Hydrophilic TiO₂@MXene membrane for direct generation of monodisperse submicron water-in-diesel emulsion and its microexplosion performance

Hydrophilic membrane interfaces, especially that of particle-packed ceramic membranes, are generally not suitable for use as emulsification media for generating monodisperse water-in-oil emulsions. This is because their short adjacent pore distances tend to cause droplet coalescence. In this study, a facile in situ oxidation strategy was proposed to develop ceramic-based hydrophilic TiO2@MXene membranes for directly generating mono-disperse submicron water-in-diesel emulsions using membrane emulsification technology at room temperature. Through the in situ oxidation process, numerous TiO2 nanoparticles were grown on the surface of MXene nanosheets to form a novel TiO2@MXene composite structure with a membrane pore size of 12.2 nm. This structure is characterized by abundant transport channels, remarkably robust stability, and high water permeance of 154.8 L m(-2) h(-1) bar(-1). Because of the long horizontal distance between adjacent nanosheets and the substantially reduced transport resistance, water droplets can roll smoothly along the TiO2@MXene nanochannels and then converge with the diesel, thus reducing the risk of emulsion coalescence. The mean droplet size of the emulsions can be controlled from similar to 100 to 500 nm by regulating the emulsification conditions. The optimal emulsions exhibited excellent monodispersity with an average droplet size of 157.2 nm and possessed relatively excellent long-term stability (up to 45 days). Moreover, the emulsions showed a positive microexplosion phenomenon during heating. The maximum microexplosion strength of the emulsions reached 6.31 m s(-1) (at 20% water content), which provides a reliable theoretical basis for research on emulsified diesel as an alternative to traditional fuels.