LAUSR

Abstract The combined effect of surfactant and nanoparticles on the surface and interfacial tension is of great importance in various industrial processes. This study provides an insight into the combined effect of a non-ionic surfactant (Triton X-100 and Tween20) and SiO2 nanoparticles at the air–water interface using experimental and theoretical approaches. The surfactant concentration was kept constant at CMC, and nanoparticle concentration was varied from 0 wt% to 1.2 wt%. The results show that nanoparticles reduce the efficiency of Triton X-100 and Tween 20 surfactants at the air–water interface, mainly due to the adsorption of surfactants on NPs, which is also supported by the theoretical model. Furthermore, density functional theory simulations are conducted to understand the adsorption of the non-ionic surfactant on silica NPs with the variation in the degree of ionization of silica NPs. We have observed that the adsorption of the non-ionic surfactants on silica NPs reduces as the degree of ionization of NPs increases, which is in agreement with the experimental observations.