty acid esters (polysorbates), which are commonly known under the trade name Tween. Thermodynamics of micellization and adsorption at air-water interface for these nonionic surfactants solutions have been studied over a broad range of temperature. As the temperature of the surfactant solutions increases, the surface tension decreases whereas the critical micelle concentration (CMC) of each surfactant solution initially decreases and then increases. The free Gibb free energies of the micelle formation ΔGmo$\Delta {\rm{G}}_{\rm{m}}^{\rm{o}}$, and the surfactant adsorptionΔGadso$\Delta {\rm{G}}_{{\rm{ads}}}^{\rm{o}}$, are calculated for the CMC of each surfactant at different temperatures. The surface or expanding pressure (Π cmc ), minimum area per molecule (A min ), maximum surface excess (Γ max ) are also calculated. The interfacial tension (IFT) between the aqueous surfactant solutions and the crude oil are measured at different concentrations of the surfactants using a spinning drop tensiometer. The contact angles are determined on an oil wet quartz surface to investigate the wettability alteration in the presence of Tween surfactants with varying salinity. FTIR analysis of quartz at dry and oil wet state, crude oil and COBRS (crude oil-brine-rock-surfactant) combinations are performed to identify the associated functional groups and their mutual interactions.

A novel cationic Gemini surfactant with bis-piperidinium and benzene ring (C 10 -CGP) was synthesized by aniline, epichlorohydrin and 1-bromodecane in three steps. The structure of C 10 -CGP was characterized by mass spectroscopy (MS) and nuclear magnetic resonance ( 1 H NMR). The critical micelle concentration ( CMC ) and the corresponding surface tension ( γ CMC ) of C 10 -CGP were measured from 298 K to 313 K and the thermodynamic parameters of the micellization were calculated. The results showed that the critical micelle concentration ( CMC ) and γ CMC were 0.976 × 10 −3 mol · L −1 and 28.93 mN · m −1 at 298 K, respectively. With the temperature increase, the CMC increased, the maximum surface adsorption capacity ( Γ max ) decreased, the γ CMC decreased and the minimum molecule area ( A min ) increased. The free energy of the system during the micelle formation was negative. When the Gemini surfactant was used as an asphalt emulsifier, C 10 -CGP exhibited good a emulsifying ability. C 10 -CGP is a slow-set asphalt emulsifier.

Three series of cationic gemini surfactants were prepared and characterized using elemental analysis and 1 H-NMR spectroscopy. The surface properties of them, critical micelle concentration (CMC), surface excess concentration (Γ max ) and minimum surface area per molecule (A min ) were evaluated via surface tension measurements. Quantum chemical parameters, such as the energy of the highest occupied molecular orbital (E H ), the energy of the lowest unoccupied molecular orbital E L , the energy gap (ΔE g ), dipole moment (μ), electronegativity (χ), hardness (η), electrophilicity (ω), hydrophobicity (Log P), approximated surface area (A) and the total energy of the optimized structure (ΔE T ), were theoretically calculated using the MNDO method.

A simple method to prepare cobalt nanoparticles (CoNPs) in an aqueous environment was developed utilizing 4-aminophenol as a reducing agent and the gemini surfactant (14-4-14)/polyvinylpyrrolidone (PVP) as a stabilizer. The localized surface plasmon resonance band of cobalt nanoparticles in the UV-Vis spectrum was used to determine the rate of formation of cobalt nanoparticles and to assess the beginning of the oxidation process. The effect of the concentration cobalt nitrate, 4-aminophenol, 14-4-14 and PVP was investigated on the growth rate of CoNPs. The data obtained in this work provide valuable information on the rate of reaction at the nanoscale.