Flocculation Studied with the ESA Technique

Walldal, Charlotte

doi:10.1006/jcis.1999.6119

Cited by 4 publications

(1 citation statement)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The mobility was measured on the 1 wt % solid/liquid dispersions. It has been shown that it is possible to achieve information about the particle charge by measuring the dynamic mobility of particles even in the presence of excess polyelectrolyte and for increased particle sizes (porous flocs), which are due to the flocculation by polyelectrolytes. , The mobility values were corrected for the electrolyte signal according to the method described by Desai et al Because of the occasionally large corrections made for the electrolyte signal, the accuracy of the mobility values was approximately ±0.05 × 10 -8 m 2 (V s) -1 .…”

Section: Methodsmentioning

confidence: 99%

Flocculation of Semidilute Calcite Dispersions Induced by Anionic Sodium Polyacrylate−Cationic Starch Complexes

2003

View full text Add to dashboard Cite

Polyelectrolyte complexes (PECs) formed by mixing oppositely charged polyelectrolytes are widely used as flocculation agents of aqueous solid/liquid dispersions. The complexes have been found superior to single polyelectrolytes in showing a substantially wider optimum concentration range for flocculation. In this work the flocculation performance and mechanisms induced by premixed complexes of cationic starch and anionic sodium polyacrylate (NaPA) on semidilute calcite dispersions were investigated by measuring the particle size and the dynamic mobility. The flocculation performance was studied as a function of the ratio of NaPA to starch, and the total amount of polyelectrolyte added. The influence of pretreatment of the calcite dispersions on the complex-induced flocculation was also investigated. The investigation clearly shows that, by using appropriate amounts of premixed NaPA and starch, the flocculation of the calcite dispersions was strongly enhanced compared to the case of using single NaPA or starch, respectively. Several mechanisms are involved in the enhanced flocculation induced by the two oppositely charged polyelectrolytes. These mechanisms are strongly dependent on the ratio of NaPA to starch, and the total amount of polyelectrolytes added. However, interparticle bridging by the polyelectrolyte complexes, and charge neutralization, induced by the deposition of the complexes, were found as the main reasons for the enhanced flocculation. Pretreating the bare calcite with anionic sodium polyacrylate changed the charge characteristics of the calcite from cationic to anionic. Despite the change in charge characteristics, the pretreatment did not drastically change the flocculation behavior of the semidilute calcite dispersions induced by the subsequent addition of premixed polyelectrolyte complexes. However, the pretreatment resulted in a slight shift in the ratio of NaPA to starch required for optimum flocculation.

show abstract

Section: Methodsmentioning

confidence: 99%