Influence of pH and Time on the Stability of Aqueous Alumina Suspensions Containing Sodium Polyacrylates: A Revisited Process

Abstract

The action of polyacrilates as stabilizing agents in alumina aqueous suspensions has been investigated using viscometry, zeta potential, and photon correlation spectroscopy (PCS) measurements. The present work emphasizes that the study of stability of dispersions using polyelectrolytes must necessarily include several techniques in order to evaluate different physicochemical properties of colloidal suspensions, and thus attain a wide comprehension of the system under analysis. In our point of view, this is necessary because, for instance, while viscosity measurements suggest that there is no advantage in the use of the polyelectrolyte at some pH values, particle size measurement as a function of time shows that the presence of PANa at that pH values allows a longer handling time in suspension processing. Low molecular sodium polyacrylate presented a good performance as a deflocculating agent, because it leads to dispersions of low viscosity, stable at a wide range of pH, and also low variation in particle size as a function of time.

The rheological behavior and stability of Mg(OH)2 aqueous suspensions in the presence of sodium polyacrylate

“…In the absence of KNO 3 , the sedimentation height decreases as the NaPA dosage is increased, leading to a more and more dense particle packing gradually. This means that the suspensions become more and more stable [25].…”

“…NaPA is the sodium salt of polyacrylic acid consisting of repeating units with -COO -Na + groups [18]. Since NaPA containing carboxylic acid groups is classified into a weak polyelectrolytes, the dissociation degree mainly depends on the solvent conditions, such as pH value and ionic strength [11,25,30]. Thus it will change the polyacrylates adsorption conditions of the particle surfaces leading to variations in the colloid stability and A c c e p t e d M a n u s c r i p t rheological behavior of concentrated suspensions [31].…”

“…Sodium polyacrylate (NaPA) with low molecular weight is one of the most frequently applied polyelectrolytes as a dispersant to induce stability by electrosteric stabilization [15,25]. Although NaPA has already been utilized in the preparation of stable Mg(OH) 2 suspensions effectively [26,27], there has never been a paradigm proposed to explain the contributing mechanisms of detectable experimental factors on the stability and rheological behavior of Mg(OH) 2 suspensions in the presence of NaPA.…”

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

“…The effects of NaPAA–PEO dosage and counterions (K + , Mg 2+ and Ca 2+ ) on the stabilization of suspensions were investigated by the sedimentation measurements. The sedimentation height of suspensions after 7 d is illustrated in Figure , indicating that the sedimentation height decreases with an increase in the NaPAA–PEO dosage, regardless of the counterions valence, leading to higher particle packing density . When the NaPAA–PEO dosage increases to 1.2 and 1.5 wt %, the suspensions are more stable with cloudy supernatant and low sedimentation height (seen in Figures S3–S6 in the SI).…”

Influence of pH on the Stability of Alumina and Silica Nanosuspension Produced by Wet Grinding

“…The adsorption of polymeric stabilizer like polyethylene oxide, polyvinyl alcohol, polyvinyl pyrrolidone and polyacrylic acid on colloidal silica and the stability of the aqueous suspension were widely reported in the literature (Wind and Killmann, 1998;So et al, 2001;Goncharuk et al, 2001;Wisniewska, 2010). Such reports were also found in the literature for alumina particles (Yokosawa et al, 2002;Shin et al, 2006). Preparation of nanoparticles by stirred media milling is very promising technique.…”