Abstract Nano-silica (Nano-SiO2) particles have some limitations in their application as an oil displacement agent due to the easy aggregation characteristics. Therefore, it is necessary to modify the particle surface to enhance its dispersibility. A silane coupling agent (KH570) was used to organically modify Nano-silica, the relationship between the dosage of KH570 with the zeta potential, contact angle, particle size, sedimentation rate of modified Nano-SiO2 particles before and after modification was studied. And a displacement system (KH570-G-Nano-SiO2/PS) was fabricated by compounding modified Nano-SiO2 particles with the petroleum sulfonate (PS) molecules, the interfacial tension, emulsification property of the system with crude oil were systematically investigated, finally the synergistic effect of modified particles on the reduction of interfacial tension was explored. Results showed that when the dosage of KH570 was 5 %, the wettability of the particles changed from hydrophilic to hydrophobic, and the dispersion stability was significantly improved. The modified Nano-SiO2 (0.2 %)/PS (0.3 %) system can reduce the oil/water interfacial tension to 5.42 × 10−3 mN/ m. At this point, zeta potential of the system was 54.8 mV, and the stability of the emulsion prepared by this system reached its best level. The modification of Nano-SiO2 particles and the mechanism of reducing the oil/water interfacial tension after compounded with petroleum sulfonate (PS) is analyzed. The modification degree of Nano-SiO2 particles has great influence on the interfacial tension of the system compounding with surfactant.

中文翻译：

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表面改性纳米SiO2及其与表面活性剂的结合对界面张力和乳液稳定性的影响

摘要 纳米二氧化硅（Nano-SiO2）颗粒由于具有易团聚的特性，在其作为驱油剂的应用中存在一定的局限性。因此，有必要对颗粒表面进行改性以提高其分散性。采用硅烷偶联剂（KH570）对纳米二氧化硅进行有机改性，研究了KH570用量与改性前后纳米SiO2粒子的zeta电位、接触角、粒径、沉降速率的关系。并通过改性纳米SiO2颗粒与石油磺酸盐（PS）分子复合制备驱替体系（KH570-G-Nano-SiO2/PS），系统研究了该体系与原油的界面张力、乳化性能，最后探讨了改性颗粒对降低界面张力的协同作用。结果表明，当KH570用量为5%时，颗粒的润湿性由亲水性变为疏水性，分散稳定性显着提高。改性的 Nano-SiO2 (0.2%)/PS (0.3%) 体系可将油/水界面张力降低至 5.42 × 10−3 mN/m。此时体系的zeta电位为54.8 mV，该体系制备的乳液稳定性达到最佳水平。分析了纳米SiO2颗粒的改性及与石油磺酸盐(PS)复合后降低油水界面张力的机理。Nano-SiO2粒子的改性程度对与表面活性剂复合的体系的界面张力有很大影响。