Improvement in Salt-Tolerance of Aqueous Magnesium Hydroxide Suspensions by Comb-Like Polyelectrolyte

Abstract

The rheological behavior and stability of aqueous magnesium hydroxide (Mg(OH) 2 ) suspensions were studied in the presence of comb-like polyelectrolyte, namely, sodium salts of poly(acrylic acid)-poly(ethylene oxide) (NaPAA-PEO) at high ionic strength. Rheological, sedimentation and zeta potential measurements were conducted on Mg(OH) 2 suspensions to assess the dispersing ability of NaPAA-PEO.The adsorption behavior of NaPAA-PEO on the surfaces of Mg(OH) 2 particles was investigated by the adsorption isotherm measurements. The interparticle interactions were calculated by using the Hamaker 2 program to evaluate the effect of NaPAA-PEO dosage on the stability of suspensions. The results indicated that NaPAA-PEO, which is insensitive to ionic strength variation, could improve the salt-tolerance of Mg(OH) 2 suspensions and provide effective electrosteric stabilization, thus facilitating the production process and application of Mg(OH) 2 suspensions over broad range of ionic strength.

Effect of different parameters on caustic magnesia hydration and magnesium hydroxide rheology: a review

“…When it exceeded 50 wt.%, there was a remarkable shear-thinning behavior indicating the presence of particle packing in suspensions. As shown in figure 14, as the shear increased, the flocs were gradually destroyed and higher particle packing density was obtained with an increase in the shear rate [46].…”

“…The suspensions with NaPAA-PEO also exhibited excellent salt-tolerance for monovalent K + and divalent Ca 2+ and Mg 2+ ions [46].…”

Polyethyleneimine–Oleic Acid Complex as a Polymeric Dispersant for Si3N4 and Si3N4-Based Multicomponent Nonaqueous Slurries

“…Addition of polymeric dispersants is one of the main routes of controlling the stability of fine particles in liquid media. It is well-known that the structure of functional groups and chains in polymers must be carefully selected for effective adsorption on particles and generation of repulsive forces, respectively, based on the combination of different types of fine particles and solvents, to achieve improved stability of slurries. − Furthermore, the MWs of dispersants also need to be carefully considered based on particle sizes and/or their mean interparticle distances to generate effective steric repulsive forces without forming bridgelike networks of polymers when particles approach each other in slurries. ,, Therefore, many polymeric dispersants with different molecular weights and structures, such as polyacrylates, , polyacrylate-based block copolymers, − polyethylene-glycol-grafted comb-type polymers, − polyethyleneimine, , functionalized polyethyleneimine, , and other tailor-made substances have been synthesized based on polymer chemistry, leading to improved dispersion systems.…”