Study On The Synthesis And Physicochemical Properties Of Anionic-Nonionic Surfactants

The interfacial properties of Anionic-nonionic surfactants are favourable because the molecules of such surfactants contain both oxyethylene (EO) units and anionic group as their hydrophilic group, so they can be widely used in Enhanced Oil Recovery (EOR), especially in oil well of high salt content. Up to now the studies in this field are mainly focused on those Anionic-nonionic surfactants with fat chain as their hydrophobic group, and investigations of the Anionic-nonionic surfactants having phenyl as hydrophobic group have scarcely been made. Therefore, it is valuable to carry the research on this subject. In the dissertation, two types of Anionic-nonionic surfactants with phenyl, sodium alkylphenylene homogeneous polyoxyethylene ether carboxymethylates (abbreviated as APEC) and sodium p-(n-alkyl)-benzyl homogeneous polyoxyethylenated propane sulfonates (abbreviated as ABEPS), were synthesized. The water-solubility, surface/interface properties, foam properties and bulk phase properties were studied. A series of valuable research results were gained as following:The APEC were prepared from phenol and long chainα-alkene by the procedure of Friedel-Crafts alkylation, Williamson and carboxymethylated reaction. From the study on the physicochemical properties, it was shown that APEC had good water-solubility ability and favorable surface performance, and salt resistance of such surfactants was greatly outstanding, furthermore ultra low interfacial tension could be achieved with proper amount NaCl in the water-crude oil system, however, the foaming performance were not good.A series of ABEPS were synthesized from long chain fatty acids, benzene, polyglycol and 1, 3-propane sultone by the procedure of Friedel-Crafts acylation, Huang-Minlon reduction, Williamson and sulfonation reaction, and these compounds had never been reported in the past time. Their structures were identified by ESI-MS, 1H NMR and Elementary Analysis. The mass fractions of active substances in the products, determined by two-phase titration, were all above 99.2%.The ABEPS were selected as model compounds to study the effect's of the length in hydrophobic group and the number of EO units in hydrophilic group on their physicochemical properties. The surface tensions of ABEPS were investigated in NaCl solutions at 30℃and in aqueous solution at different temperature. The values of critical micelle concentration (CMC), surface tension at CMC (γCMC), efficiency in surface tension reduction (pC20), saturation adsorption amount (Γmax), the values of HLB, standard free energy of adsorption (⊿G0ad), and of micellization (⊿G0mic) were obtained by theseγ-log C curves. It was discovered that the length in hydrophobic group and the number of EO units in hydrophilic group of ABEPS influenced profoundly on the adsorption at the gas-water interface and surface properties. According to the definition of effective carbon atom number, the difference in interfacial properties between ABEPS and accustomed ionic, nonionic, other Anionic-nonionic surfactants were discussed in detail on the view of molecular structure. It is worth noting that ABEPS have some character of both nonionic and ionic surfactants.The interfacial tension between ABEPS solution and crude oil had been investigated. It was shown that ABEPS not only displayed outstanding salt resistance, but also good hard-water endurability, furthermore ultra low interfacial tension could be achieved without alkaline but proper amount NaCl in the water-crude oil system, which proved its excellent interfacial performance and better application prospects.The bulk phase properties of ABEPS were investigated Fluorescence Probe technique. The influence of the length of alkyl chain in hydrophobic group on CMC, micelle aggregation number, and micelle micropolarity were discussed. It was found that the CMC value and micelle micropolarity decreased, micelle aggregation number increased as the length of alkyl chain increased. Moreover, it was discovered that the micelle aggregation number of ABEPS changed clearly with the concentration in the bulk.The foam properties of ABEPS in the aqueous solution at different physicochemical condition (such as the concentration of ABEPS, temperature, salt, etc.) were measured by air flowing method. It was found that ABEPS displayed fine foaming performance, and foaming performance of ABEPS was greatly better than that of APEC. The foaming ability increased as the temperature rose, while the foaming stability showed opposite tendency. The alkoxyamide additive increased the foam stability evidently.The contents of this dissertation provide the related academic and experimental foundation for molecular design of high performance oil-displacing surfactant system.