Effect of Inorganic Salt on Foam Properties of Nanoparticle and Surfactant Systems

Abstract

Abstract We have studied the effect of NaCl and CaCl2 on phase behavior of foaming aqueous dispersions containing mixtures of silica nanoparticles (Ludox CL) and sulfobetaine (LHSB). At the evaluated ratio, the phase behavior results show that at a low CaCl2 concentration, sedimentation occurs, whereas a stable aqueous dispersion could be achieved when the CaCl2 concentration reaches to 20%. The adsorption experiments show that high concentrations of both NaCl and CaCl2 reduce the adsorption of LHSB to CL. In the CaCl2 dispersion the adsorption decreases significantly and only a few LHSB molecules can be adsorbed on the CL surface. Therefore, without the lower hydrophobicity of LHSB adsorption less CL could adsorbed at the air/water interface. The results on gas permeability show that aqueous dispersions containing mixtures of CL and LHSB show no obvious difference to aqueous systems containing only LHSB. The surface dilatation module of the LHSB and CL system in CaCl2 solution also shows a similar variation to the system with LHSB alone, which is significantly different from the system with 20% NaCl. Finally, foam flow tests in a porous medium show that compared to a 20% CaCl2 dispersion with the LHSB and CL system in 20% NaCl, a finer foam and a higher pressure difference could be achieved.