Flocculation properties of high-substituted cationic starches

The flocculation behavior of high substituted (DS from 0.21 to 0.57) cationic polysaccharides prepared from hydrolyzed, hydroxyethylated or native potato starch was examined in the destabilization of kaolin dispersion. The influence of DS, molecular weight, accessibility of quaternary ammonium groups and dispersity of the cationic starches in water on the sedimentation rate of disperse phase was investigated. The different flocculation behavior of soluble or dispersible in cold water cationic starches was observed. The dispersible in cold water cationic starches obtained from potato starch under conditions of heterogeneous reactions, preserving the granules of the starch unchanged, exhibit a higher flocculation efficiency compared with the soluble cationic starches. Differences in mechanisms of flocculation by water-soluble and water-dispersible cationic starches are discussed.