Interactions Between Surfactants And Particles In Multiphase Foam Systems

Foams are widely used in various fields,ranging from daily chemicals,firefighting to mineral flotation and oil recovery.However,foams are unstable thermodynamically,which is also a main reason to restrict its applications.The previous studies have shown that the addition of polymer particles and proteins can effectively improve the stability of the foam system.In this thesis,we have studied different foam systems formed by SiO₂nanoparticles and cosurfactants.We have maken a kind of ultra-stable foam system by optimizing the formulations.In the foams system,nonionic surfactant biological Alkyl Polyglycoside was adopted as the main foaming agents,while trace amounts of cationic surfactant C₁₂C₃C₁₂Br₂ was used to tune the surface of hydrophilic SiO₂nanoparticles into suitable wettability by adsorption.Spectroscopic ellipsometry,contact angle analysis,laser nanoparticle size analyzer,surface tension meter and interface rheometer were used to study the interaction between surfactants and particles in the multiphase solution.It was found that the hydrophobicity of particle surface increased after the adsorption of surfactant.Particles with suitable surface wettability can adsorbe onto the interface of foam film,and thus increase the mechanical strength of the film and delay the draining and disproportionation of film.Core plugging experiments showed that the ultra-stable multiphase foam system had a much better plugging effect than foams without particles.This kind of stable foam has potential applications in oilfields.The effects of salt ions,temperature,pH value on foam stability have also been studied.The results showed that small amount of salt ions can increase the foam volume to a certain degree,but with the salt concentration increase foam drainage half-life time decreased.It was implied that the multiphase foam system can tolerate salt ions to a certain degree.At pH 4,the foam was stable.If the pH was adjusted,the foam drainage half-life time would decrease significantly.When raising the temperature to above 45^oC,both foam volume and foam stability decreased significantly.It is indicated the multiphase foam system is sensitive to pH and temperature.We also studied the foam systems with formulations of different surfactants and particles.It was found that APG/SDS/SiO₂?N20D?did not form stable foam system,while APG/CTAB/SiO₂?N20D?formed a super stable foam system.Although APG/SiO₂?H15?system showed excellent foaming,its drainage half-life was only 40min,which was far shorter than foam systems of APG/C₁₂C₃C₁₂Br₂/SiO₂?N20D?or APG/C TAB/SiO₂?N20D?.Where N20D is hydrophilic SiO₂ nanoparticle,H15 is semi-hydrophobic nanoparticle.