Sedimentation and stabilization of nano-fluids with dispersant

Stability of nanofluids is one of the major parameters which measures its effectiveness. The agglomeration of nanoparticles reduces the stability of nanofluids and consequently affects their technologically relevant properties. In this study, stability of alumina nanoparticles (size similar to 50 nm) in ethanol-water mixture with and without dispersant has been investigated. Sodium salt of poly methacrylic acid (SPMAA) as a dispersant were used in this investigation. Clear solution height with respect to time, sedimentary photographs and zeta potential techniques have been used to analyze the stability behavior of nano-fluid. The effect of binary mixture proportions and dispersion's pH has been investigated and discussed. The results showed that sedimentation, zeta potential and photographic techniques have a great correspondence with each other. SPMAA has been used as the dispersant in low concentration (0.03 ml) and has a negative impact on the stability of nano-fluids. The isoelectric point of alumina found to be at pH 7 but with dispersant shifted towards acidic region (pH 4.5). Higher binary mixture concentrations (10% and 90%) by weight exhibited good stability.