Colloidal Processing of Mg(OH) sub(2) Aqueous Suspensions Using Sodium Polyacrylate as Dispersant

The rheological behavior and stability of Mg(OH) sub(2) suspensions were studied in the presence of sodium polyacrylate with different molecular weights under conditions of different ionic strength and counterion valence (K super(+) and Mg super(2+)). Rheological properties, optical absorbance, and zeta potential measurements were conducted on the Mg(OH) sub(2) particle suspensions to assess the dispersing ability of the sodium polyacrylate dispersants. Adsorption isotherm measurements were applied to investigate the effect of counterions on the adsorption behavior. The results demonstrate that Mg super(2+) ions destabilize the Mg(OH) sub(2) suspensions more dramatically than K super(+) ions due to the stronger screening effect and special complexation of Mg super(2+) ions and carboxyl groups. The effect of molecular weights of NaPA on the rheological properties becomes more pronounced at higher solid loading because the NaPA with a molecular weight of 15,000 g/mol increases the viscosity more obviously than NaPA with a molecular weight of 1200 g/mol. The calculation results of interparticle interaction by the Hamaker 2 program show that the suspensions can achieve good stability with sufficient NaPA dosage, which coincides with the optical absorbance measurement results.