Study on dispersion stability of natural brucite in aqueous media

Abstract

A brucite suspension can absorb sulfur dioxide (SO2). It thereby plays a significant role flue gas desulfurization. However, the dispersion of a natural brucite suspension is low which seriously affects its efficiency for SO2 absorption. The dispersion stability and particle size of the brucite suspension are therefore, particularly important to investigate. The effects of types and dosages of inorganic dispersants on the particle size and dispersion stability of the brucite suspension have been investigated in the present study by performing sedimentation experiments and zeta potential tests. The results showed that the addition of 0.5 wt.% sodium hexametaphosphate (SHMP) had a positive effect on the dispersion stability of brucite in an aqueous medium. The effect of SHMP on the surface properties of the brucite particles was also studied by performing characterizations like scanning electron microscopy (SEM) and infrared spectroscopy (IR), and by using an extended DLVO theory (named after Boris Derjaguin and Lev Landau, Evert Verwey and Theodoor Overbeek). The results showed that SHMP was chemisorbed on the brucite particle surface. It also formed complexes with magnesium ions, and changed the zeta potential of brucite. In addition, calculations based on the extended DLVO theory showed that the sum of the steric hindrance-induced interaction energy, Van-der-Waals energy, and electrostatic energy changed from an unfavorable value to a favorable value with an increase in the particle distance. These results showed that the addition of SHMP could improve the desulphurization effect of the brucite suspension.