Evaluation of oil-in-water emulsions with cationic–anionic surfactants mixtures for potential use in the oil industry

The Influencing Factors and Mechanism of Anionic and Zwitterionic Surfactant on Viscosity Reduction in Heavy O/W Emulsions

The high viscosity of heavy crude oil has been an obstacle to its safe production and economic transportation. In this work, a screened emulsified viscosity reducer system is conducted. Experimental results demonstrate that the most effective viscosity reducing agent comprises sodium oleate (NaOl) and cocamidopropyl betaine (CAB-35) in a ratio of 1:2, achieving a viscosity reduction rate of 94.65%. Additionally, the interfacial tension between oil and water decreases from 27 to 4 mN/m with 0.1 mass % TEOA and NaOH in a 1:1 ratio. The oil droplet size is uniformly distributed with D mean is 14 μm and D 50 is 11 μm. Droplets flocculate as the salinity increases to 0.2 mol/L, which corresponds to the apparent increase of viscosity. The adsorption of long alkyl chain lipophilic groups on surfactant molecules at the oil-water interface and the water film alters the wettability of pipe steel to water-wet, further enhancing the application of emulsification and viscosity reduction effects. The primary mechanism behind the viscosity reduction in emulsification is attributed to strong electrostatic interactions stemming from molecular electrostatic potential distributions.

Thermodynamic characterization of a non-commercial emulsifying agent for asphalt emulsion

The objective of the present work was to characterize a non-commercial emulsifying agent: dodecylpyridinium thiocyanate (C12PCNS). This study was carried out by conductimetry technique in the temperature range 25-50 °C. Assuming the system conforms to the pseudo-phase separation model, change of standard Gibbs free energy, ΔG_m⁰, enthalpy, ΔH_m⁰, and entropy of micellization, ΔS_m⁰, were estimated. Values for critical micelle concentration (cmc) and the ionization degree, β, were determined directly from the experimental data. The results show that the influence of the counter ion is very relevant, because the cmc for this compound is appreciably greater than the cmc of other pyridinium homologs of the same chain length. Finally, the compensation rule for this system has been found and the compensation temperature and the intercept ΔH^*-it is an indication of the stability of the micelle-were estimated.

An Evaluation of the Physicochemical Properties of Stabilized Oil-In-Water Emulsions Using Different Cationic Surfactant Blends for Potential Use in the Cosmetic Industry

One of the most complex problems in hair care formulations is the duality of the surfactants used. In this regard, such surfactants must be cationic so as to interact with the negatively charged cuticle surface of hair. However, these interdependencies typically lead to non-ideal values for the required hydrophilic–lipophilic balance (HLB) in the oil phase. This study was designed to evaluate the physicochemical properties of several oil-in-water emulsion prototypes for the potential use in hair conditioners. Here, a base formulation was utilized, incorporating binary mixtures of cationic surfactants in different proportions. The cationic surfactants employed were hydroxyethyl-behenamidopropyl-diammonium chloride, behentrimonium methosulphate, cetrimonium chloride, and (iv) Polyquaterniumpolyquaternium-70. The surfactants were evaluated for their capability to decrease the surface tension in an aqueous solution through contact angle measurements between the oily phase and the aqueous phase. The required HLB of the oil phase was also determined. The emulsification process was developed using standard preparation methods. For three months, the prototypes with high viscosity were packed in containers and stored in a stability chamber at accelerated conditions (40 ± 2 °C and 75 ± 5% RH). During this time, the size, size polydispersity, zeta potential, viscosity, rheological profile, and creaming index were all evaluated monthly. The results showed a slight change in the physical stability of the prototypes, where the droplet size increased moderately, however, did little to destabilize the formulations. This suggests that the mixtures of cationic surfactants used could be useful for technological developments in hair conditioning products.

Synthesis and Characterization of Biguanide and Biguanidium Surfactants for Efficient and Recyclable Application in the Suzuki-Miyaura Reaction

We report here the synthesis and thorough characterization of a new family of alkylbiguanides and alkylbiguanidium chlorides by ¹H and ¹³C NMR and X-ray diffraction. Their critical micelle concentration was first determined by surface tension measurements. Hexylbiguanide was then studied as a surfactant in the micellar Suzuki-Miyaura cross-coupling reaction. The unexpected low reactivity of the system at high Pd/hexylbiguanide ratios was due to the change of the size and the shape of the aggregates, observed by transmission electron microscopy. The best catalytic activity was obtained for a 1:1 Pd/hexylbiguanide ratio for which the micellar conditions were conserved. Better results were obtained for several substrates, when compared to those previously obtained with metformin under the same reaction conditions. Higher yields and a better recyclability were obtained under micellar conditions with hexylbiguanide.