Preparation, structural characterization, and flocculation ability of amphoteric cellulose

A series of amphoteric celluloses (QACMCs) were prepared from sodium carboxymethyl cellulose (CMC) and 2,3-epoxypropyltrimethylammonium chloride (EPTMAC) with a cationic degree of substitution (DScat) of 0.24-1.06 and a carboxymethyl degree of substitution (DSani) of 0.60. The structures of the samples were characterized by FTIR and NMR spectroscopy, which revealed that DScat depended on the ratio of EPTMAC to CMC in the reaction mixture and that the substituent distribution of the cationic group at the C2, C3, and C6 positions of the QACMCs ranked as follows: C2 > C6 > C3. The QACMCs dissolved over a wide range of pH levels and exhibited flocculation ability against kaolin suspensions. In particular, the samples with high DScat exhibited excellent flocculation performance. In addition, the flocculation characteristics of the QACMCs depended on the pH of the kaolin suspension.