Foaming of Oils: Effect of Poly(dimethylsiloxanes) and Silica Nanoparticles

Foaming of oils often confronts researchers in food, cosmetics, and petrochemical industries. Destabilization or stabilization of nonaqueous foams is fundamentally crucial for process control and product quality. Antifoams can be a useful method to control excessive foams. Nonetheless, the foaming mechanisms and the selection criteria of the most common antifoam, poly(dimethylsiloxane) (PDMS) oils, are not thoroughly discussed. The study of inorganic colloidal particles as foam stabilizers has drawn particular attention over the past years practically and academically, yet only a small part of literature focuses on nonaqueous foams. For these reasons, we have studied the effects of PDMS oils and silica nanoparticles on the foaming of oils. We find that the performance of silicone oils as crude oil antifoams is firmly related to PDMS viscosity and crude oil composition presumably because the solubilization of PDMS oils in hydrocarbons reduces with increasing viscosity of the polymers and the hydrocarbons. The findings also illustrate that nanoparticle hydrophobicity and concentration are the primary factors for the foam stabilization effect.