Pickering Emulsions Stabilized With Hydrophobic SiO₂ Particles

Pickering emulsion with solid particles as emulsifier has great potential in promoting mass transfer in gas-liquid-solid and liquid-liquid-solid multiphase systems.Because SiO₂particles are rich in hydroxyl groups,their surface properties can be controlled by surface grafting modification,which can be used in the preparation of Pickering emulsion.In this paper,the influencing factors of the hydrophobic modification of SiO₂ particles were quantitatively studied,and a prediction model for the type and stability of Pickering emulsion was proposed.（1）In this paper,a new surface modification process is proposed.The surface hydrophobic modification of SiO₂ particles is carried out by using a homogeneous reactor with its own rotating system.The hydrophobic organic groups are successfully grafted on the surface of solid particles to obtain solid particles with hydrophobic surface and realize the large-scale modification of solid particles.The effects of SiO₂ particle size and silane coupling agent type on the modification were studied.The quantitative relationship between the amount of silane coupling agent and wettability of particles was established,and the type of Pickering emulsion corresponded to the amount of silane coupling agent.（2）The adsorption mechanism and self-assembly behavior of solid particles at the oil-water interface during the formation of Pickering emulsion were determined by studying the oil-water system,the particle size of solid particles and the type of silane coupling agent.By theoretical analysis,the three-phase contact antenna was converted into the interfacial tension between solid-water,solid-oil and oil-water,and then the interfacial tension between solid-liquid was converted into intermolecular forces,and the intermolecular forces were calculated by DFT theory,which provided a feasible theoretical model for the preparation of different types of Pickering emulsion.（3）By analyzing the particle size distribution of Pickering emulsion droplets,the effects of solid particle additive amount,solid particle diameter,dispersed phase volume and continuous phase volume on the particle size of Pickering emulsion droplets were quantitatively studied.The kinetic and thermodynamic stability of Pickering emulsion was verified by the separation rate of continuous phase and the final stabilized Pickering emulsion volume.