Abstract:

Janus-SiO₂ nanoparticles were prepared by Pickering emulsion templating method by using 3-（2-aminoethylamino）propyltrimethoxysilane and n-octyl trimethoxysilane. The results of FT-IR, TG, contact angle and Zeta potential confirmed the successful grafting of amino groups and octyl groups onto the surface of SiO₂ nanoparticles. Considering the emulsion droplet diameter and emulsification index, the optimal emulsification conditions were obtained at a homogenization intensity of 15 000 r/min, Janus-SiO₂ nanoparticle mass fraction of 1.0%, and water-to-oil volume ratio of 5∶5. The average droplet diameter of the Pickering emulsion thus obtained was approximately 56.6 μm. The Janus-SiO₂ nanoparticles exhibited good emulsification performance, which could stabilize high internal phase emulsion and have low-energy emulsification and broad oil phase universality. The results of stability test demonstrated that the Pickering emulsion prepared remained stable at room temperature for more than two months and maintained stability in the temperature range of 4 to 90 ℃. The Pickering emulsion could be formed even when the aqueous phase had low or high pH or high mass concentrations of NaCl, indicative of excellent resistance to acid, base and electrolyte. In addition, the viscosity of the emulsion increased with increasing electrolyte mass concentration. The O/W Pickering emulsion stabilized with Janus-SiO₂ particles exhibited remarkable stability, which had potential for applications in cleaning of oil stains under high-temperature and high-electrolyte conditions.

Key words: Janus-SiO₂ particle, Pickering emulsion, high stability, pH-resistant, electrolyte-tolerance