A novel polyamine microsphere, prepared from the water-in-oil emulsion of polyethylenimine, was characterized. The investigation of scanning electron microscopy showed that the polyamine microsphere is a regular ball with a smooth surface. The diameter distribution of the microsphere is 0.37–4.29 μm. The isoelectric point of the microsphere is 10.6. The microsphere can adsorb proteins through the co-effect of electrostatic and hydrophobic interactions. Among the proteins tested, the highest value of adsorption of microsphere, 127.8 mg·g⁻¹ microsphere, was obtained with lipase. In comparison with other proteins, the hydrophobic force is more important in promoting the adsorption of lipase. The microsphere can preferentially adsorb lipase from an even mixture of proteins. The optimum temperature and pH for the selective adsorption of lipase by the microsphere was 35 °C and pH 7.0.

A new hydrophobic surfactant, dodecyl lauroyl benzene sulfonate (DLBS), was synthesized and its application in enhanced oil recovery by alkali-surfactant-polymer (ASP) flooding was studied. The results show that DLBS can be synthesized by reaction of industrial dodecyl benzene with lauroyl chloride in the presence of AlCl₃, followed by sulfonation with ClSO₃H and neutralization with NaOH. The lauroyl-group is confirmed to be connected to the para-position of the alkylbenzene by ¹HNMR spectrum. The synthesized DLBS is well soluble in pure water and reservoir (connate) water at 45°C. It is highly surface active which is indicated by its low CMC of 1.1 · 10⁻⁵ mol/L, and its low surface tension, γ_cmc of 28.6 mN m⁻¹. By mixing with heavy alkylbenzene sulfonates of relatively low average molar mass (387 g mol⁻¹) at a total surfactant concentration of 5 mM, DLBS can reduce the interfacial tension of Daqing crude oil/connate water to an order of 10⁻³ mN/m at 45°C in the presence of 0.5–1.0 wt.% NaOH and 1000 mg L⁻¹ of polymer. If the NaOH was replaced by a gentle alkaline salt, Na₂CO₃, certain amounts of dodecyl dimethyl carboxy betaine were added and the concentration of Na₂CO₃ was increased to 1.2–2.0 wt.%, the interfacial tension of Daqing crude oil/connate water can also be reduced to an ultralow value. Therefore DLBS is a good hydrophobic surfactant applicable in ASP flooding with either NaOH or Na₂CO₃ as alkaline agents.