Synergistic effect of like and opposite charged nanoparticle and surfactant on foam stability and mobility in the absence and presence of hydrocarbon: A comparative study

Abstract

The aim of this study is to compare the synergistic impact of like and opposite-charged nanoparticle and surfactant systems on enhancing stability and mobility of foam in the absence and presence of oil which is not sufficiently discussed in the available literature. Stability of nanoparticle dispersion is examined at various levels of pH when nanoparticle and surfactant are in like and opposite-charged conditions. In situ modification of silica nanoparticle by opposite-charged surfactant is analyzed. Static stability tests as well as Hele–Shaw cell are employed to understand how nanoparticle and surfactant charges may control the stability and mobility of foam when oil is present/absent. The results indicate that surface properties of negative-charged silica nanoparticle can be modified by positive-charged surfactant. However, no modification is made on nanoparticle by surfactant carrying the same charge. Although, the mixture of like-charged nanoparticle and surfactant gives a slightly better static stability than the other one in both presence and absence of oil, both foams are not adequately able to resist oil destroying effects. When oil is absent, mobility of foam stabilized by like-charged particle and surfactant is lower. Addition of nanoparticle to the solution of same-charged surfactant increases foam apparent viscosity steadily, whereas in the case of opposite-charged surfactant solution, apparent viscosity increases at first, and then decreases by nanoparticle concentration. In the presence of oil, less mobile foam is generated by mixture of opposite-charged nanoparticle and surfactant, in contrast to the case which oil is absent. In situ modified nanoparticle stabilized foam also flows with an acceptable level of apparent viscosity when foam is detrimentally affected by oil. Model of foam flow in fracture revealed that in situ surface modified nanoparticle considerably affects the resistance of foam bubbles against deformation whereas it has negligible impact on foam film liquid term in apparent viscosity. Results of this study help to better understand in what extend the synergistic effect of nanoparticle on enhancing foam stability/mobility is controlled by combination of nanoparticle and surfactant surface charges.