Pickering Emulsion of Water-In-Trichloroethylene Stabilized by Monodisperse Carbon Spheres

The ability of colloidal particles to solubilize two mutually immiscible fluids and form stable emulsions is known for over a century. In recent years, particle stabilized emulsions have been used to develop novel applications ranging from the synthesis of Janus particles and colloidosomes to drug delivery and catalysis at interfaces. The self assembly of micro and nanoparticles at interfaces is also of much interest from the perspective of creating building blocks for hierarchical structures. This work focuses on studying the interfacial behavior of monodisperse sub-micron carbon spheres synthesized using hydrothermal method that allows size control. Surfactant-free stable emulsions of water-in-trichloroethylene (TCE) were formed using the sub-micron size monodisperse carbon particles. The choice of oil phase is based on the convincing applicability of carbon spheres in environmental remediation. The emulsion phase was observed to be stable for months. The carbon particles reduce the interfacial tension between water and TCE by adsorbing irreversibly at the oil-water interface. Cryo Scanning Electron Microscopy shows that the formation of a particle bilayer between water droplets in the emulsion phase is key to the stability of the emulsion.