A green and easy synthesis method of catanionic surfactant ammonium benzenesulfonate and its surface properties and aggregation behaviors

Study on the Synthesis, Surface Activity, and Self-Assembly Behavior of Anionic Non-Ionic Gemini Surfactants

The use of surfactants in oil recovery can effectively improve crude oil recovery rate. Due to the enhanced salt and temperature resistance of surfactant molecules by non-ionic chain segments, anionic groups have good emulsifying stability. Currently, there are many studies on anionic non-ionic surfactants for oil recovery in China, but there is relatively little systematic research on introducing EOs into hydrophobic alkyl chains, especially on their self-assembly behavior. This article proposes a simple and effective synthesis method, using 3-aminopropane sulfonic acid, fatty alcohol polyoxyethylene ether, and epichlorohydrin as raw materials, to insert EO into hydrophobic alkyl chains and synthesize a series of new anionic non-ionic Gemini surfactants (CnEO-5, n = 8, 12, 16). The surface activity, thermodynamic properties, and self-assembly behavior of these surfactants were systematically studied through surface tension, conductivity, steady-state fluorescence probes, transmission electron microscopy, and molecular dynamics simulations. The surface tension test results show that CnEO-5 has high surface activity and is higher than traditional single chain surfactants and structurally similar anionic non-ionic Gemini surfactants. Additionally, thermodynamic parameters (e.g., ΔG°mic ΔH°mic ΔS°mic et al. indicate that CnEO-5 molecules are exothermic and spontaneous during the micellization process. DLS, p-values, and TEM results indicate that anionic non-ionic Gemini surfactants with shorter hydrophobic chains (such as C8EO-5) tend to form larger vesicles in aqueous solutions, which are formed in a tail to tail and staggered manner; Negative non-ionic Gemini surfactants with longer hydrophobic chains (such as C12EO-5, C16EO-5) tend to form small micelles. The test results indicate that CnEO-5 anionic non-ionic Gemini surfactants have certain application prospects in improving crude oil recovery.

Synthesis and physicochemical properties of sodium oleyl sulfate

In this paper, sodium oleyl sulphate (SOS) was successfully synthesised by reacting octyl alcohol (OA) with gaseous sulphur trioxide (SO3) as a sulphating reagent in a falling film reactor. The structure was determined by Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1HNMR) spectroscopy. The dynamic adsorption and aggregation behaviour of SOS was systematically investigated to reveal the relationship between the structure and properties of SOS. The physicochemical properties of SOS were determined by measuring the equilibrium surface tension, dynamic surface tension and dynamic contact angle, respectively. A laser particle size analyser and a transmission electron microscope (TEM) were used to analyse the aggregation behaviour of SOS. Compared to sodium dodecyl sulphate (SDS) and sodium n-octadecyl sulphate (C18H37OSO3Na), which have a similar structure to SOS, the increase in hydrophobic chain size and tighter molecular packing enabled by the polar head conformation caused a decrease in CMC and an increase in surface activity. The efficiency of the surface activity was controlled by a mixed diffusion kinetic adsorption mechanism. Moreover, SOS in aqueous solution showed efficient wettability on the surface of the low-energy paraffin film at concentration above the CMC. In addition, SOS molecules can spontaneously form spheroidal aggregates with increasing concentration, and the size of the aggregates increased with the concentration.

Synthesis and Properties of Novel Catanionic Surfactant Phosphonium Benzene Sulfonate

A new type of catanionic surfactant phosphonium benzene sulfonate was synthesized by quaternization of triphenyl phosphine with dimethyl carbonate and followed by anion exchange with alkyl benzene sulfonic acid. The molecular structure was characterized by FT-IR, 1H-NMR, and 31P-NMR. The thermal stability of phosphonium benzene sulfonate was evaluated by thermogravimetric analysis (TGA). Its surface properties were studied systematically through equilibrium surface tension, electrical conductivity, and dynamic surface tension measurements. The wettability, foam properties, and emulsification of phosphonium benzene sulfonate were estimated in this paper. TGA results revealed that it has an excellent thermostability and could be used below 350 °C. Equilibrium surface tension results indicated that it has a low critical micelle concentration (CMC, about 0.10 mmol/L), lower than that of ammonium benzene sulfonate and sodium dodecyl benzene sulfonate. Furthermore, the micellization of phosphonium benzene sulfonate in aqueous solution is an entropy-driven spontaneous process. The adsorption process of phosphonium benzenesulfonate at the air-liquid interface is controlled by hybrid kinetic adsorption. Moreover, it has excellent wetting and emulsifying properties and low foam properties.