No abstract

As one important parameter for selecting surfactant used in chemistry flooding, here the interfacial tension (IFT) between crude oil and single surfactants Shengli petroleum sulfonate (SHL-PS), α-olefin sulfonate (C14/16AOS), fatty alcohol polyethyleneoxy ether sulfonate (CnEmSO) or their mixture using mimic Shengli brine water as solvent were investigated using spinning drop technology. The results showed: Through C18E3SO has a small ultra-low IFT window, it is more practical and efficient to obtain ultra-low IFT by mixing two or more surfactants other than using single surfactant; the length of hydrophobic tail plays a more important role than oxyethylene group number on the IFT for CnEmSO/SHL-PS; at mass ratio 1:19, both C14/16AOS/SHL-PS and C18EmSO/SHL-PS systems can lower the IFT to below 10−2 mN/m, but their mechanisms may be not same.

In this study, a cationic surfactant ion-selective electrode was prepared; its performance was determined. The electrode showed good Nernstian response to some kinds of cationic surfactants and had lower detection limits (10−6 mol/L order of magnitude). Potentiometric titration was employed to determine the concentrations of three cationic surfactants (DDMBAC, CTAB, OTMAC) using the electrode as indicator electrode and sodium tetraphenylborate solution as titrant. The titration results were satisfactory compared with the two-phase titration method. The relative errors between the electrode and two-phase titration were 2.12 %, 3.45 %, and 4.21 %, respectively. In addition, the electrode was used to determine the critical micelle concentration of cetyl trimethyl ammonium bromide (CTAB) in organic solvent/water, and the CMC measured using the electrode method was nearly identical with that measured using the conductivity method.

Cationic polyacrylamide (CPAM) was prepared in aqueous solution by free radical polymerization of methacryloyloxy ethyl trimethylammonium chloride (DMC) and acrylamide (AM). A redox initiator system was used. The structure of CPAM was characterized by IR and 1H NMR. The intrinsic viscosity and cationicity of CPAM were measured by an Ubbelohde viscometer and titration experiments, respectively. It was found that at the same concentration, the intrinsic viscosity decreases as the cationicity increases. The antistatic properties of CPAM on polyester fabric, the combability of hair, the flocculation on diatomaceous earth in a simulated sewage system and the thickening effect in solution were investigated. The results show that the higher the concentration, cationicity and intrinsic viscosity of CPAM, the better the thickening effect and the better the combability, the antistatic and flocculation properties. Therefore, the production of CPAM with high intrinsic viscosity and cationicity is important for an enhanced application performance.

Three cationic copolymers methacryloxyethyl trimethyl ammonium chloride-butyl acrylate-acrylamide (MTAC-BA-AM terpolymer) were designed and synthesized by emulsion polymerization. Their structures were confirmed by FT-IR and 1H NMR. The effect of content of hydrophobic monomer butyl acrylate (BA) in MTAC-BA-AM terpolymer on surface activities, flocculation and antibacterial properties were investigated. The study of surface tension shows that MTAC-BA-AM terpolymer has good surface activity due to the introduction of hydrophobic monomer BA. The flocculation experiment showed that the light transmittance of the kaolin suspension supernatant was 98.13% when the dose of MTAC-BA-AM terpolymer in the kaolin suspension was 0.03 mg/L, which was obviously better than the P(MTAC-AM) (91.02%) without hydrophobic modification of BA. The bacteriostatic experiment of MTAC-BA-AM terpolymer showed that as the content of hydrophobic monomer BA in MTAC-BA-AM terpolymer increased the inhibitory rate of MTAC-BA-AM terpolymer aginst Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus)