Cationic starch: an effective flocculating agent

A series of cationic starches (Cat St) have been developed by incorporating a cationic moiety N-(3-Chloro-2-hydroxypropyl) trimethyl ammonium chloride (CHPTAC) onto the backbone of starch in presence of NaOH. The cationic starches are characterized by elemental analysis, FTIR spectroscopy and intrinsic viscosity measurement. The flocculation characteristics of these starches have been evaluated in 0.25 wt% silica suspension by jar test. It has been found that among the four cationic starches, the one with longer CHPTAC chains shows the best performance. The flocculation characteristics of this starch are on silica suspensions compared with various commercially available flocculants.